Just Released! New Lower Prices!

July 13, 2006

Can antibiotics affect birth control pills?

Filed under: Uncategorized — Ashlynn @ 9:44 am

Birth control pills can be affected by certain antibiotics, making the Pill less effective and increasing your chances of pregnancy. Mid-cycle bleeding (spotting) may be the first sign that an antibiotic is interacting with the effectiveness of your birth control pills.

Antibiotics that have been shown to interact with birth control pills include:

  • rifampin (brand name Rifadin)
  • penicillin (Veetids)
  • amoxicillin (Amoxil)
  • ampicillin (Omnipen)
  • cotrimoxazole (Septra or Bactrim)
  • tetracycline (Sumycin)
  • minocycline (Minocin)
  • metronidazole (Flagyl)
  • nitrofurantoin (Macrobid or Macrodantin)

If you are using birth control pills and need to take an antibiotic, doctors generally recommend the use of a condom or spermicide as a back-up during and for a least one week after to help avoid your chances of pregnancy while taking the antibiotic. It’s recommended to follow this routine – use the pill, back-up method, and antibiotics together – as opposed to stopping the pill while taking antibiotics and restarting the following month. When you stop and restart it can cause unnecessary readjustment for your body.

While the “how” and “why” of antibiotics interfering with birth control pills is still unclear, with interferences only happening a few times, don’t take any chances. Always use a back-up method.

BirthControlBuzz is a service company that provides birth control prices, birth control types (prescription required), health administrative services, and birth control statistics predominantly to US patients seeking to purchase pharmaceuticals on-line.

For more information, call 1-866-868-8850 or visit http://www.birthcontrolbuzz.com/.

Birth Control Buzz is a service company that provides birth control prices, types of birth control(prescription required), health administrative services, and birth control statistics predominantly to US patients seeking to purchase pharmaceuticals on-line. For more information, call 1-866-868-8850 or visit http://www.birthcontrolbuzz.com/.

100 Comments »

  1. I know that antibiotics can affect birth control pills, but what about Mirena? I have been using it for 3 years with no problems, but after taking antibiotics about 6 weeks ago, I am having pregnanacy symptoms. Any information?

    Comment by Anonymous — October 29, 2007 @ 2:33 pm

  2. What information I could find showed that antibiotics do not affect Mirena..But having said that you should still take a pregnancy test to be on the save side. Here’s a link for further information (it’s a bit scientific). Note points #5 and #6.http://www.guideline.gov/summary/summary.aspx?ss=15&doc;_id=7286&nbr;=4339Hopefully this helps.p.s. “levonorgestrel-releasing intrauterine system” refers to the IUD

    Comment by Ashlynn — October 31, 2007 @ 8:18 am

  3. I have a question about birth control. In the 90′s, I did birth control for about 5 years and it took me over a year to get pregnant with my second child. I also took antibiotics several times during those years. Now my sister in law said, she got pregnant before she got married because of an antibiotic this also happen in the 90′s. I was under the understanding that back then the pill were so strong that it took a while for it to wear out. What are the adds here?

    Comment by golddigger — March 10, 2008 @ 7:28 am

  4. I just spoke with a nurse with Planned Parenthood, with the same question. She stated that there are no drug interactions with Mirena because it only secretes progesterone, not estrogen. However,you should check that your strings are in place monthly to ensure that your device hasn’t been dislodged, and take a pregnancy test to be on the safe side. No birth control method is 100% effective, except abstinence.

    Comment by Anonymous — November 13, 2008 @ 10:45 am

  5. I have been on Tri-Cyclen for nearly 3 years now, it has cleared up bad period pains and my acne. However, over the past few months my acne is becoming much more severe and I want to talk to my Dr. about trying Tetracycline to clear it up but am afraid this will make my birth control pills less effective. Should I be trying a stronger pill to clear my acne or will I be ok to try other medication?

    Comment by Anonymous — September 12, 2009 @ 10:39 am

  6. Dear Anonymous,Tetracycline will effect your birth control. It is one of the antibiotics listed on one of our similar blog posts about which antibiotics will effect birth control. Check out the post here: http://www.birthcontrolbuzz.com/blog/2007/05/what-antibiotics-affect-birth-control.htmlWhat I would suggest is that you speak to your Doctor about finding a birth control that will help with acne. Speak to your doctor about Diane. Diane is a birth control usually prescribed to treat acne.Goodluck :)

    Comment by Janine — September 14, 2009 @ 9:36 am

  7. uh.. good thread..

    Comment by Anonymous — December 12, 2009 @ 4:34 pm

  8. Hi i am on macrodantin for 2weeks and taking the pill microlite, will it affect the pill???

    Comment by Nicola — October 3, 2011 @ 4:30 pm

  9. Hi Nicola,

    I couldn’t find the pill microlite. Do you know if it has another name or if it was misspelled?

    Comment by Janine — October 4, 2011 @ 11:46 am

  10. I can understand why antibiotics would affect “the pill” and not the mirena. Is read on a website that it prevents the pill from absorbing correctly but what if you had to insert antibiotics vaginally bc of a yeast infection all while having the mirena? Would that affect it? I’ve been having pregnancy symptoms like sore breast, tightness in lower abnomin, and my appetite has increased tremendously! My daughter is one now, so I’ve had the mirena for almost a year. Any answers would be helpful! I plan on testing and talking to my doctor but until my appointment I need some answers :)

    Comment by nicole — December 5, 2011 @ 1:23 am

  11. Dear Nicole,

    There are some that you can take vaginally for localized infection (e.g. Metronidazole Gel for bacterial vaginosis)

    There are two ways antibiotics can have an effect on the pill (simple explanations) –

    1. As suggested, by decreasing absorption
    2. By increasing the breakdown and elimination of the pills through the liver (certain antibiotics)

    Mirena works by two mechanisms. First, the mechanical presence of the IUD. Antibiotics wouldn’t impact that factor. Second, the synthetic progesterone which keeps the lining of your uterus very thin add extra contraceptive protection. Unlike birth control pills/patches/rings the synthetic progesterone is in direct contact with its target tissue so even vaginal antibiotics are unlikely to affect hormone levels.

    Comment by Janine — December 5, 2011 @ 12:07 pm

  12. I get all of that I just didn’t know if there ways any ways that would be affected maybe too strong of meds but I did test negative. Im still confused bc now I have discharge from my nipples which to me looks like breast milk. I only got to nurse my daughter for 6 weeks and I dried up nicely so idk what could be going on. They have been very sore like when I was pregnant. I just feel pregnant, don’t really want to be. I wouldn’t mind if I was, I had trouble getting pregnant bc of PCOS so im blessed to have my little girl. I just want to know why I feel like this. If its bc of the mirena I don’t think ill keep it in much longer.

    Comment by nicole — December 6, 2011 @ 10:09 pm

  13. Dear Nicole,

    How did you feel with the Mirena before you had to take antibiotics? If everything was fine, what you are experiencing is probably not from the Mirena. I would suggest you wait until you are done taking antibiotics and see if the symptoms continue.

    Comment by Janine — December 7, 2011 @ 11:04 am

  14. Hi,
    Very helpful article!
    Last week, I was on Itraconazole for 2 days, then on Acyclovir for another 2 days while on birth control pills. I was also sexually active during this period.

    Is there any chance for pregnancy?

    Thanks in advance.

    Comment by Daisy — December 21, 2011 @ 8:44 am

  15. Dear Daisy,

    If you had unprotected sex during the period you are on an antibiotic that interferes with your birth control, your risk for pregnancy increases. To find out if you are pregnant, you can wait for your next period to come. If you don’t get your period, you can take a pregnancy test. If you do get your period then you should be fine.

    Comment by Janine — December 21, 2011 @ 9:55 am

  16. i was on antibiotics for five days and iam on yasmin for only 3months,had sex with a condom after the 5days, did not have my periods yet can i maybe be pregnant becuase my breast are swellen?

    Comment by luzeen — April 12, 2012 @ 8:45 am

  17. Dear Iuzeen,

    To find out if you are pregnant or not, take a pregnancy test 3 weeks after you had had sex with a condom 5 days after you stopped the antibiotics. If the pregnancy test says negative, you should be fine. The breast tenderness could just be from the pill. If the test is positive, then make an appointment with your doctor to get a more accurate test done.

    Comment by Janine — April 12, 2012 @ 12:27 pm

  18. I was prescribed septra ds for an uti and I’m currently on ortho tricyclin lo. My doctor said it would not affect my birth control but Im worried now because I had sex after the first day of taking the antibiotics. Will septra D’s interfere with my birth control?

    Comment by Elizabeth — June 7, 2012 @ 1:50 pm

  19. Dear Elizabeth,

    Septra does interact with Ortho Tri Cyclen Lo. I would advise you to use back up contraception (ie. condoms, spermicide) during the time you are on Septra up until a week after you stopped taking the antibiotic, just to be safe. If it has been within 72 hours of unprotected sex, you can use Plan B.

    Comment by Janine — June 8, 2012 @ 2:10 am

  20. I have been on Lybrel for two years, sexually active for 3 months. I had sex last night. I was prescribed metronidonzale cream to take once daily for 5-7 days. I didn’t tell my gyno I had sex the night before- should I wait to start using the cream? To avoid any chance of pregnancy (sperm living and the antiobiotic stopping my birth control today etc). When can I stop using a back up method after I finish treatment (ie the Lybrel becomes effective again).

    Comment by Kaitlin — June 27, 2012 @ 5:23 am

  21. Dear Kaitlin,

    I would advise you to start taking metronidazole cream 7 days after you had unprotected sex. While you are on metronidazole, make sure you use back up contraception (ie. condoms or spermicide) up to a week after you have stopped using the antibiotic just to be on the safe side.

    Comment by Janine — June 28, 2012 @ 2:06 am

  22. I was taking zpack while on my period and had unprotected sex? Could there be a chance of pregnancy?

    Comment by Elizabeth — June 29, 2012 @ 9:21 am

  23. Dear Elizabeth,

    Zithromax does interfere with your birth control, so there could be a chance you could have gotten pregnant. Wait for your period, if it is late, take a pregnancy test. If you do get your period, then you should be fine.

    Comment by Janine — July 3, 2012 @ 3:36 am

  24. Hi, I am taking beyaz and just got prescribed SMZ/TMP DS TAB 800-160 for a UTI. This is the generic for Septra which is on this list. Do I need to use other contraceptives during this time? and for how long after if so?

    Comment by Jackie — July 6, 2012 @ 10:29 am

  25. Dear Jackie,

    You do need to use back up contraception (ie. condoms or spermicide) when on SMZ/TMP DS TAB 800-160. Please use back up contraception during the time you are on the antibiotic up to a week after you have stopped taking the antibiotic.

    Comment by Janine — July 9, 2012 @ 2:23 am

  26. Hi, i am on birth control patch and had unsafe sex 2 days ago. Today i’ve been told to take Metronidazole. If i start taking it now will there be a chance that i can get pregnant, because i know sperms can last few days in the body. thanks!

    Comment by sid — July 13, 2012 @ 8:50 am

  27. Dear sid,

    If you are on the patch, you should be protected from pregnancy. Metronidazole does not decrease the effectiveness of your birth control patch. You should still be protected from pregnancy if you stay on the patch and take metronidazole.

    Comment by Janine — July 16, 2012 @ 1:08 am

  28. I was taking birth control for about two weeks and I got on antibiotics and I stopped taking my birth control because I had missed a few days of it. I have had unprotected sex a few times during this time period. I still haven’t started my period it’s been almost three weeks. Should I be worried? Or can that just make my period late?

    Comment by Tyler — July 24, 2012 @ 12:43 am

  29. Dear Tyler,

    Go get a pregnancy test. If it is positive, make an appointment with your doctor.

    Comment by Janine — July 24, 2012 @ 1:18 am

  30. I am on Tricylen Lo and have been on birth control for a year. I was on antibiotics for my wisdom teeth for one week. About 12 days after I stopped them I had unprotected sex with my boyfriend, but he pulled out. Should I be okay. Possibility of pregnancy?

    Comment by joanna — July 25, 2012 @ 12:51 am

  31. Dear joanna,

    It sounds like you should be okay because you had unprotected sex almost 2 weeks after you stopped taking your antibiotics. If you are worried you can take a pregnancy test if your period is late.

    Comment by Janine — July 25, 2012 @ 3:19 am

  32. Thanks for the reply Janine. What is the earliest you are able to have sex after antibiotics?

    Comment by joanna — July 25, 2012 @ 5:22 am

  33. I’m taking Loestrin FE 1.5/3028 and was also taking cephalexin 500mg for 1 pill for 7 days. Should i use back up protection? If so for how long after I quit taking cephalexin?

    Comment by tasha — July 25, 2012 @ 8:31 pm

  34. Hi Joanna,

    A week after you have stopped taking antibiotics, you should be able to have sex again :)

    Comment by Janine — July 26, 2012 @ 12:54 am

  35. Dear Tasha,

    You should be using back up contraception (ie. condoms or spermicide) because cephalexin reduces the effectiveness of your birth control pill. Use back up contraception up until a week after you have stopped taking the antibiotic.

    Comment by Janine — July 26, 2012 @ 1:02 am

  36. Hi, im a bit worried as am taking yasmin birth control pills but am now taking penicillin for tonsilitis…started taking them monday night and had unprotected sex last night (tues) what are my chances of pregnancy? How quickly do the antibiotics take affect? Many thanks.

    Comment by nikki — July 31, 2012 @ 3:33 pm

  37. Dear nikki,

    Antibiotics works right away. Since you started taking them on Monday and you had unprotected sex on Tuesday, I would advise you to take Plan B to make sure you did not get pregnant. While on penicillin, use back up contraception ie. condoms or spermicide up until a week after you have stopped taking penicillin.

    Comment by Janine — August 1, 2012 @ 1:49 am

  38. Hi I have been taking Solodyn (Minocycline HCI, extended release tablets for 10 days now to treat the folliculitis I have on my face. I have used Ortho TriCylen Lo for about a month, my dermatologist wants me to continue to use Monocycline (generic 100 MG) for another 30 days. How long do I have to wait until I can have unprotected sex?

    Comment by Teresa — August 20, 2012 @ 11:18 pm

  39. Dear Teresa,

    You have to wait until a week after you have stopped taking Minocycline HCl.

    Comment by Janine — August 21, 2012 @ 1:17 am

  40. Had unprotected sex on thursday and had mylast bcp same day, started taking antibotics on friday no bcp , started bleeding(not spotting) on monday , could I be having a bad reaction to the antibiotics or is it that I stopped taking my bcp

    Comment by letta — August 27, 2012 @ 2:04 pm

  41. Dear letta,

    You are bleeding because you have stopped the birth control pills.

    Comment by Janine — August 28, 2012 @ 1:04 am

  42. I am taking minocycline for acne and I have taken it so long I wasn’t even thinking when I had unprotected sex today spur of the moment..I haven’t had breakthrough bleeding in the last 5-6 months but I am still on the antibiotics..I have 6 day left in my birth control pack and I had sex today is there any chance I could be pregnant and will the morning after pill work tomorrow because the pharmacy is closed

    Comment by Jamie — September 3, 2012 @ 8:08 am

  43. Dear Jamie,

    Minocycline does affect birth control pills. If it has been within 48 hours since you had unprotected sex, you can still use plan B. If it is more than 48 hours, I would recommend you talk to your doctor about other emergency contraception methods to make sure you are not pregnant.

    Comment by Janine — September 4, 2012 @ 1:39 am

  44. I’ve been on mirena for about 3 months and before that i was on depo so haven’t had my period, i have one child about to be 2 and was on depo before her. I got prescribed antibiotics for a viral throat infection, i started feeling dizzy, and sick to my stomach and hot just randomly one day and it continued, I mean i felt like i was just ready to throw up at any time i ski felt very weak, is there a chance i could be pregnant and what is the best time to cheek or Waite before i take a test

    Comment by amber — September 12, 2012 @ 2:59 pm

  45. Dear amber,

    You can take a pregnancy test now to see if you are pregnant, but it sounds like what you are experiencing is from the antibiotics you are taking. How much longer do you need to take the antibiotics? Which antibiotic are you taking?

    Comment by Janine — September 13, 2012 @ 1:15 am

  46. Hello! So I just got prescribed macrodanin and i was wondering when the best time to get pregnant on birth control and antibiotics would be? I can start a fresh pack of birth control tomorrow when I start my antibiotics. I have pcos and have been ttc for 10 years and decided why not try this.

    Comment by Tami — October 8, 2012 @ 4:58 pm

  47. Dear Tami,

    If you are trying to get pregnant, you can just take Macrodantin without the birth control pills. Speak to your doctor about the best times to get pregnant in your situation.

    If you are not trying to get pregnant, do not take Macrodantin with your birth control pills. Macrodantin will reduce the effectiveness of your birth control pill. I would advise you to use back up contraception during the time you are on antibiotics up until a week after you have stopped taking Macrodantin.

    Comment by Janine — October 9, 2012 @ 2:09 am

  48. This post was very helpful. I was told to use a backup contraceptive while on flagyl but wasn’t told for how long. Thank you!

    Comment by Christine — November 1, 2012 @ 1:08 pm

  49. I had to take Cephalexin 500 mg 4 times a day for 7 days. I am on Ortho Novum 7/7/7 28. My last antibotic was the first 2 days of my 3rd week of bcp. The period came the 4th week. Now I am on my new pack of pills and 11 days off of antibotics. Do I need to use a backup birth control for this new pack?

    Comment by Julie — December 1, 2012 @ 10:59 pm

  50. I have been on Ortho Tri-Cyclen for almost 9 months. On November 25th i had strep throat and got a shot of penicillin. Then on December 1st, i had unprotected sex for five minutes then switched to a condom. Could i be pregnant?

    Comment by Ambur — December 12, 2012 @ 10:12 am

  51. Dear Ambur,

    It doesn’t sound like you could have gotten pregnant. Just in case you can take a pregnancy test to make sure you are not pregnant!

    Comment by Janine — December 13, 2012 @ 5:19 am

  52. I started my bc which is loestrin, the lowest dose 20 mcg on the 28th of November after my period. On the 6th I got the stomach flu and was prescribed penicillin and promethazine. I have had nausea and sore boobs for the past week now and my stomach is sore to the touch. I’ve been off of the penicillin for 3 days now and yes we have unprotected sex. What are my chance that I’m pregnant? My mother got pregnant with me while on birth control and taking penicillin which is why I’m so worried with my symptoms.

    Comment by ell — December 21, 2012 @ 12:17 pm

  53. Dear ell,

    Penicillin does reduce the effectiveness of your birth control pill. Chances of you becoming pregnant is very high. I would advise you to take a pregnancy test in a couple of weeks.

    Comment by Janine — December 24, 2012 @ 3:02 am

  54. Hello, last week I had took penicilin, I last took penicilin on friday 28th. And yesterday (5th jan) I had unprotected sex. Could I be pregnant?

    Comment by Erin — January 5, 2013 @ 6:48 am

  55. Dear Erin,

    I always advise girls to use back up contraception up until 1 week after they have stopped taking the antibiotics just to be sure. I would take a pregnancy test to find out if you are pregnant in a few weeks to see if you are pregnant.

    Comment by Janine — January 8, 2013 @ 2:45 am

  56. Hi I took one single pill of antibiotics earlier this wk for a tooth paim does that affect my birth control?

    Comment by priscilla — January 15, 2013 @ 2:00 am

  57. Dear Priscilla,

    It depends on which antibiotic you took. Do you know what the name of that antibiotic is?

    Comment by Janine — January 15, 2013 @ 4:58 am

  58. Hi i was on levlen ED for almost a year now and i took alprim for 7 days.. i am having brownish spotting 3 days before my actual period am i pregnant? Thankyou

    Comment by kj — January 31, 2013 @ 7:45 pm

  59. Dear kj,

    The spotting can be caused by Alprim. I would advise you to use back up contraception for the time being up until a week after you have stopped taking Alprim. To confirm you are not pregnant, you need to take a pregnancy test. Wait a couple of weeks before you go to your doctor’s office for a more accurate pregnancy test.

    Comment by Janine — February 1, 2013 @ 1:20 am

  60. hi im on mono tricylen lo birth control and am taking solodyn. Will that interfere?

    Comment by mack — February 1, 2013 @ 2:21 am

  61. Dear mack,

    Solodyn does reduce the effectiveness of Ortho Tri Cyclen Lo. Please use back up contraception while on Solodyn up until a week after you have stopped taking Solodyn.

    Comment by Janine — February 4, 2013 @ 2:31 am

  62. Hi,

    I’ve been on birth control for about 7 months. On January 4th I had my wisdom teeth removed and my doctor had prescribed me penicillin for about a week. I was taking them along with my birth control pills. I did not have unprotected sex during the time I was on penicillin but right after 2-3 days after finishing the penicillin, my period came and I had unprotected sex right after. Do you think I might be pregnant? Or is the chance very little? Thanks.

    Comment by Lynn — February 4, 2013 @ 12:46 pm

  63. Dear Lynn,

    Since you didn’t have sex until a week after you have stopped taking Penicillin, you should be fine.

    Comment by Janine — February 5, 2013 @ 5:14 am

  64. Hi,

    I been on camila for a year, however I been on metronidazol for a few days. I had uprotected sex the other night and I would like to know is there an chance of me getting pregnant?

    Comment by kn — February 5, 2013 @ 8:53 pm

  65. Dear kn,

    Metronidazole does reduce the effectiveness of Camila. I would advise you to use back up contraception while on Metronidazole. Depending on how long ago you last took Metronidazole, chances of you becoming pregnant may have increased.

    Comment by Janine — February 8, 2013 @ 2:00 am

  66. Hi, I am taking Azithromycin because I have strep. Will it effect my birthcontrol (loestrin24fe)?

    Comment by Charlotte — February 9, 2013 @ 2:31 pm

  67. I am on the birth control pill ortho cyclen. I had to get my wisdom teeth taken out the last week of December 2012, and they put me on antibiotics for a week before my surgery and for another two weeks after that, everytime I had sex I would always use condoms because the dr said it could make the pill ineffective. I had a regular peroid in January 2013 but now I started bleeding a week before my February period, could this still be an effect of.the antibiotics or what could this be

    Comment by Naomie — February 11, 2013 @ 2:09 am

  68. Dear Charlotte,

    Azithromycin does reduce the effectiveness of Loestrin 24 fe. I would advise you to use back up contraception while on Azithromycin up until a week after you have stopped taking Azithromycin to make sure you don’t get pregnant.

    Comment by Janine — February 12, 2013 @ 1:52 am

  69. Dar Naomie,

    I am glad to hear you have taken the right precautions while on antibiotics. Your period will be affected because the antibiotics did make your pill ineffective and that is why your period came early. Continue taking your pills as you normally would and your next period or the one after that should be on time.

    Comment by Janine — February 12, 2013 @ 1:56 am

  70. Okay so last Tuesday night I had unprotected sex and he busted inside me and the next morning at 10a.m I went to get my wisdom teeth out. I took the antibiotics (penicillin 250mg) an hour later after I was done and got home. So does that mean I could be pregnant? I am on birth control though but I know that the antibiotics decrease the affect of the birth control. I’m using beyaz.

    Comment by Desiree — February 18, 2013 @ 3:54 pm

  71. Dear Desiree,

    Penicillin does affect Beyaz. If you only took Penicillin once that day then you should be okay. As long as you are still taking Beyaz every day as you normally would.

    Comment by Janine — February 26, 2013 @ 6:42 am

  72. I am on Trinessa. I just started a new pack on Saturday. I also began taking metronidazole on Saturday. I asked my pharmacist if I needed to use a back up method and he told me no. Is this accurate? My husband and I have had unprotected sex twice since I began taking both medications.

    Comment by Jennifer — February 28, 2013 @ 10:16 am

  73. Dear Jennifer,

    Metronidazole does reduce the effectiveness of TriNessa. I would advise you to use back up contraception up until a week after you have stopped taking metronidazole. If your period is late, take a pregnancy test.

    Comment by Janine — March 1, 2013 @ 2:00 am

  74. It’s my first month on camila. I’m 1/2 way through my 3rd week on it. My gynecologist also prescribed a zpack (azithromycin) for a sinus infection, which I’ve been taking for four days. My husband and I had unprotected sex last night, should I be worried?

    Comment by Dana — March 5, 2013 @ 10:45 am

  75. Dear Dana,

    Azithromycin does reduce the effectiveness of Camila. I would advise you to first use back up contraception (ie. condoms or spermicide) up until a week after you have stopped taking zpack. Second, take a pregnancy test in a few weeks to see if you are pregnant. If the test came out negative then you should be fine. If it is positive, make an appointment with your doctor to get a more accurate pregnancy test done to confirm the pregnancy.

    Comment by Janine — March 7, 2013 @ 1:32 am

  76. Hi,

    I am 24 years old and I have been on ortho tricyclen lo for about 8 years now. I started taking amoxicillin (875mg twice a day) for 10 days. I am completely done with the antibiotic now. My husband and I had unprotected sex two or three times while I was on the antibiotic. (I always thought that it was a myth that they affected your pills!). My period is due to start this Wednesday and I am having very light bleeding just when I use the bathroom. It started yesterday. Do you think I might be pregnant? Or what are the chances? I have never had spotting during the 8 years I have been on ortho tricyclen lo. And my periods have always been regular.

    Thanks!

    Comment by Lily — March 23, 2013 @ 2:37 am

  77. Dear Lily,

    The spotting is definitely from antibiotics. Amoxiciliin does reduce the effectiveness of Ortho Tri Cyclen Lo. Since you had unprotected sex two or three times while on Amoxicillin, I would advise you to take a pregnancy test.

    Comment by Janine — March 27, 2013 @ 1:28 am

  78. I have been among birth control for the past 2 years FAITHFULLY. I was put on penicillin for a week recently. While taking my placebo pills I had unprotected sex. And my period started lightly later that day. However. It didnt fully come on the the following morning. Are there any chances of me being pregnant

    Comment by Patrice — March 30, 2013 @ 1:09 pm

  79. Dear Patrice,

    During the week you are on Penicillin, if you did not have unprotected sex you should be fine. Just to be on the safe side I would take a pregnancy test to confirm you did not get pregnant in a couple of weeks.

    Comment by Janine — April 1, 2013 @ 1:39 am

  80. Hi,I was on the mesigyna one mth shot and stop taking it on the 16 of January of this year.Last week I was taking klaracid antibiotic and this week doxocycline.I have unprotected sex how long before the mesigyna comes out my system I want to get pregnant

    Comment by Lacole — April 13, 2013 @ 11:06 pm

  81. I was prescribed amoxicillin while taking Apri for birth control. Six days after starting the antibiotic, I had sex. I used a condom, but it broke. Went the next morning to get the morning after pill just to be on the safer side. I haven’t had sex since that incident. I usually get my period on the 6th day of inactive pills in my pack. Today is day 7. I’ve been cramping lightly for two days with no bleeding.

    Comment by Natalie — April 14, 2013 @ 4:22 am

  82. Dear Lacole,

    If you are trying to get pregnant, it may take up to 3 months for your body to get back to it’s regular rhythm. I would advise you to speak to your doctor about preparing your body for pregnancy and he/she would be able to answer any questions you may have.

    Comment by Janine — April 15, 2013 @ 1:13 am

  83. Dear Natalie,

    How long ago was it when you took the morning after pill? Did you experience any bleeding when you were on amoxicillin?

    Comment by Janine — April 15, 2013 @ 1:17 am

  84. Hi,

    I have been taking birth control for 4 years now, and I have been dating my boyfriend for the past 8 months. Just last Friday I went to my doctor because I was experiencing pain during sex, some discharge and burning. It turned out I have Bacteria Vaginious. I have never even had a yeast infection or any other complication in my life, so I was quite shocked. My doctor put me on Metronidazole, for 7 days. I started on last Friday and take them to this Thursday. After only taking the pills for 2 days, i already feel back to normal and fine, but I of course will finished the prescription, to avoid it coming back.

    So here’s my question. My boyfriend and I had unprotected sex on Saturday and Sunday, and I am still taking my birth control everyday along with the medicine, but I am worried that I shouldn’t have done that, because I understand that taking antibiotics with birth control can increase risk, so should I be concerned and go to my pharmacy and get Plan B? And also if I do take Plan B, how long does it actually stay in your body for? I know you have to actually take it within 72 hours, but how long will it stay in my system for?

    Thanks so much, I am just desperate for an answer!!

    Comment by Jessica — April 15, 2013 @ 1:46 am

  85. Dear Jessica,

    Which birth control pill are you on? Metronidazole may have decreased the effectiveness of the birth control pill so I would advise you to take Plan B if it is not too late. Plan B would only stay in your body for 24 hours.

    Goodluck!

    Comment by Janine — April 16, 2013 @ 2:25 am

  86. I am taking Gianvi. Thank you for also answering me!

    Comment by Jessica — April 16, 2013 @ 10:55 am

  87. Hi there!

    I’ve been on Levora .15/30 for a couple years now. On the 13th of April, I was prescribed amoxicillin 875 mg tabs for an ear infection. I was to take them three times a day for ten days. From 13 April 18 April, I took thirteen tablets, due to missing doses and such. On 19 April, I had sex with my boyfriend. We used a condom with no spermicidal lube, but we are almost positive that a decent amount of sperm leaked out of the condom; we aren’t sure how much. When I came home that night, I freaked out and kind of accidentally took three birth control pills within twelve hours. We’ve been doing a lot of research on the Internet, and most of the evidence we’ve seen is conflicting. It has been a little under four days since our episode, and I’m not sure what to do. My next period won’t be for a month and a half, so I’m not sure how to go about this. I’ve heard Plan B, the Ella version, is acceptable, but not fully effective, up to five days after unprotected sex. We’re just worried, because neither of us are in a position to take care of a baby.

    Thanks!

    Comment by Emilee — April 22, 2013 @ 12:33 am

  88. Dear Emilee,

    Amoxicillin reduces the effectiveness of Levora so by taking 3 pills on April 19 will not help increase your chances of not getting pregnant. Since it is also too late to take Plan B (taking Plan B instead of the 3 Levora pills would have helped your chances because Plan B does not interact with Amoxicillin, so it would be a good idea to keep that handy in case this situation happens again), I would advise you take a pregnancy test in the next couple of weeks. There is a pregnancy test that can detect pregnancy as early as 3 weeks called First Response. You can also get an accurate pregnancy test done at your doctor’s office. If you are not pregnant, then you are fine. If you are pregnant, talk to your doctor about your options.

    Comment by Janine — April 22, 2013 @ 3:32 am

  89. Been on BC Trinessa for a couple years and a total of about 8 consecutive at this point. Was prescribed Azithromycin in late March (5 day pack). Last pill of 5 pack taken on the 27th of March. Husband and I had sex on the 13th of April(within last 5 days of cycle before period to arrive). Period was due the 16th of April. Previous period in March was light and period in April was very light. February period was normal and we had sex on the 25th of February(within 5 days of next cycle). Did not have plans to have a child but wondering what you think our odds are of being pregnant?

    Comment by Kathy — April 25, 2013 @ 11:00 am

  90. Dear Kathy,

    Since you didn’t have sex while on Azitrhomycin and up to two weeks after you have stopped taking Azithromycin, chances of you becoming pregnant during that time is very slim.

    Comment by Janine — May 2, 2013 @ 3:36 pm

  91. I was worried I might be pregnant because me and my boyfriend were in the shower. We didn’t have sex, but we did other things. So I took plan B, but I also continued to take minocycline. Do you think I can still become pregnant?

    Comment by Ann — July 24, 2013 @ 5:32 am

  92. Hello, I took Plan B before the 72 hours. 6 days after i started metrodinazole and fluconazole. Can I still get pregnant even if the antibiotic was taken a week later? Thank you

    Comment by Karla — August 12, 2013 @ 6:13 pm

  93. Dear Karla,

    Plan B does not interact with metrodinazole or fluconazole, but metrodinazole and/or fluconazole may interact with the birth control pill you are on. Let your doctor know you are on birth control pills when they are prescribing any medications to you so that they know to not prescribe you a medication that will interact with your birth control pill.

    Comment by Janine — August 20, 2013 @ 9:51 am

  94. Dear Ann,

    Plan B and minocycline does not interact with each other. You are safe!

    Comment by Janine — August 20, 2013 @ 4:09 pm

  95. Does macrodantin affect the mini pill cerazette?

    Comment by Jane — August 30, 2013 @ 3:34 am

  96. Hi,
    I just started on cephalexin GenRx taking one capsule four times a day. I use Levlen ED as birth control, will this ‘cephalexin’ antibiotic affect my birth control pill?

    Many thanks!

    Comment by Kirsty — September 16, 2013 @ 4:06 am

  97. Hi Kirsty,

    Cephalexin does reduce the effectiveness of your birth control. Make sure you use back up contraception (ie. condoms/spermicide) for up to a week after you have stopped taking cephalexin.

    Comment by Janine — September 16, 2013 @ 9:25 am

  98. Dear Jane,

    Macrodantin does decrease the effectiveness of Cerazette. Make sure you use back up contraception (ie. condoms/spermicide) for up to a week after you have stopped taking Macrodantin.

    Comment by Janine — September 16, 2013 @ 9:31 am

  99. Hi i just started taking the antibiotic nitrofurantoin mono 100mg substituted for macrobid 100mg. I am on the depo shot injection. My question is can you become pregnant with these two? I took the antibiotic yesterday at 12 pm had unprotected sex last night then took the antibiotic again at 12 am. Should i be worried about pregnancy?

    Comment by Tiffany — November 13, 2013 @ 12:21 pm

  100. Dear Tiffany,

    You should be okay. Nitrofurantoin does not reduce the effectiveness of Depo Provera.

    Comment by Janine — December 16, 2013 @ 2:57 pm

RSS feed for comments on this post. TrackBack URL

Leave a comment