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/.
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
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
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
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
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
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
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
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
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
hi im on mono tricylen lo birth control and am taking solodyn. Will that interfere?
Comment by mack — February 1, 2013 @ 2:21 am
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
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
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
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
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
Hi, I am taking Azithromycin because I have strep. Will it effect my birthcontrol (loestrin24fe)?
Comment by Charlotte — February 9, 2013 @ 2:31 pm
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
I am taking Gianvi. Thank you for also answering me!
Comment by Jessica — April 16, 2013 @ 10:55 am
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
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
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
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
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
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
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
Dear Ann,
Plan B and minocycline does not interact with each other. You are safe!
Comment by Janine — August 20, 2013 @ 4:09 pm
Does macrodantin affect the mini pill cerazette?
Comment by Jane — August 30, 2013 @ 3:34 am
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
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
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
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
Dear Tiffany,
You should be okay. Nitrofurantoin does not reduce the effectiveness of Depo Provera.
Comment by Janine — December 16, 2013 @ 2:57 pm