Do Antibiotics Affect The Efficacy Of The Birth Control Pills?

Posted on Mon, 3 Oct 2016

Question: hi good afternoon, I'm 23 years old and I am taking birth control for over a month now. In the past 2 months I had to take plan b twice due to unprotected sex and that messed up my cycle. Yesterday I was super sick and I am taking an antibiotic called azithromycin 500 mg. I had unprotected sex thinking that the birth control will cover me from pregancy. I read online that antibiotics may make birth control not work. And I checked in my apps that I was fertile. so, pretty much I don't know what to do and I want someone to help me make my decision about buying the plan b or not. please I need help and I don't want to get pregnant. I know I was dumb for not using a condom but he did not wanted to use it. I need advice please. it has been almost 16 hours after unprotected sex. thank you

Answered by Dr. Purushottam Neurgaonkar (28 minutes later)

Brief Answer:
No effect with single dose of antibiotics. Please don't worry.

Detailed Answer:
Hi there, Dr. Purushottm Neurgaonkar welcomes you to HCM VIRTUAL CLINIC. I have gone through your question, and I think I have understood your concern. I will suggest you the best possible treatment options.

1 ) First of all do not panic.

2 ) If you are regularly taking the birth control pills regularly and as directed, then you are already protected against the pregnancy.

You need not worry about the pregnancy. Also , you need not take any emergency contraceptive pill.

3 ) Your concern about efficacy of birth control pills when you take antibiotics is true , but to a certain extent only.

4 ) Certain antibiotics when taken over a prolonged period of time, do cause some effects on the enzyme system of liver , and alter efficacy of birth control pills.

But there should be no issue with a single dose of antibiotic like Azithromycin.
So please do not panic and do not worry about the pregnancy.
Also, no need to take any add on emergency contraceptive pill.

I hope this answer helps you.
Please do rate this answer and write about the helpfulness of the answer. I will highly appreciate.
Thanks.
Dr. Purushottam Neurgaonkar.

Above answer was peer-reviewed by : Dr. Prasad

Follow up: Dr. Purushottam Neurgaonkar (35 minutes later)

yes I have been taking my birth control as indicated and at the same time. it is just that I also don't know where my cycle falls into. plan b has messed up my cycle that I don't even know when the next one is going to come. the azithromycin that I was taking is 500 mg for 3 days. I was on day #2 when I did it. I worry because it is a strong dose of antibiotics and I am really scared of getting pregnant. I also have an app that tells me when I'm going to be fertile and when is my next cycle going to come. I was supposed to be fertile yesterday. because the last day of my period was on last sunday... so I worry that the birth control might not make any effect and I was fertile, having a high risk of becoming pregnant. I don't like and want to take plan b, but if I have to I will. I try to relax, and think that everything will be fine but I still worry

Answered by Dr. Purushottam Neurgaonkar (10 minutes later)

Brief Answer:
3 days of Azithromycin will not alter efficacy of birth control pills.

Detailed Answer:
Hi there,
Thanks for appreciating the answer and reverting back.

As discussed earlier, the birth control pills if taken regularly, they already have started working towards supressing the egg formation. So even if you are on day of ovulation, it is going to protect you against the pregnancy.

As per medical text books of pharmacology are referred , it takes a long course of antibiotics to alter the efficacy of birth control pills.
Also, with 3 doses of Azithromycin, liver enzyme changes do not take place to hamper efficacy of the birth control pills.

So please do not worry about the pregnancy . Also, you need not take emergency contraceptive pill.

I hope this answer helps you.
Thanks.
Dr. Purushottam Neurgaonkar.

Above answer was peer-reviewed by : Dr. Prasad

Follow up: Dr. Purushottam Neurgaonkar (33 minutes later)

thank you for answering all my questions and to help me out with my problem. I really appreciate it. so, it should be fine if I take the third tablet of azithromycin today? And, last question. as a back up plan, what can I do if I get pregnant? I am a student almost finishing my career, I am not even married to my partner and not ready whatsoever to have a baby. what are my options? I know it sounds horrible, I kind of hate myself asking that type of question. but I just want to know. thank you so much for answering again. I do appreciate your feedback

Answered by Dr. Purushottam Neurgaonkar (7 hours later)

Brief Answer:
take Azithromycin, if needed pregnancy termination with pills possib

Detailed Answer:
Hi there,
Thanks for appreciating the answer and reverting back.

You can definitely take Azithromycin dose . Please do not worry at all.

For your information, please note that you can opt for termination of the pregnancy with medicines safely till 9 weeks of pregnancy under medical supervision.

You can simply opt for this , if you happen to get pregnant by any chance.

Please do take the birth control pills regularly as suggested.

I hope this answer helps you. Thanks.
Dr. Purushottam Neurgaonkar.

Note: Revert back with your gynae reports to get a clear medical analysis by our expert Gynecologic Oncologist. Click here.

Above answer was peer-reviewed by : Dr. Yogesh D