8 Medications That Can Interfere with Your Birth Control Pills

The SMSNA periodically receives and publishes ‘guest editorials.’ The current article was submitted by Mia Barnes, a freelance writer and researcher who specializes in women's health, wellness, and healthy living. She is the Founder and Editor-in-Chief of Body+Mind Magazine.

Interactions happen when medicines, foods or herbal remedies change the way substances act in the body when taken at the same time. One drug may make the other less or more effective. For instance, some of the meds you’re taking may be messing with your birth control pills, which is troublesome if you’re not ready to get pregnant. Below are eight medications you should avoid or replace if you’re on contraceptives.

1. Antibiotics

Almost every medicine cabinet in American homes has a supply of penicillin and amoxicillin. Antibiotics treat many infections, from acne to complex pneumonia. While they’re generally safe to use, drug interactions may happen when you combine them with contraceptives.

One study found antibacterial drugs impair hormonal contraceptives. Unintended pregnancies were seven times more common in those taking antibiotics and 13 times more likely in people taking enzyme-inducing antibacterial drugs.

2. Anticonvulsants

Drugs that treat seizures can affect the metabolism of hormonal pills, reducing the efficacy of oral contraceptives. Medication management requires special attention for people living with epilepsy but who have an active sex life. Fortunately, only specific kinds have such an effect, and they are:

• Eslicarbazepine
• Carbamazepine
• Oxcarbazepine
• Phenobarbital
• Topiramate
• Perampanel
• Phenytoin
• Primidone

A workaround to the issue is asking your healthcare provider to change to another pill that doesn’t interact with your fertility control drugs.

3. GLP-1 Agonists

GLP-1 agonists are new medications that help promote weight loss and sugar regulation, featuring brands like Ozempic, Wegovy, and Mounjaro. Obesity has a prevalence rate of 41.9% in the U.S., so these drugs are likely to end up in the hands of millions. However, they can tamper with your birth control, reducing its effectiveness and making unintended pregnancy more likely.

The odds increase when you simultaneously take oral hormonal birth control pills and Mounjaro during the first four weeks of treatment and four weeks following a dose increase. Talk to your doctor about switching to non-oral contraception like a patch or vaginal ring, or using barriers like condoms to avoid unplanned pregnancy.

4. Antiretrovirals

Specific medications that manage HIV may also interfere with contraceptive options through drug-drug interactions (DDIs). Taking meds that inhibit cytochrome P450 enzymes — like protease inhibitors — can lead to increased exposure to pregnancy hormones, which may lead to failure. However, some choices are unaffected by DDIs, such as:

• Depot medroxyprogesterone acetate injectable
• Levonorgestrel-releasing intrauterine device
• Copper intrauterine device

These medical terms are a mouthful, but they’re all simply alternative contraception methods. Learning about them can help expand your knowledge of green-light options to avoid pregnancy. It also enables you to keep up with the information your contraceptive providers give.

5. Antifungal Medications

Surprisingly, antifungal doses can likewise reduce the performance of contraceptives. However, only a few have this side effect. One confirmed drug is griseofulvin, which treats fungal infections in the feet, scalp, skin, toenails and other body parts. Alternatives to sidestep the interactions include non-oral medications, such as antifungal creams, powders and ointments.

6. Herbal Medicines

Besides medications, herbal remedies can also make you conceive unexpectedly. A drug interaction may occur with St. John's wort — a natural cure for regulating mood and often recommended to reduce antidepressive symptoms. Like HIV medications, it’s due to the induction of cytochrome P450 — specifically the CYP3A4 isoenzyme — that can cause bleeding and accidental conception. Other herbal medicines with the same effect and which you should avoid are:

• Licorice
• Alfafa
• Marijuana and cannabis
• Black Cohosh
• Ginseng
• Kava-Kava
• Saw Palmetto
• Sene
• Soybeans

Lesser-Known Medications That Can Interfere with Birth Control Pills

Although the risk of pregnancy is low, these drugs can also slightly impede how reproductive control works.

7. Antidepressants

It’s generally safe to take antidepressants and contraceptive pills simultaneously. However, types like selective serotonin reuptake inhibitors may affect hormone levels and weaken the efficacy of the other medication.

Additionally, tricyclic antidepressants — such as amitriptyline or nortriptyline — may have similar outcomes. These drugs are now less commonly prescribed, but inform your doctor in case they write a script that includes them. Give your provider a list of the medications you're taking so they can evaluate for any unfavorable effects.

8. Antiemetics

Some antiemetic drugs that treat nausea and vomiting may fail your anti-contraceptive measures. Neurokinin-1 (NK-1) receptor blockers are medications that reduce vomiting in cancer patients as a side effect of chemotherapy. They can help improve symptoms of depression, anxiety and emesis but also diminish the function of contraceptives. It's recommended for those taking birth control doses to switch to a non-hormonal method.

Importance of Consulting Your Healthcare Provider

Your doctor can guide you in managing drug interactions. Be sure to check with them if you want to combine your current medications with contraceptive pills to avoid mistimed pregnancy.

References:

1. Aronson JK, Ferner RE. (2021, June 1). Analysis of Reports of Unintended Pregnancies Associated With the Combined Use of Non-enzyme-Inducing Antibiotics and Hormonal Contraceptives. BMJ Evidence-Based Medicine. https://ebm.bmj.com/content/26/3/112
   
   
2. Wyllie E, Fesler J. ( 2021, July 7). Counseling Women With Epilepsy About Birth Control Options. Cleveland Clinic. https://consultqd.clevelandclinic.org/counseling-women-with-epilepsy-about-birth-control-options
   
   
3. Centers for Disease Control and Prevention. (2022, May 17). Adult Obesity Facts. Overweight and Obesity. https://www.cdc.gov/obesity/data/adult.html
   
   
4. Weiser P. (2023, September 27). Mounjaro and Pregnancy, Breastfeeding, and Birth Control. Medical News Today. https://www.medicalnewstoday.com/articles/drugs-mounjaro-reproductive-heath
   
   
5. Faculty of Sexual and Reproductive Healthcare. (2023, February 7). Clinical Guidance: Drug Interactions Between HIV Antiretroviral Therapy (ART) and Contraception. Faculty of Sexual and Reproductive Healthcare. https://www.fsrh.org/standards-and-guidance/documents/fsrh-ceu-guidance-drug-interactions/
   
   
6. Yaacoub N. (2022, September 20). Common Basic Medical Terminology. AIMS Education. https://aimseducation.edu/blog/all-essential-medical-terms
   
   
7. University of New Hampshire. (2020, February 29). Oral Contraceptives Handout. https://www.unh.edu/health/sites/default/files/media/2020-02/OralContraceptivesHandout_0.pdf
   
   
8. Valmiro DJ, Pinto LM, Barbosa LN, de Araújo LBC, Gonzaga RV. (2021, October 16). Drug Interactions Between Herbal Medicines and Oral Contraceptives. Research, Society and Development. https://rsdjournal.org/index.php/rsd/article/download/21331/19012/258250
   
   
9. Fetters KA. (2024, February 18). Can You Take Antidepressants While on Birth Control? Parents. https://www.parents.com/pregnancy/my-body/is-it-safe/antidepressants-and-birth-control-pills/
   
   
10. Sharkey L. (2021, June 11). How to Navigate Hormonal Birth Control and Antidepressants. Healthline. https://www.healthline.com/health/birth-control/birth-control-and-antidepressants
    
    
11. Ibrahim MA. (2024, January 11). Antiemetic Neurokinin-1 Receptor Blockers. NIH. https://www.ncbi.nlm.nih.gov/books/NBK470394/