Birth control interactions occur when medications or supplements affect how well contraception works or increase side effects. These interactions vary depending on the type of birth control you use.

Certain medications and supplements can interact with birth control. Some may make hormonal methods less effective, while others can increase side effects such as dizziness, headaches, or mood changes.

These interactions can vary depending on the type of birth control you use, such as pills, patches, rings, injections, or implants, as well as the specific medication or supplement involved.

This article explains how birth control interactions happen, what to watch for, and when to speak with a doctor.

Birth control interactions happen when another medication or supplement affects how contraceptives work in the body. Most documented interactions involve hormonal birth control, which relies on consistent hormone levels to prevent pregnancy.

Research suggests that some medications can speed up how quickly the body breaks down birth control hormones, which can lower hormone levels and reduce effectiveness. This can increase the risk of unintended pregnancy.

Other medications can interfere with hormone absorption in the gut or how hormones circulate in the body, increasing the likelihood of side effects in some people. As a result, birth control interactions may lead to:

Because interactions vary by medication and type of birth control, it’s important to review any new prescriptions or supplements with a healthcare professional.

Some medications can reduce the effectiveness of hormonal birth control, increasing the risk of unintended pregnancy. Medications known to reduce effectiveness include:

Antibiotics

Evidence remains limited and inconsistent for most antibiotics. Rifampin and rifabutin are the only antibiotics consistently shown to reduce the effectiveness of hormonal birth control.

These antibiotics make the body break down estrogen and progestin faster, lowering hormone levels needed to prevent pregnancy.

Other antibiotics such as tetracyclines, azithromycin (Zithromax), and erythromycin may also interfere with hormonal contraceptive effectiveness, though research on these is limited.

If you’re not sure whether a specific antibiotic could affect your birth control method, a healthcare professional can help guide you.

Antiseizure medications

Research shows that some antiseizure medications increase liver enzyme activity, which speeds up the breakdown of hormonal birth control and lowers hormone levels.

Examples of these medications include:

HIV medications

Certain antiretroviral medications may affect how hormones are processed in the liver, which can lower hormone levels and reduce contraceptive effectiveness.

Examples include:

  • efavirenz (Sustiva)
  • some protease inhibitors, such as lopinavir/ritonavir (Kaletra)

However, protease inhibitors have not been consistently linked to reduced contraceptive effectiveness.

Herbal supplements

Some herbal supplements, such as St. John’s wort, can increase liver enzyme activity, which may lower hormone levels and raise the risk of breakthrough bleeding or unintended pregnancy.

According to the Centers for Disease Control and Prevention (CDC), the level of interaction can vary depending on the dose and the concentration of active ingredients in different St. John’s wort products.

If you take any of these medications, a healthcare professional may recommend:

  • using a backup method, such as condoms
  • switching to a nonhormonal option, like a copper IUD
  • adjusting your birth control method during treatment

Always talk with a doctor or pharmacist before combining new medications with hormonal birth control, especially if you want to avoid an unintended pregnancy.

Research suggest that some medications may increase side effects when taken with hormonal birth control, including:

  • Caffeine and stimulant medications: Birth control slows caffeine breakdown, which may worsen anxiety, jitteriness, or headaches in some people.
  • Corticosteroids: Hormonal birth control may slow the breakdown of certain corticosteroids, such as prednisone, which can increase the risk of side effects like fluid retention or mood changes in some people.
  • Melatonin: When taken together, hormonal birth control may affect sleep patterns, which some people report as increased drowsiness or grogginess.
  • Antidepressants: Tricyclic antidepressants like amitriptyline may clear more slowly with hormonal birth control, increasing side effects, such as dizziness or drowsiness.
  • Benzodiazepines: Hormonal contraceptives may slow the metabolism of drugs like diazepam (Valium) and alprazolam (Xanax), increasing sedation or slowed reaction time.

These side effects vary by medication and dose. If symptoms become bothersome, a healthcare professional can help adjust your treatment or birth control method.

Nonhormonal birth control methods generally do not interact with medications, since they don’t rely on hormones to prevent pregnancy.

Common options include:

Because these methods work through physical barriers, sperm prevention, or cycle tracking, medications don’t affect their reliability.

One possible exception is spermicides. Some medications used to treat vaginal yeast infections may reduce how well spermicides work.

Talk with a doctor or pharmacist if you:

  • start a new medication or supplement
  • take herbal products regularly
  • notice breakthrough bleeding or unexpected spotting
  • use antiseizure, HIV, or tuberculosis medications
  • have liver conditions that affect hormone processing

If a medication interacts with your birth control, a healthcare professional may:

  • recommend a temporary backup method
  • switch you to a nonhormonal option, such as a copper IUD
  • adjust your medication or birth control type
  • help you plan around short-term interactions

Pharmacists are also a helpful resource and can quickly check for interactions when filling prescriptions.

Several medications and supplements can change how hormonal birth control works or increase side effects. Understanding these interactions helps you avoid unintended pregnancy and manage symptoms more effectively.

If you use birth control and start a new medication, check with a doctor or pharmacist. A quick conversation can help you choose the safest option and stay protected.