Hormonal Contraception and Epilepsy: The Birth Control Guide Your Doctor Should Give You

For women with epilepsy, choosing contraception requires careful consideration. Some anti-seizure medications (ASMs) can reduce the effectiveness of hormonal contraception, and some contraceptives may interact with epilepsy treatment. Understanding these interactions is essential to prevent unplanned pregnancy and make informed choices.

The Problem: Why Some Anti-Seizure Medications Affect Contraception

Certain anti-seizure medications (ASMs) are enzyme-inducing drugs. This means they speed up the liver’s processing of other medications, including hormonal contraceptives.

When hormonal contraception is broken down more quickly than intended, hormone levels in the bloodstream drop. This can reduce or eliminate contraceptive effectiveness, significantly increasing the risk of unplanned pregnancy.

The key concern: You may be taking contraception correctly and still become pregnant if you are on an enzyme-inducing ASM.

Which Anti-Seizure Medications Affect Contraception?

Enzyme-Inducing ASMs (Reduce Contraceptive Effectiveness)

The following anti-seizure medications are known to reduce the effectiveness of hormonal contraception:

• Carbamazepine
• Eslicarbazepine
• Oxcarbazepine
• Perampanel (at doses of 12mg per day or higher)
• Phenobarbital
• Phenytoin
• Primidone
• Rufinamide
• Topiramate (at doses of 200mg per day or higher)

If you take any of these medications, standard-dose hormonal contraception may not be reliable.

Non-Enzyme-Inducing ASMs (Do Not Affect Contraception)

The following anti-seizure medications do not reduce contraceptive effectiveness:

• Brivaracetam
• Ethosuximide
• Gabapentin
• Lacosamide
• Lamotrigine
• Levetiracetam
• Piracetam
• Pregabalin
• Sodium valproate
• Tiagabine
• Vigabatrin
• Zonisamide

If you take one of these medications, standard hormonal contraception should work as expected.

Important note: Lamotrigine levels can be reduced by some hormonal contraceptives containing oestrogen. This does not make contraception less effective, but it may reduce seizure control. Discuss this with your neurologist.

Which Contraceptive Methods Are Affected?

Enzyme-inducing ASMs reduce the effectiveness of contraceptives that rely on hormones circulating in the bloodstream.

Affected Methods (Less Reliable with Enzyme-Inducing ASMs)

• Combined oral contraceptive pill (the pill)
• Progestogen-only pill (mini pill)
• Contraceptive patch
• Vaginal ring
• Contraceptive implant (such as Nexplanon)

If you are taking an enzyme-inducing ASM, these methods may not provide adequate pregnancy protection.

Methods That Remain Reliable

The following contraceptive methods are not affected by enzyme-inducing ASMs and remain effective:

• Intrauterine device (IUD) – copper coil (hormone-free)
• Intrauterine system (IUS) – hormonal coil (such as Mirena) – works locally in the uterus, so liver metabolism does not affect it
• Contraceptive injection (Depo-Provera) – may need more frequent dosing; discuss with your GP
• Barrier methods – condoms, diaphragm, cervical cap (always reliable when used correctly)
• Permanent methods – sterilisation (male or female)

These methods provide reliable contraception regardless of which anti-seizure medication you take.

What About Higher-Dose Pills?

Some healthcare providers may suggest a higher-dose combined pill (50 micrograms of oestrogen instead of the standard 30-35 micrograms) for women on enzyme-inducing ASMs.

Important considerations:

• This is an off-license use (the pill is not officially approved for this purpose)
• Evidence for effectiveness is limited
• It may not provide full protection
• Other reliable methods are often preferred

If this option is discussed, ensure you fully understand the level of protection it provides and consider whether a more reliable method might be preferable.

Emergency Contraception Considerations

If you need emergency contraception and you take an enzyme-inducing ASM, standard emergency contraception may be less effective.

Options

Copper IUD: The most reliable emergency contraception. Can be fitted up to 5 days after unprotected sex and is unaffected by anti-seizure medications.

Levonorgestrel pill (Levonelle): If using this, a double dose (3mg total instead of 1.5mg) is recommended for women on enzyme-inducing ASMs. Discuss with a pharmacist or doctor.

Ulipristal acetate (ellaOne): May be less effective if you take enzyme-inducing ASMs. The copper IUD is a more reliable option.

Discussing Contraception with Your Neurologist and GP

Contraceptive decisions when you have epilepsy require coordination between your neurologist and GP (or sexual health clinic).

Questions to Ask Your Neurologist

• Does my current anti-seizure medication affect contraception?
• If I want to use hormonal contraception, could we switch to a non-enzyme-inducing ASM?
• Are there any seizure-related risks with my chosen contraceptive method?
• Will hormonal contraception affect my seizure control?

Questions to Ask Your GP or Sexual Health Clinic

• Which contraceptive methods are most reliable with my current anti-seizure medication?
• Can you prescribe or fit a long-acting method such as an IUD or IUS?
• What should I do if I need emergency contraception?
• How will contraception interact with my epilepsy treatment?

Bring a list of your current medications to every appointment. This ensures all healthcare professionals have the information they need.

Switching Anti-Seizure Medications to Protect Contraception

If you are on an enzyme-inducing ASM and want to use hormonal contraception, one option may be switching to a non-enzyme-inducing ASM.

Important considerations:

• Changing anti-seizure medications is a significant decision and must be discussed thoroughly with your neurologist
• Switching medication carries risks, including breakthrough seizures
• The decision must balance seizure control with contraceptive reliability
• Some people cannot switch due to their specific epilepsy type or previous medication failures

This option is not suitable for everyone, but it is worth discussing if contraception reliability is a high priority.

Pregnancy Planning: When You’re Ready

If and when you decide you want to become pregnant, planning ahead is essential.

Steps to Take

At least 3-6 months before trying to conceive:

• Book a pre-conception appointment with your neurologist
• Discuss whether your current anti-seizure medication is appropriate for pregnancy (some ASMs carry higher risks of birth defects)
• Start high-dose folic acid (5mg daily, available on prescription)
• Review seizure control and medication doses

Stopping contraception:

• Do not stop contraception until you have had the pre-conception discussion with your neurologist
• Unplanned pregnancy on certain anti-seizure medications carries risks
• Switching medications may be recommended before conception

Planning ahead ensures the safest possible pregnancy for both you and your baby.

Real Consequences: Why This Matters

Unplanned pregnancy while taking certain anti-seizure medications can carry increased risks of birth defects. Sodium valproate, in particular, carries significant risks and should not be taken during pregnancy unless absolutely necessary.

The MHRA (Medicines and Healthcare products Regulatory Agency) has issued specific guidance that women and girls of childbearing potential on sodium valproate must be enrolled in a pregnancy prevention programme and use highly effective contraception.

Reliable contraception protects both your health and your choices. Taking control of contraceptive decisions ensures that if you do become pregnant, it is planned and your medication has been optimised in advance.

Key Points to Remember

• Some anti-seizure medications reduce the effectiveness of hormonal contraception
• Enzyme-inducing ASMs interact with the pill, patch, ring, and implant
• Copper IUD, hormonal IUS, and contraceptive injection remain reliable
• Discuss contraception with both your neurologist and GP
• Emergency contraception may need higher doses if you take enzyme-inducing ASMs
• Pre-pregnancy planning is essential for safe outcomes
• Lamotrigine levels may be affected by oestrogen-containing contraception

If you are unsure which anti-seizure medication you take or whether it affects contraception, check with your neurologist or pharmacist. Never assume your contraception is working without confirming it is appropriate for your specific epilepsy treatment.

Reliable contraception is a critical part of managing epilepsy safely. Make sure you have the information and support needed to make informed choices that work for your individual circumstances.