Decisions about starting birth control and choosing a birth control method can be challenging. If you have epilepsy, your choice requires even more thought because some anti-seizure medicines can make some types of birth control less reliable and increase your risk of an unplanned pregnancy.
Why is contraception important?
If you are taking anti-seizure medicine and are a woman of child-bearing age, it is important that you also use contraception. If a method of contraception does not work well, this can lead to pregnancy, which can be a problem because some anti-seizure medicines like sodium valproate, can harm your baby. The risk of harm to the baby from anti-seizure medicine use during pregnancy is highest in the first trimester (first 12 weeks of pregnancy), before many women realise they are pregnant. Read more about epilepsy and pregnancy.
It is best to use two forms of contraception, usually one of the options in the table below plus condoms. If you are taking an oral contraceptive, make sure you know what to do if a dose is missed or if you are sick with vomiting (being sick) or diarrhoea (runny poo/hamuti).
How well does contraception work?
Intrauterine devices (IUD) and medroxyprogesterone acetate injection (Depo Provera) are not affected by anti-seizure medicine. While condoms are not affected by anti-seizure medicine, they are the least reliable birth control if used by themselves. They are more effective if used with another method of contraception.
Intrauterine device (IUD)
- Very reliable – fewer than 1 in every 100 women (1%) become pregnant during one year of typical use.
- It is not affected by anti-seizure medication.
- An IUD is a small, T-shaped plastic device that is inserted into your uterus (womb) and has a plastic string tied to the end which hangs down through the cervix into the vagina.
- In Aotearoa New Zealand, there are 2 types of IUDs: progestogen or hormonal IUDs (such as Mirena®, Jaydess®) and copper IUD. Read more about IUDs.
Medroxyprogesterone acetate injections (Depo Provera)
- About 6 in every 100 women (6%) become pregnant during 1 year of typical use.
- It is not affected by anti-epilepsy medication.
- Depo Provera is given as an injection, every 12 weeks (every 3 months).
- Read more about Depo Provera.
- Very reliable – fewer than 1 in every 100 women (1% become pregnant during one year of typical use.
- This option is NOT recommended if you are taking carbamazepine, phenytoin, oxcarbazepine, phenobarbital, primidone, rufinamide, or topiramate.
- The contraceptive implants are small rods (about the size of a matchstick) that contain progesterone. These rods are placed under the skin, in the inside of your arm (you can feel the rods under your skin). Read more about implants.
Combined hormonal oral contraceptive (COC) pill
- About 8 in every 100 women (8%) become pregnant during 1 year of typical use.
- This option is NOT recommended if you are taking carbamazepine, phenytoin, lamotrigine, oxcarbazepine, phenobarbital, primidone, rufinamide, topiramate.
- The effectiveness of the COC pill is highly dependent on taking it every day, whether you have sex on that day or not.
- If you are taking an oral contraceptive, make sure you know what to do if a dose is missed or if you are sick with vomiting or diarrhoea. Read more about combined hormonal oral pill.
Progestogen-only pill (POP)
- About 9 in every 100 women (9%) become pregnant during 1 year of typical use.
- This option is NOT recommended if you are taking carbamazepine, phenytoin, oxcarbazepine, phenobarbital, primidone, rufinamide or topiramate.
- The effectiveness of the POP is highly dependent on taking it every day. Read more about progesterone-only pill.
- Very unreliable – about 18 in every 100 women (18%) become pregnant during 1 year of typical use.
- If you are taking anti-seizure medicine, it is best to use one of the options above together with condoms.
Emergency contraceptive pill (the ‘morning after pill’)
The ‘morning after pill’ is a form of emergency contraception that can be taken within 72 hours after sex. It can be used if you have unprotected sex, if you have missed a dose of the pill or if a condom breaks.
- Some anti-seizure medication can affect the morning-after pill, eg, carbamazepine, phenytoin, oxcarbazepine, phenobarbital, primidone, rufinamide, topiramate.
- The dose of the morning after pill will need to be doubled. However, this is an unapproved dose and the effectiveness of this option has not been fully studied.
- A copper IUD is recommended for emergency contraception for women taking these anti-seizure medicines.
- Read more about emergency contraception and how do I choose the right emergency contraception for me?
Do contraceptives increase the chance of seizures?
Non-hormonal contraceptive methods (such as condoms, diaphragms, and IUDs) do not affect seizure control. The effect of hormonal contraception (such as the combined oral contraceptive, mini pill or progestogen only pill) and implants on seizure control varies among women.
- Some women find that hormonal birth control increases their number of seizures while other women find it decreases their seizures, or has no effect on their seizures at all.
- If you are unsure of the effect of your birth control method on your seizures, look for signs that your epilepsy medication is not working, such as changes in the number, length, or kind of seizures you usually have. Talk to your doctor about this.
If you are planning a pregnancy
If you decide you would like to get pregnant, it is important to plan your pregnancy 6–12 months before you start trying to get pregnant. Anti-seizure medicines can harm an unborn child and the risks are higher with some medicines, combinations of medicines and at higher doses. Talk to your doctor and agree on a plan about how to manage your anti-seizure medicines and your dose. Read more about how medicines for epilepsy, mental health and pain can harm your unborn baby.
Folic acid tablets are recommended from 4 weeks before, to at least 12 weeks after conception to reduce the risk of harm to your baby from neural tube defects. A higher than usual dose of folic acid (5 mg per day) is recommended for women taking anti-seizure medicines. Folic acid reduces the risk of harm from neural tube defects but does not reduce other harmful effects of anti-seizure medicines to the baby. Read more about folic acid.
Contraception Epilepsy NZ
Planning for a baby Epilepsy NZ
Epilepsy and women Epilepsy NZ
Medicines for epilepsy, mental health and pain can harm your unborn baby ACC, NZ
Angela is a pharmacist in the Quality Use of Medicines Team at Waitematā District Health Board. She has experience in hospital pharmacy in New Zealand and in the UK, and was previously a medical writer for Elsevier in The Netherlands. Angela is interested in promoting the safe use of medicines, particularly high-risk medicines.