Periods and catamenial epilepsy

On this page we talk about the effect that epilepsy can have on your periods and monthly (menstrual) cycle.

We also talk about catamenial epilepsy. This is when there is an increased risk of seizures at certain times in your monthly cycle.

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Will epilepsy affect my periods?

Your monthly (menstrual) cycle starts on the first day of your period and ends on the day before your next period. Most women have a cycle of between 23 and 35 days and release an egg (ovulate) around 10-16 days before their next period.

Many things can affect your monthly cycle. Reasons for this may include your age, over–exercising, stress and some health problems. Epilepsy and the number of seizures you have, or your epilepsy medicine can also affect your periods. You might notice that your periods don’t follow a pattern. Or they might happen very rarely. And research has shown that polycystic ovary syndrome can affect women taking some epilepsy medicines, particularly sodium valproate.

If your periods don’t follow a pattern, happen rarely, or are very heavy, it’s a good idea to talk to your GP. If they think your epilepsy medicine could be affecting your periods, they might refer you to an epilepsy specialist, neurologist, or gynaecologist.

The NHS has information about irregular periods and other period problems on their website.

Epilepsy Action also has more information about epilepsy and hormones.

Will my periods affect my epilepsy?

You might notice that you have more seizures than usual at certain times in your monthly cycle. This might be at the start of your period, around the middle of your cycle (when you ovulate) or in the week before your period.

When there is a regular pattern to this happening it’s known as catamenial epilepsy.

What is catamenial epilepsy?

Catamenial epilepsy is defined as a pattern of seizures that worsen at certain times of the menstrual cycle. It’s thought this might be because of changes in the levels of the hormones oestrogen and progesterone during the monthly cycle.

Catamenial epilepsy can happen with focal and generalised epilepsies.

Recent studies suggests that catamenial epilepsy could affect around 4 in 10 women with epilepsy. Some studies have shown that catamenial epilepsy might also be a factor if you have drug resistant (refractory) epilepsy.

Some professionals might call it cyclical epilepsy.

Research has shown that there are 3 main times when there is a risk of increased seizures in catamenial epilepsy:

  • In the days leading up to and including menstruation
  • When an egg is released from the ovaries (ovulation)
  • After ovulation in what’s known as the luteal phase

Recent research has also shown that it is still possible to have catamenial epilepsy if you don’t release an egg (ovulate).

How is catamenial epilepsy diagnosed?

There aren’t any tests that can confirm catamenial epilepsy and it can be difficult to diagnose. It might be diagnosed if you have twice as many seizures at similar times of your monthly cycle, usually over the space of 3 months.

If you think you may have catamenial epilepsy, keep a diary of your monthly cycle and seizures for three months. This will help you to see if there is a pattern.

If your periods are irregular, it might be more difficult to track what is happening with your monthly cycle. Keeping a diary can help you to see if there are any patterns.

Your doctor or specialist may also suggest screening your hormone levels and using ovulation kits. These can help to decide if there is a relationship between your seizures and monthly cycle.

Some research suggests that tracking body temperature may also be helpful.

It can help to keep track of these things and avoid other seizure triggers if you can while you are doing this.

Epilepsy Action has a seizure diary you can download.  There may also be apps available to help you do this.

Talk to your epilepsy specialist about any patterns you are noticing.

What is the treatment for catamenial epilepsy?

Seizures associated with catamenial epilepsy may be difficult to control with your usual epilepsy medicines.

If your doctor thinks you have catamenial epilepsy, they might prescribe an extra medicine for you to take. The best medicine to try may depend on whether you have regular or irregular periods.

Treatments for catamenial epilepsy include:

  • A medicine such as clobazam (Frisium) to take on the days that you are at risk of having seizures.
  • Treatment with hormones

At the moment there isn’t any conclusive evidence to say that treatment with hormones is effective for catamenial epilepsy but research is ongoing.

Further studies are needed to find effective treatments for catamenial epilepsy.

If you are prescribed hormone treatments, it’s important to check if there are any interactions with your regular epilepsy medicines.

“At 26 I had my second daughter and when she was about 6 months old, due to my hormones changing, I started having monthly tonic clonic seizures on the same day of the month (catamenial epilepsy). I was put on medication and I was very lucky in that the first dose worked straight away and didn’t cause any side effects. Provided I limited my alcohol intake and made sure I had a regular sleep pattern, I was consistently controlled for ten years.” – Hayley

Premenstrual syndrome

Premenstrual syndrome (PMS) affects many women. It can make you feel bloated, stressed and anxious in the days leading up to your period. If PMS makes you feel stressed or anxious, these can be triggers for seizures and you might notice that you have more seizures at this time.

Epilepsy Action has information about looking after your wellbeing.

The NHS has information about premenstrual syndrome and support that might be available.

Take steps to help your wellbeing

Epilepsy and your wellbeing

Taking steps to improve your wellbeing will help you to manage the impact of epilepsy in your life.

This course will help you understand the relationship between epilepsy and wellbeing, and provide you with simple, practical advice to help you feel and function at your best.

Take this course
This information has been produced under the terms of the PIF TICK. The PIF TICK is the UK-wide Quality Mark for Health Information. Please contact if you would like a reference list for this information.
Published: July 2020
Last modified: January 2024
To be reviewed: January 2027
Tracking: A057.09 (previously B017)
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