Valproic acid

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Valproic acid is used to treat bipolar disorder.

It's occasionally used to prevent migraine headaches and can also be used to treat epilepsy.

This medicine is only available on prescription. It comes as capsules or tablets.

It's not recommended for girls or women who may become pregnant. Your doctor will put you on Prevent, the valproate pregnancy prevention programme.

NHS coronavirus advice

While everyone is staying at home as much as possible, it can be hard to know what to do if you need medical help.

If you are taking valproic acid, get advice now if you think you are pregnant or might become pregnant. The valproate pregnancy prevention programme is important and is still running.

Your doctor or nurse will talk to you on a video call or phone call. They can also arrange safe visits to see you, if you need them to.

If you usually have an annual review with your specialist, this can also be done as a video or phone call. Do not delay this important appointment.

Updated: 26 May 2020


  • It's usual to take valproic acid 2 or 3 times a day. You can take it with or without food.
  • If you're pregnant, or there's a chance you could become pregnant, valproic acid is not recommended for bipolar disorder or migraine. For epilepsy, your doctor will only prescribe valproic acid for you if there are no other suitable treatments.
  • You'll usually start on a low dose. Your dose will gradually increase over a few days or weeks.
  • Sodium valproate and semisodium valproate are similar to valproic acid and work in the same way. However, these medicines are used to treat different illnesses and doses will vary.
  • There are also brands such as Epilim Chrono and Epilim Chronosphere which contain mostly sodium valproate, with some valproic acid.


Valproic acid can be taken by adults and children to treat bipolar disorder or epilepsy.

It can be taken by adults (aged 18 and above) to prevent migraine.

Valproic acid is not suitable for some people:

  • women who could become pregnant – unless they're on Prevent, the valproate pregnancy prevention programme
  • younger women or girls who are having sex (even if their periods haven't started) – unless they're on Prevent, the valproate pregnancy prevention programme

If you're pregnant, do not take valproic acid to treat bipolar disorder or to prevent migraines. This is because valproic acid can seriously harm an unborn child.

For treating epilepsy during pregnancy, your doctor will only prescribe valproic acid for you if no other treatments work.

To make sure valproic acid is safe for you, tell your doctor if you:

  • have ever had an allergic reaction to valproic acid or other medicines in the past
  • have liver problems
  • have a rare metabolic or genetic illness such as porphyria, urea cycle disorder or mitochondrial disorder
  • are pregnant or trying to get pregnant


Valproic acid is a prescription medicine. It's important to take it as advised by your doctor.


The usual dose for treating:

  • bipolar disorder in adults: the usual dose is 750mg to 2,000mg a day, split into 2 or 3 doses
  • bipolar disorder in children: the doctor will work out the right dose for your child
  • migraine in adults: daily doses vary from a single dose of 400mg to 1,500mg split into 2 doses
  • epilepsy in adults and older children (aged 12 years and over): the usual dose is 600mg to 2,000mg a day, split into 2 to 4 doses
  • epilepsy in younger children (weighing more than 20kg): doses vary. The doctor will use your child's weight to work out the right amount of medicine to give them

If you need to take your medicine a few times a day, the amount you take each time depends on your total daily dose. You'll take a number of equal doses that add up to your daily total. Ask your doctor or a pharmacist if you're unsure how much to take each time.

If you're taking valproic acid and also have kidney problems, your doctor may prescribe a lower dose.

How and when take it

Valproic acid comes as "gastro resistant" tablets and capsules. These release the valproic acid into your body as soon as they pass through your stomach.

Swallow the tablets or capsules whole with a drink of water or juice. Do not chew them.

You can take valproic acid with or without food, but it’s best to do the same each time.

Gastro resistant tablets – you'll usually take these 2 to 3 times a day. Gastro resistant capsules – you'll usually take these 2 to 4 times a day.

If you're taking valproic acid twice a day, try to leave a gap of 10 to 12 hours between doses. For example you could take your first dose in the morning (between 7am and 8am) and a second dose in the evening (between 7pm and 8pm).

If you take your medicine 3 to 4 times a day, try to space your doses evenly through the day. If you need to take 3 doses, for example, you could take your medicine first thing in the morning, early afternoon and bedtime.

Will my dose go up or down?

To prevent the chance of side effects, your doctor will start you off on a low dose of valproic acid. They will increase it gradually over a few days or weeks.

Once you find a dose that suits you, it will usually stay the same, unless your condition changes, or your doctor starts you on a new medicine that may interfere with valproic acid.

What if I forget to take it?

If you forget a dose take it as soon as you remember, unless it's less than 2 hours to your next dose. In this case, skip the missed dose and take your next one at the usual time.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

If you have epilepsy, it’s important to take this medicine regularly. Missing doses can trigger a seizure.

If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Taking too much valproic acid can lead to symptoms such as:

  • feeling or being sick (nausea or vomiting)
  • headaches, or feeling dizzy
  • muscle weakness
  • breathing problems
  • feeling confused, or changes to your normal behaviour
  • passing out


Like all medicines, valproic acid can cause side effects, although not everyone gets them.

Common side effects

These common side effects may happen in more than 1 in 100 people. They're usually mild and go away by themselves.

Keep taking the medicine but talk to your doctor if these side effects bother you or don't go away:

  • stomach pain, feeling or being sick (nausea or vomiting)
  • diarrhoea
  • dry or sore mouth, or swollen gums
  • shakes (tremors) in a part of your body, or unusual eye movements
  • feeling tired or sleepy
  • headache
  • weight gain
  • thinning hair, or changes to the colour or texture of your hair
  • irregular or delayed periods

Serious side effects

It's unusual to have serious side effects after taking valproic acid. Tell a doctor straight away if you have:

  • thoughts of harming or killing yourself – a small number of people taking valproic acid have had suicidal thoughts
  • yellowing of your skin or whites of your eyes – these may be warning signs of liver problems
  • long-lasting and severe nausea, vomiting or stomach pain – these may be warning signs of an inflamed pancreas
  • unusual bruises or bleeding – these may be warning signs of a blood disorder

Serious allergic reaction

In rare cases, valproic acid may cause a serious allergic reaction (anaphylaxis).

These are not all the side effects of valproic acid. For a full list, see the leaflet inside your medicine packet.


What to do about:

  • stomach pain, feeling or being sick (nausea or vomiting) – take valproic acid with or after a meal or snack. It may also help if you don't eat rich or spicy food.
  • diarrhoea – have small but frequent sips of water. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
  • dry or sore mouth, or swollen gums – for a dry mouth try sugar-free gum or sweets, or sipping cold drinks. If this does not help, or you have mouth ulcers, talk to your pharmacist or doctor. If you're bothered by swollen gums or this symptom doesn't go away, talk to your doctor or dentist.
  • shakes (tremors) in a part of your body, or unusual eye movements – talk to your doctor if this is bothering you. These symptoms can be a sign that the dose is too high for you. It may help to change your dose or take your medicine at a different time of day.
  • feeling tired or sleepy – as your body gets used to valproic acid, these side effects should wear off. If these symptoms do not get better within a week or two, your doctor may either reduce your dose or increase it more slowly. If that doesn't work you may need to switch to a different medicine.
  • headaches – make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller. Talk to your doctor if your headaches last longer than a week or are severe.
  • weight gain – if you find you're putting on weight after taking valproic acid, try to have a healthy balanced diet. Regular exercise will also help you keep your weight stable. Your doctor will usually monitor your weight while you're taking this medicine. Speak to them if you have any concerns.
  • thinning hair, or changes to the colour or texture of your hair – if these symptoms bother you, ask your doctor whether it's possible to lower your dose. Your hair may regrow after either reducing your dose or switching to a different medicine.
  • irregular or delayed periods – if you usually have regular periods, tell your doctor straight away if your period is late. As well as being a side effect of valproic acid, it's a sign that you could be pregnant, and valproic acid can be harmful for an unborn baby. Changes to your periods can also be a symptom of polycystic ovary syndrome (PCOS), a rare side effect of valproic acid. Your doctor will be able to do some tests to check whether you have PCOS.


Valproic acid is generally not recommended in pregnancy, as it can harm your unborn baby. If there's a chance you could become pregnant while taking this medicine, your doctor will put you on Prevent, the valproate pregnancy prevention programme.

If you think you might already be pregnant, contact your doctor or nurse as soon as possible.

If you're taking valproic acid for epilepsy and you become pregnant, do not stop taking your medicine without talking to your doctor first. This is because your symptoms or seizures may get worse.

Your doctor may continue to prescribe valproic acid, but only if there's no other suitable treatment for your epilepsy.

For more information about how valproic acid can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPS) website.

Valproic acid and breastfeeding

Small amounts of valproic acid pass into your breast milk. As the amount is so small it's unlikely to harm your baby, unless your baby was born premature or has kidney problems.

Talk to your doctor about the benefits and risks of taking valproic acid while breastfeeding. They may still recommend valproic acid if it's the only medicine that works for you.


There are some medicines that may interfere with how valproic acid works. Valproic acid can also affect the way other medicines work.

Tell your doctor if you're taking (or before you start taking):

Mixing valproic acid with herbal remedies or supplements

It's not possible to say whether complementary medicines and herbal supplements are safe to take with valproic acid.

They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.


Page last reviewed: 24/09/2018
Next review due: 24/09/2021