1. About valproic acid
Valproic acid is usually used to treat bipolar disorder.
Some brands are used to treat epilepsy. It can also be used to prevent migraine.
This medicine is only available on prescription. It comes as capsules or tablets.
If taken during pregnancy, valproic acid can cause problems for a baby's development, including birth defects and long term learning difficulties. For this reason, valproic acid is not recommended if there's a chance that you could become pregnant.
For women and girls of childbearing age, if you do need to take valproic acid then your doctor will put you on Prevent, the valproate pregnancy prevention programme.
Important: Valproate pregnancy prevention programme
The valproate pregnancy prevention programme is very important.
You should be reviewed every year by your doctor or nurse. They will assess whether you need to continue taking valproic acid or whether it is possible to change your medicine.
If you do need to continue taking valproic acid then you must be using reliable contraception, even if you are not currently sexually active. Your doctor or nurse can advise you about reliable contraception. You will be asked to sign a form to say that you are using contraception and understand the risks of becoming pregnant while taking valproic acid.
It's important to get advice as soon as possible if you think you are pregnant or might become pregnant while taking valproic acid. However, do not stop taking your medicine suddenly without talking to your doctor first.
Updated: 18 October 2022
2. Key facts
- You'll usually take valproic acid 2 or 3 times a day. You can take it with or without food.
- 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 conditions and doses will vary.
- There are also brands such as Epilim Chrono, Epilim Chronosphere and Dyzantil which contain mostly sodium valproate, with some valproic acid.
- If you're pregnant, or there's a chance you could become pregnant, valproic acid is not recommended for treating migraine. For epilepsy and bipolar disorder, your doctor will only prescribe valproic acid for you if there are no other suitable treatments.
3. Who can and cannot take valproic acid
Adults and children can take valproic acid to treat bipolar disorder or epilepsy.
Adults, aged 18 and above, can take it to prevent migraine.
Valproic acid is not suitable for girls or women who could become pregnant. However, in some cases it may be the only treatment option available, for example, for epilepsy where other treatments have not worked. Girls and women who need to take valproic acid must be on Prevent, the valproate pregnancy prevention programme.
To make sure valproic acid is safe for you, tell your doctor if you:
- have ever had an allergic reaction to valproic acid or any other medicine
- have liver problems
- have a rare metabolic or genetic condition such as porphyria, urea cycle disorder or mitochondrial disorder
4. How and when to take valproic acid
Valproic acid is a prescription medicine. It's important to take it as your doctor tells you.
The usual dose for treating bipolar disorder for:
- adults – 750mg to 2,000mg a day, split into 2 or 3 doses
- children – the doctor will work out the right dose for your child
The usual dose for preventing migraine for:
- adults – 500mg to 1,000mg a day, split into 2 or 3 doses
The usual dose for treating epilepsy for:
- adults and older children (aged 12 years and over) – 600mg to 2,000mg a day, split into 2 to 4 doses
- younger children (weighing more than 20kg) – the doctor will use your child's weight to work out the right dose for them
If you need to take your medicine more than once a day, you'll take 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 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.
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 your second dose in the evening (between 7pm and 8pm).
If you take it 3 to 4 times a day, try to space your doses evenly throughout the day. If you need to take 3 doses, for example, you could take a dose first thing in the morning, early afternoon and bedtime.
Will my dose go up or down?
To reduce 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 often forget doses, 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
Urgent advice: Contact 111 for advice now if:
- you take too much valproic acid and feel unwell
Go to 111.nhs.uk or call 111
If you need to go to A&E, take the valproic acid packet or the leaflet inside it, plus any remaining medicine, with you.
5. Side effects
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 do not go away:
- stomach pain, feeling or being sick
- dry or sore mouth, or swollen gums
- shakes (tremors) in a part of your body, or unusual eye movements
- feeling tired or sleepy
- 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 the whites of your eyes or your skin, although this may be less obvious on brown or black skin, and dark pee – these may be signs of liver problems
- long-lasting and severe nausea, vomiting or stomach pain – these may be signs of acute pancreatitis (an inflamed pancreas)
- unusual bruises or bleeding – these may be signs of a blood disorder
Serious allergic reaction
In rare cases, valproic acid may cause a serious allergic reaction (anaphylaxis).
Immediate action required: Call 999 or go to A&E now if:
- you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
- you're wheezing
- you get tightness in the chest or throat
- you have trouble breathing or talking
- your mouth, face, lips, tongue or throat start swelling
You could be having a serious allergic reaction and may need immediate treatment in hospital.
These are not all the side effects of valproic acid. For a full list, see the leaflet inside your medicine packet.
You can report any suspected side effect using the Yellow Card safety scheme.
6. How to cope with side effects of valproic acid
What to do about:
- stomach pain, feeling or being sick – take valproic acid with or after a meal or snack. It may also help if you avoid rich or spicy food. Take small, frequent sips of water if you're being sick to avoid dehydration.
- diarrhoea – drink plenty of fluids such as water or squash to avoid dehydration. 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 does not 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 your dose is too high. Talk to your doctor as they may want to change your dose or suggest you take it at a different time.
- 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 does not work, talk to your doctor as they may want to switch you 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, take a pregnancy test if your period is late, and speak to your doctor if the result is positive. As well as being a side effect of valproic acid, a late period is 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.
7. Pregnancy and breastfeeding
Valproid acid and pregnancy
Valproic acid is not recommended in pregnancy, as it can cause birth defects and problems with your baby's learning and behaviour.
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 or bipolar disorder and you become pregnant, do not stop taking your medicine without talking to your doctor first. This is because your symptoms may get worse.
Your doctor may continue to prescribe valproic acid, but only if there's no other suitable treatment for your epilepsy or bipolar disorder.
For pregnant women with recurrent migraine your doctor should offer you an alternative treatment to valproic acid.
You must have a review of your treatment every year. Contact your doctor or specialist now if you have not had one.
Valproic acid and breastfeeding
If your doctor or health visitor says your baby is healthy you can take valproic acid while breastfeeding.
Valproic acid passes into breast milk in small amounts but it's unlikely to harm your baby so you can continue breastfeeding if your doctor says you need to take it.
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. Your doctor may still recommend valproic acid if it is the only medicine that works for you.
Do not stop taking your medicine without talking to your doctor first as your symptoms may get worse. Breastfeeding will also benefit both you and your baby.
Talk to your health visitor, midwife, pharmacist or doctor as soon as possible if:
- your baby is not feeding as well as usual
- your baby is bruising more easily than usual
- the whites of your baby's eyes turn yellow or your baby's skin turns yellow (this may be less obvious on brown or black skin), or your baby has dark pee or pale poo – these can be signs of jaundice
- you have any other concerns about your baby
Non-urgent advice: Tell your doctor if you're:
- trying to get pregnant
- Best Use of Medicines in Pregnancy (BUMPS) website – information about how valproic acid can affect you and your baby during pregnancy
- NHS England letter to all women and girls aged 12 to 55 taking sodium valproate (includes valproic acid), available in different languages
- Valproate pregnancy prevention programme patient guide: what women and girls need to know about valproate (PDF, 341kb)
8. Cautions with other medicines
There are some medicines that may affect how valproic acid works. Valproic acid can also affect the way other medicines work.
Tell your doctor if you're taking any of these medicines:
- any other medicines for epilepsy such as carbamazepine
- medicines for preventing blood clots such as warfarin
- aspirin for pain relief or low-dose aspirin
- cimetidine, a medicine for stomach ulcers
- medicines to treat HIV and AIDS such as ritonavir
- antibiotics such as erythromycin
- medicines for depression or other mental health problems such as venlafaxine, quetiapine or diazepam
- cholesterol-lowering medicines such as cholestyramine
- medicines to prevent malaria such as mefloquine or chloroquine
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.
Important: Medicine safety
Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.
9. Common questions about valproic acid
How does valproic acid work?
Valproic acid is an anticonvulsant (or anti-epileptic) medicine.
It's not fully understood how this medicine works for treating bipolar disorder. However valproic acid is thought to reduce or prevent manic episodes by increasing the amount of a chemical called gamma-aminobutyric acid (GABA) in the brain. GABA blocks transmission across nerves in the brain and has a calming effect.
It's not clear how valproic acid prevents migraine. It may limit how your nerves transmit pain signals in the brain.
For treating epilepsy, valproic acid prevents epileptic seizures by reducing excessive electrical activity in your brain.
When will I feel better?
It takes a few weeks for valproic acid to work properly. You may still have symptoms during this time.
How long will I take it for?
Once your condition is under control, you'll usually need to keep taking valproic acid for many years.
Can I get addicted to valproic acid?
Valproic acid is not known to be addictive.
Is it safe to take it for a long time?
Many people can take valproic acid safely for many months or years.
However there are potential side effects that can happen over a long time. Long-term treatment with valproic acid can cause osteoporosis and osteopenia (increasing your risk of breaking a bone).
Your doctor can arrange for tests to check the strength of your bones. Regular exercise and a good diet can also help to keep your bones strong.
Can I get epilepsy medicines for free?
If you have epilepsy, you're entitled to free prescriptions for all of your medicines (not just your epilepsy ones).
To claim your free prescriptions you'll need a medical exemption certificate.
The application form for the medical exemption certificate is called FP92A. You can get this from your doctor's surgery. You will need to fill in the form, then your doctor will sign it and send it off.
Are there similar medicines to valproic acid?
Sodium valproate and semisodium valproate are very similar to valproic acid. They work in the same way but these medicines are sometimes given at different doses for different conditions.
If you decide to try sodium valproate or semisodium valproate instead, your doctor will explain how to come off valproic acid safely.
How does valproic acid compare with other medicines for treating bipolar disorder?
If you have bipolar disorder, there are several types of medicine to prevent mood swings and treat mania. It's not possible to say that one works better than another and it varies from person to person.
Lithium is commonly used for bipolar disorder, as well as anti-epileptic medicines like valproic acid and antipsychotic medicines like olanzapine. You can take valproic acid instead of lithium, or together with lithium, depending on what your doctor recommends.
Your doctor or specialist will find the medicines that work best for you. It depends on your mood swings, how often they happen, how severe they are and how well you cope with a medicine.
How does it compare with other medicines for migraine?
For many people topiramate, propranolol and amitriptyline work better than valproic acid at preventing migraines. These medicines are likely to cause fewer side effects, so your doctor or specialist will usually prescribe one of these first.
Valproic acid is not used as often for preventing migraine. However your doctor may recommend it if these other medicines are causing side effects or are not working for you.
Your doctor may also prescribe valproic acid if you have a health problem that means you cannot take other migraine medicines.
How does it compare with other medicines for epilepsy?
There are many different medicines for treating epilepsy. It's not possible to say that one works better than the others. It varies from person to person and depends on the type of seizures and how often you have them.
Before prescribing a medicine, your doctor will also take into account your age and sex, the medicines you're already taking and any other health problems you have.
It's usual to try to treat epilepsy using a single medicine. If this medicine is not working well, or you're getting side effects, your doctor will try you on a different one.
If a single medicine is not preventing your seizures, then your doctor may recommend taking 2 or more anti-epileptic medicines at the same time.
If valproic acid is giving you side effects, or you're worried it's not suitable for you, ask your doctor or specialist to recommend a different medicine.
Other anti-epileptic medicines include:
What will happen when I come off it?
Do not stop taking valproic acid suddenly, unless your doctor tells you to.
You're unlikely to get any extra symptoms when you stop taking this medicine. However if you're taking it for bipolar disorder or to prevent migraine, your condition could get worse for a short time after you stop taking the medicine.
If you're taking valproic acid for epilepsy, it's possible that you'll get seizures again once you stop taking it. You can prevent these withdrawal seizures by reducing your dose of valproic acid gradually.
Will recreational drugs affect it?
Valproic acid can affect recreational drugs like cannabis and heroin.
If you use recreational drugs alongside valproic acid, you may be more likely to have side effects like panic attacks, anxiety and memory loss.
Can I drink alcohol with it?
Drinking alcohol while taking valproic acid may make you feel sleepy or tired. It's best to stop drinking alcohol during the first few days, until you see how the medicine affects you.
Will it affect my fertility?
Valproic acid can reduce fertility in both men and women. Once you stop taking this medicine, your fertility will return.
In men valproic acid has been reported to cause infertility. However, this is rare.
In women it can change your menstrual cycle, causing delayed or missed periods. Valproic acid has also been reported to cause polycystic ovary syndrome (PCOS), though this happens rarely.
Talk to your doctor if you're concerned about how valproic acid may affect your fertility.
Valproic acid is not recommended if there's a chance you could become pregnant. If you're taking valproic acid and want to start a family, it's important to talk to your doctor as soon as possible. This is because taking valproic acid while pregnant can harm your baby.
Will it affect my contraception?
Valproic acid does not affect any type of contraception, including the combined pill and emergency contraception.
If there's a chance you could become pregnant while taking sodium valproate you must use contraception. Your doctor will put you on Prevent, the valproate pregnancy prevention programme.
Speak to a pharmacist or your doctor if you have any questions about this programme.
Can I drive or ride a bike?
You may feel sleepy, tired or dizzy when you first start taking valproic acid. This may also happen if your dose has increased. If you're affected, do not drive or ride a bike until you feel more alert.
If you have epilepsy, you're not allowed to drive until you've had no seizures for 1 year (or only have seizures while you're asleep).
If you change your epilepsy medicine, your doctor will tell you whether you need to stop driving and for how long.