About lamotrigine

Lamotrigine is a medicine used to treat epilepsy.

It can also help prevent low mood (depression) in adults with bipolar disorder.

Lamotrigine is available on prescription. It comes either as tablets you swallow or tablets you chew or dissolve in water to make a drink.

Key facts

  • It's usual to take lamotrigine once or twice a day. You can take it with or without food.
  • The most common side effects of lamotrigine are skin rashes and headaches.
  • It can take up to 6 weeks for lamotrigine to work. You may still have fits or seizures or feel low during this time.
  • Do not stop taking lamotrigine without talking to your doctor first.
  • If you have epilepsy, you're entitled to free prescriptions for all of your medicines, not just your epilepsy ones.

Who can and cannot take lamotrigine

Lamotrigine can be taken by adults, and by children aged 2 years and over.

Lamotrigine is not suitable for some people.

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

  • have ever had an allergic reaction to lamotrigine or other medicines in the past
  • have liver or kidney problems
  • have bipolar disorder and have ever had thoughts of harming or killing yourself
  • have ever had meningitis or a rash caused by lamotrigine
  • are pregnant or trying to get pregnant
  • have an intolerance to or cannot digest lactose (lactose intolerance) – some brands of lamotrigine contain lactose

How and when to take lamotrigine

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


For epilepsy, the usual dose for:

  • adults and older children (aged 12 years and over) is 100mg to 700mg a day, taken as 1 or 2 doses
  • younger children (aged 2 to 11 years) – the dose will vary depending on their weight

For bipolar disorder, the usual dose for adults is:

  • between 200mg and 400mg a day, taken as either 1 or 2 doses

How to take it

It's usual to take lamotrigine once or twice a day. You can take it with or without food.

If you take it twice a day, try to space your doses evenly through the day. For example, first thing in the morning and in the evening.

Non-chewable or non-dispersible tablets – swallow whole with a glass of water. Do not chew them.

Chewable or dispersible tablets – can be swallowed whole with a glass of water, chewed or mixed with water or juice to make a drink.

Will my dose go up or down?

When you start taking lamotrigine, it's important to increase the dose slowly as this will help reduce or stop some side effects happening.

Once you find a dose that suits you, it'll usually stay the same.

How long will I take it for?

If you have epilepsy, it's likely that once your condition is under control you'll still need to take lamotrigine for many years.

If you have bipolar disorder, it's likely that you'll take lamotrigine for at least 6 months, but possibly much longer.


Do not stop lamotrigine without speaking to your doctor first.

What if I forget to take it?

If you take lamotrigine and you forget a dose:

  • once a day – take the missed dose as soon as you remember. If it's less than 12 hours until your next dose is due, leave out the missed dose and take your next dose as normal.
  • twice a day – take the missed dose as soon as you remember. If it's less than 8 hours before the next dose is due, it's better to leave out the missed dose and take your next dose as normal.

Do not 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 may trigger a seizure.

If you forget to take your tablets for more than 5 days in a row, speak to your doctor, as you'll need to start on a low dose again and gradually increase to your usual dose.

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 lamotrigine can cause serious side effects.

Call your local emergency service if:

You take too much lamotrigine and:

  • have rapid, uncontrollable eye movements
  • feel clumsy or lose your balance
  • feel a change in the rhythm of your heartbeat
  • have had a fit or seizure
  • pass out

Do not drive yourself. Get someone else to drive you or call for an ambulance.

If you need to go to hospital, take the lamotrigine packet or the leaflet inside it, plus any remaining medicine, with you.

Side effects

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

Skin rashes

It's common to get a skin rash with lamotrigine. Most skin rashes are not serious.

But if you develop a skin rash or redness, tell a doctor straight away, as this can develop into a life-threatening skin condition called Stevens-Johnson syndrome.

Stevens-Johnson syndrome is a rare side effect of lamotrigine. It causes flu-like symptoms, followed by a red or purple rash that spreads and forms blisters. The affected skin eventually dies and peels off.

It's more likely to happen in the first 8 weeks of starting lamotrigine, or when the dose is increased too quickly.

It can also happen if lamotrigine is stopped suddenly for a few days and then restarted at the same dose as before, without reducing the dose and then increasing it slowly again.

Stevens-Johnson syndrome is more common in:

  • children
  • people who developed a rash with a different epilepsy medicine in the past
  • people who are allergic to an antibiotic called trimethoprim
  • people also taking a medicine called sodium valproate

To help prevent the chance of you getting a rash that could be confused with Stevens-Johnson syndrome, it's best to not start any new medicines, foods or products during the first 3 months of treatment with lamotrigine.

It's also best to not start lamotrigine within 2 weeks of a viral infection, vaccination or rash caused by something else.

Other 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:

  • headaches
  • feeling drowsy, sleepy or dizzy
  • aggression, or feeling irritable or agitated
  • shaking or tremors
  • difficulty sleeping
  • diarrhoea
  • feeling or being sick (nausea or vomiting)

Other serious side effects

Very few people taking lamotrigine have serious problems.

Tell a doctor straight away if you have a serious side effect, including:

  • thoughts of harming or killing yourself – a small number of people taking lamotrigine for bipolar disorder have had suicidal thoughts, and this can happen after only a few weeks of treatment
  • worsening seizures (if you take lamotrigine for epilepsy)
  • unexpected bruising or bleeding, a high temperature or sore throat – these could be warning signs of a blood disorder
  • a stiff neck, headaches, feeling or being sick, a high temperature and extreme sensitivity to bright light – these could be signs of meningitis

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to lamotrigine.

These are not all the side effects of lamotrigine. For a full list, see the leaflet inside your medicines packet.

How to cope with side effects of lamotrigine

What to do about:

  • 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.
  • feeling drowsy, sleepy or dizzy as your body gets used to lamotrigine, these side effects should wear off. Do not drive, ride a bike or operate machinery until you feel more alert. If they do not go within a week or two, your doctor may reduce your dose or increase it more slowly. If that does not work, speak to your doctor. You may need to switch to a different medicine.
  • aggression, or feeling irritable or agitated –talk to your doctor.
  • shaking or tremors – 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.
  • difficulty sleeping – talk to your doctor.
  • diarrhoea – drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include 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. Speak to a doctor if symptoms get worse or last longer than a week.
  • feeling or being sick - stick to simple meals and do not eat rich or spicy food. It might help to take your lamotrigine after a meal or snack. If you're being sick, take small, frequent sips of water or squash to avoid dehydration. Speak to a doctor if symptoms get worse or last longer than a week.

Pregnancy and breastfeeding

Lamotrigine and pregnancy

There's no firm evidence that lamotrigine is harmful to an unborn baby.

But for safety, your doctor will only advise you to take it in pregnancy if the benefits of the medicine outweigh the risks.

It's important for you and your baby to stay well during pregnancy.

If you become pregnant while taking lamotrigine, tell your doctor or nurse straight away. Do not stop taking it without talking to your doctor first.

If you have epilepsy, it's very important that it's treated during pregnancy as seizures can harm you and your unborn baby.

If you're pregnant, or trying to get pregnant, and taking lamotrigine, you're recommended to take a higher dose of folic acid, a vitamin that helps your baby grow normally.

Your doctor might prescribe a high dose of 5mg a day while you're trying to get pregnant and during the first 12 weeks of pregnancy.

Lamotrigine and breastfeeding

If your doctor or health visitor says your baby is healthy, lamotrigine can be taken while you're breastfeeding.

It's important to keep taking lamotrigine to keep you well. Do not stop taking it without talking to your doctor. Breastfeeding will also benefit both you and your baby.

If you notice your baby is not feeding as well as usual, seems unusually sleepy, or you have any other concerns about them, talk to your pharmacist, health visitor or doctor as soon as possible.

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

Cautions with other medicines

Some medicines and lamotrigine interfere with each other and increase the chances of side effects. Your doctor may need to change your dose of lamotrigine.

Check with your pharmacist or doctor if you're taking:

Mixing lamotrigine with herbal remedies and supplements

There might be a problem taking some herbal remedies and supplements alongside lamotrigine, especially ones that can cause rashes, sleepiness or shaking and tremors.

Ask your pharmacist for advice.

Common questions about lamotrigine