Medication guide

Lamotrigine (Lamictal)

What is lamotrigine?

Lamotrigine is known as Lamictal in the United States, the UK, and Japan alike (ラミクタール on Japanese packaging). It's a mood stabiliser that is also an epilepsy medicine: it steadies overexcitable brain signalling, and in bipolar disorder its approved job is keeping mood episodes from coming back.

How is it different from other mood medicines?

Built for prevention: in bipolar disorder its role is keeping episodes from returning, not treating one that is already under way
Large pregnancy registries: they have not shown a substantial rise in major malformations
Light to live with for most people: it is not sedating for most, and weight gain is not among its listed side effects
A very short rule-out list: a single formal contraindication

What is it used for in Japan?

Preventing the return of mood episodes in bipolar disorder
Several types of epilepsy

How does it help?

By steadying overexcitable signalling, it makes the next mood episode less likely; it prevents episodes rather than treating one that has started. Because of that, the benefit shows over months of stability rather than days, and it is built up slowly on purpose (see below).

What should I tell my doctor before starting?

Only one situation rules it out entirely:

A past allergic reaction to lamotrigine

And tell your doctor first if any of these apply; these usually just need adjustments or a closer eye:

Valproate (Depakene), or epilepsy medicines like carbamazepine or phenytoin; these change lamotrigine's level, and the build-up schedule is adjusted around them
The contraceptive pill: it lowers lamotrigine's level, so starting or stopping it means the dose is checked
A rash or allergic reaction with another epilepsy medicine in the past
Heart disease or a heart rhythm problem
Kidney or liver problems
Pregnant, planning to be, or breastfeeding (see the section below)

How do I take it, and what if I miss a dose?

Lamotrigine is taken once or twice a day, and it is built up slowly, week by week, on a fixed schedule. Going up faster than the schedule raises the risk of the rash described below, so the schedule is the safety system. Don't speed it up, even if you feel nothing yet.

If you miss a dose: take it when you remember, unless the next dose is close; in that case just skip. Never take a double dose to catch up
If you've missed several days in a row: don't just restart at your usual dose; call us first. After a break, the slow build-up may need to start again

What side effects should I expect?

Most are mild and settle as your body adjusts, and many can be eased with a counter-medicine if they persist. Not everyone gets them; the rough figures below, from the Japanese study in bipolar disorder, just give a sense of how common each one is.

Rash (under 10%): most rashes on lamotrigine are harmless, but with this medicine, every rash gets checked (see below)
Headache (under 5%)
Nausea or stomach upset (under 5%)
Drowsiness (under 5%)
Dizziness
Double or blurred vision, in some people

If anything is bothering you, tell your doctor; there's often a way to adjust.

Finally, the one thing everyone starting lamotrigine should know:

Rarely, lamotrigine can cause a serious skin reaction, and the slow build-up schedule exists to lower that risk. The rule is simple: a new rash, or any of fever, sore throat, mouth sores, red eyes, unusual tiredness, or swollen glands, especially in the first eight weeks, means contact us straight away. If a rash comes with any of those other signs, don't take the next dose until we've spoken. The serious forms are rare, and less likely still when the schedule is followed

Will I become dependent? How do I stop safely?

No; lamotrigine isn't habit-forming. Stopping is about protection rather than withdrawal: coming off removes its protection against the next episode, so the decision and the pace are planned with your doctor, usually stepping down gradually.

Can I drive while taking it?

For bipolar disorder, the Japanese label advises against driving while taking it. Lamotrigine can cause drowsiness or dizziness in some people, and for the bipolar indication the prescribing information here instructs that patients on it shouldn't drive or operate dangerous machinery. Discuss your own situation with your doctor.

What about pregnancy and breastfeeding?

If lamotrigine is working well without troublesome side effects, Japan's bipolar guideline suggests continuing it in pregnancy. Large international registries have not shown a substantial rise in major malformations, though some studies, not all, have reported a higher rate of cleft lip or palate. The Japanese label allows it in pregnancy when the benefit is judged to outweigh the risk, and blood levels can fall during pregnancy, so doses are watched. Never stop on your own on learning you're pregnant.

Breastfeeding is the more cautious conversation with this particular medicine: a relatively large amount passes into milk (an infant's level can reach up to about half of the mother's), and drowsiness, pauses in breathing, and poor weight gain have been reported in breastfed infants, so the Japanese label says to avoid breastfeeding while taking it; any exception is a carefully monitored, individual decision. Our guides to medication in pregnancy and medication while breastfeeding cover the details.