Lamotrigine

Key facts

• Lamotrigine (sold as Lamictal) is an anticonvulsant and mood stabiliser used for epilepsy and to prevent depressive episodes in bipolar disorder.
• You take it daily, starting at a deliberately low dose that is increased slowly over several weeks; this slow build-up is the main way to reduce rash risk.
• Lamotrigine can cause a serious rash, including Stevens-Johnson syndrome, and this is far more likely if the dose is raised too fast or combined with valproate. Any new rash in the first two months needs urgent medical review.
• Seek urgent care for a spreading or blistering rash, fever with a rash, or swelling of the face or mouth.

What lamotrigine treats

Lamotrigine treats focal and generalised seizures in epilepsy, including seizures linked to Lennox-Gastaut syndrome. It is also used long-term in bipolar disorder to prevent depressive episodes. It is not intended to treat an acute manic episode.

How lamotrigine works

Lamotrigine blocks sodium channels on nerve cells and reduces the release of glutamate, a chemical that excites nerve activity. This slows abnormal electrical firing in the brain, reducing seizures and helping to stabilise mood over time.

Before you take it

• Tell your prescriber if you take valproate: it roughly doubles lamotrigine levels, so your starting dose and titration schedule will be slower and lower.
• Tell your prescriber about any previous rash with an anticonvulsant, and about liver or kidney disease.
• Hormonal contraceptives containing oestrogen can lower lamotrigine levels, and lamotrigine can make some contraceptive pills less reliable; discuss contraception planning with your prescriber.
• Never restart lamotrigine at your previous dose after missing several days or more. Restarting needs the same slow build-up as starting fresh, because rash risk returns.

Side effects

Common effects include headache, dizziness, nausea and mild rash, especially while the dose is being increased.

Stop and seek urgent medical care for any of these:

• Any new or worsening rash, especially with blistering, peeling skin, or mouth sores.
• Fever with a rash, or swollen glands.
• Swelling of the face, lips, tongue or throat, or difficulty breathing.
• Unusual bruising or bleeding.

Safety essentials

• Lamotrigine's rash risk, including rare but life-threatening Stevens-Johnson syndrome, is highest in the first eight weeks and rises sharply if the dose is increased faster than prescribed. Always follow the slow titration schedule exactly and never speed it up.
• Treat any new rash as a medical emergency until a doctor has assessed it, particularly early in treatment.
• Restarting after a gap of several days or more needs the original slow dose build-up, not your previous maintenance dose.
• Do not stop lamotrigine abruptly. Sudden withdrawal can trigger seizures.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.