Lamotrigine

What it is

Lamotrigine is an anticonvulsant that stabilises voltage-gated sodium channels in nerve cells and reduces the release of excitatory neurotransmitters. It is prescription-only and is used for epilepsy and for the depressive side of mood disorders. Its effect is preventive: it reduces how often seizures or mood episodes occur rather than treating an episode in progress.

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

• Epilepsy
• Depression

Approved uses differ by country — some of these may be off-label or unapproved where you live.

What to know while taking it

Food does not matter, but consistency does. The dose is raised slowly on purpose, because a fast increase is what drives the serious skin reactions this drug is known for, and the same slow build-up has to be repeated after any long gap in treatment. Valproic acid slows lamotrigine's breakdown and pushes its level up, while combined pills containing ethinylestradiol and a progestin speed its clearance and can drop the level, with a rebound when they are stopped; liver enzymes such as ALT are sometimes checked alongside. Stopping abruptly can provoke seizures.

When to see a doctor

Any rash, however mild it looks, means stopping the drug and calling a doctor the same day, especially with fever, blistering, mouth or eye involvement or swelling. New or worsening seizures, or a change in another prescription such as a contraceptive, also warrant a doctor's review.

Worth knowing

• Any rash means stop and call a doctor
• The dose must be raised slowly
• Do not stop abruptly

Markers to watch

• ALT