Lamotrigine: uses, rash warning and cautions

Lamotrigine is an anti-seizure medicine that is also used as a mood stabiliser. According to the NHS it can be used for seizures caused by epilepsy and for low mood (depression) in people with bipolar disorder. It is prescription-only, and the NHS gives Lamictal as the UK brand.

In epilepsy, the NHS explains it works by blocking the signals in the brain that can cause seizures. For bipolar depression the NHS says it is not clear how it helps with mood, which is a candid point worth knowing: the medicine has a track record, but the mechanism there is not fully mapped.

Lamotrigine comes as ordinary tablets and dispersible tablets that are dissolved in water before drinking. The NHS says it is taken once or twice a day, with or without food. Tablets are swallowed whole with water, may be broken in half if needed, and should not be chewed or crushed.

The NHS does not set out a fixed dose. The amount depends on age, on any other medicines being taken and on whether there are kidney or liver problems. Clinicians usually start low and raise the dose slowly over weeks, and that slow start is closely linked to the rash risk described below.

Rash appears on the NHS list of common side effects, and most rashes are not dangerous. The difficulty is that a small number are the start of a severe skin reaction, so a new rash is not something to wait out. The NHS describes round, slightly raised patches (erythema multiforme), painful blisters (Stevens-Johnson syndrome) and peeling skin as the serious forms.

Anyone who has previously had a rash on lamotrigine is among those the NHS says should not take it. If you think you may be having a serious reaction, the NHS tells you to call NHS 111, and it lists anaphylaxis, with a swollen throat or tongue or difficulty breathing, as an emergency.

Alongside rash, the NHS lists headaches, nausea and vomiting, dizziness or drowsiness, dry mouth, diarrhoea, tiredness, difficulty sleeping, tremor, and feeling agitated, irritable or aggressive. If you are dizzy or drowsy after a dose, do not drive, ride a bike or use machinery until it passes.

Less common but serious effects include liver problems (tiredness, itchy skin, yellowing of the whites of the eyes) and blood cell problems (breathlessness, tiredness and headache from anaemia, or easier bruising and bleeding). The NHS also tells anyone with thoughts of harming themselves to use NHS 111. The usual advice is to keep taking the medicine through mild effects unless told otherwise, and to report suspected effects through the Yellow Card scheme.

The NHS names sodium valproate, carbamazepine, risperidone, rifampicin and HIV treatments among medicines that can interact with lamotrigine. Sodium valproate in particular is significant because it changes how lamotrigine is handled, which is why prescribers adjust doses when the two are combined.

Hormonal contraceptives such as the combined pill may also interact. The NHS says a doctor may recommend a different type of hormonal contraceptive, or another method such as condoms. Tell the prescriber if you start or stop a hormonal method, since the effect on lamotrigine can change.

Lamotrigine can be used in pregnancy and while breastfeeding, according to the NHS, with the doctor weighing risks against benefits. In pregnancy the lowest effective dose is aimed for and folic acid may be recommended. A breastfed baby may show a rash, drowsiness or poor weight gain, and those signs should be mentioned to a health professional.

Planning ahead with the epilepsy team helps. The wider guide on epilepsy and pregnancy on this site explains why medicine reviews before conception are so common.

The NHS says you can drink alcohol but should avoid heavy drinking, because it may make you sleepy and raise the chance of a seizure. Driving is a separate matter: avoid it when dizzy or drowsy, and remember that epilepsy carries its own legal driving rules.

Keep taking lamotrigine for as long as the doctor advises. When treatment ends the dose is usually reduced gradually under supervision. If you take more than prescribed, the NHS advises using NHS 111 and taking the packet to any appointment.