Lamotrigine (Lamictal): Side Effects to Discuss With Your Prescriber

Lamotrigine, commonly prescribed under the brand name Lamictal (amongst other brand names), is one of the most widely used anti-seizure medications (ASMs) in the UK. It is often chosen because many people tolerate it well, but like any ASM it can cause side effects, and there are a small number of serious reactions that everyone taking it should be able to recognise. This guide explains what to look out for and when to speak to a prescriber. It is general information and does not replace advice from a doctor, pharmacist or epilepsy specialist.

What lamotrigine is used for

Lamotrigine is prescribed to help control several seizure types, including focal seizures and generalised seizures such as tonic-clonic seizures. It is also used as a mood stabiliser in bipolar disorder. It is usually started at a low dose and increased slowly over several weeks, which is an important safety step rather than an inconvenience.

How lamotrigine works

Lamotrigine acts on the electrical activity of the brain, calming the excessive signalling that can lead to a seizure. It does this partly by stabilising the sodium channels in nerve cells. Understanding this helps explain why the dose is built up gradually and why it should never be stopped abruptly.

Common side effects

Most side effects are mild and often settle as the body adjusts. They include:

• Headache
• Feeling or being sick (nausea or vomiting)
• Dizziness or drowsiness
• Tiredness and difficulty sleeping
• Dry mouth and diarrhoea
• Shaking or tremor
• Feeling agitated, irritable or restless
• Blurred or double vision

If any of these are persistent or troubling, a prescriber or pharmacist can advise. People should not reduce or stop the medication on their own.

Serious side effects to act on

Skin rash

The most important reaction to know about is a skin rash. In rare cases lamotrigine can cause a severe reaction such as Stevens-Johnson syndrome, a serious illness that begins with flu-like symptoms and a spreading, blistering rash. The risk is higher when the dose is increased too quickly, when lamotrigine is taken alongside sodium valproate, and in children. Most rashes appear in the first eight weeks of treatment.

Anyone who develops a new rash, blistering, peeling skin, or sores in the mouth, eyes or genitals should seek urgent medical advice straight away.

Please note: The rash can occur even for users that are well established on the medication.

Other serious reactions

Seek prompt medical help for signs of an allergic reaction (a swollen face, throat or tongue, or difficulty breathing), signs of liver problems (yellowing of the skin or eyes, severe tiredness), or signs of a blood problem (unexplained bruising or bleeding, repeated infections or a high temperature).

Heart rhythm

Lamotrigine is not recommended for people with Brugada syndrome, an inherited heart-rhythm disorder. Regulators have also examined a possible risk for people who already have structural or ischaemic heart disease. Anyone with a known heart condition should make sure their prescriber is aware before starting lamotrigine.

Mood and mental health

As with other ASMs, a small number of people may experience low mood or thoughts of self-harm. Any such thoughts should be treated seriously and raised with a healthcare professional without delay.

Contraception and pregnancy

Hormonal contraception can lower the level of lamotrigine in the body, and starting or stopping the combined pill can change how well seizures are controlled. Anyone considering a change to their contraception, or planning a pregnancy, should discuss it with their epilepsy team first so the dose can be reviewed.

Do not stop suddenly

Stopping lamotrigine abruptly can trigger seizures. Any change to the dose should be planned and supervised by the prescribing team.

A note for carers and support staff

Those supporting someone taking lamotrigine should know the person’s usual routine, be alert to any new skin rash in the early weeks of a dose change, and know who to contact. This awareness sits alongside, and does not replace, the person’s individual support plan.

This article is general education and does not replace advice from a prescriber or epilepsy specialist. Never change or stop an ASM without medical advice.