Antiepileptic Drug (AED) Pregnancy: Large data (>12,700 pregnancies) do not indicate an increased risk of major congenital malformations at maintenance doses; use the lowest effective dose. Folic acid supplementation advised; monitor serum levels around pregnancy. Do not stop AED therapy abruptly.

Lamotrigine

Brand names: Lamictal

Lamotrigine is an antiepileptic drug used in children for focal and generalised seizures (including Lennox-Gastaut syndrome) and as an alternative when other agents are unsuitable. This page covers its use in the paediatric population.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 100-200 mg/day (usual maintenance, monotherapy, aged 13 years and above)

Route: Oral (tablets swallowed whole; may be halved but not chewed/crushed)

Frequency: Once daily or in two divided doses (maintenance)

Epilepsy. This record captures paediatric dosing in paedDose. Adults and adolescents aged 13 years and above follow the Table 1 regimens (monotherapy 25 mg/day weeks 1-2, 50 mg/day weeks 3-4, maintenance 100-200 mg/day). Because of rash risk the initial dose and escalation must not be exceeded. If the calculated paediatric dose does not equate to whole tablets, give the dose equal to the lower number of whole tablets. Not recommended below 2 years of age.

Paediatric dose

Route: Oral

Frequency: Once daily or in two divided doses

Max: 200 mg/day (monotherapy of typical absence seizures, or adjunctive WITH valproate); 400 mg/day (adjunctive WITHOUT valproate but WITH glucuronidation inducers)

Children and adolescents aged 2-12 years, total daily dose by body weight; initial dose and escalation must not be exceeded (rash risk). Monotherapy of typical absence seizures: 0.3 mg/kg/day (weeks 1-2), 0.6 mg/kg/day (weeks 3-4), then maintenance 1-15 mg/kg/day (increase by max 0.6 mg/kg/day every 1-2 weeks; max 200 mg/day). Adjunctive WITH valproate: 0.15 mg/kg/day (weeks 1-2), 0.3 mg/kg/day (weeks 3-4), maintenance 1-5 mg/kg/day (increase by max 0.3 mg/kg/day; max 200 mg/day). Adjunctive WITHOUT valproate but WITH inducers (phenytoin, carbamazepine, phenobarbitone, primidone, rifampicin, lopinavir/ritonavir): 0.6 mg/kg/day (weeks 1-2), 1.2 mg/kg/day (weeks 3-4), maintenance 5-15 mg/kg/day (increase by max 1.2 mg/kg/day; max 400 mg/day). If the calculated dose is not a whole tablet, round down to the lower whole tablet. Safety/efficacy below 2 years not established. Verify against a current children's formulary.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to lamotrigine, sunset yellow aluminium lake, or any of the excipients

Side effects

Skin rash (very common) — risk of serious rash (SJS/TEN/DRESS) is higher in children than adults; rash with fever in the first 8 weeks may be mistaken for infection
Headache (very common)
Somnolence, dizziness, tremor, insomnia (common)
Nausea, vomiting, diarrhoea (common)
Aggression, irritability (common)

Interactions

Valproate — inhibits lamotrigine glucuronidation and raises lamotrigine levels; use the lower valproate-specific titration and maintenance dosing
Enzyme-inducing drugs — phenytoin, carbamazepine, phenobarbitone, primidone, rifampicin, lopinavir/ritonavir induce glucuronidation and lower lamotrigine levels; use the higher inducer-specific titration

Clinical monograph

How it works

It stabilises neuronal membranes by inhibiting voltage-gated sodium channels, reducing the release of excitatory neurotransmitters such as glutamate.

Prescribing in practice

The most important paediatric concern is the risk of serious, potentially life-threatening skin reactions (including Stevens-Johnson syndrome and toxic epidermal necrolysis), which is higher in children and is strongly linked to rapid dose escalation and concomitant valproate, so titration must be slow and any rash assessed urgently.
Initial doses and titration schedules differ substantially depending on whether the child also takes valproate (which raises lamotrigine levels) or enzyme-inducing antiepileptics; always confirm against a children's formulary.
Withdrawal should be gradual to avoid rebound seizures, and parents should not stop the drug abruptly.

Monitoring

Monitor for rash and hypersensitivity (especially in the first weeks), seizure control and behavioural changes; routine plasma-level monitoring is not generally required but may help in specific situations.

Counselling the patient

Seek urgent medical advice for any rash, mouth ulcers, fever, blistering or facial swelling, particularly in the first eight weeks.
Do not stop the medicine suddenly, and give it at the same times each day.
Tell the prescriber about any change in other medicines, as this can affect lamotrigine levels.

Evidence & guidelines

MHRA guidance highlights the dose-related risk of serious skin reactions with lamotrigine, and its paediatric use is supported by NICE epilepsy guidance.

Reference: NICE NG217 (Epilepsy); MHRA Drug Safety Update (lamotrigine rash); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways