What are the common side effects of lamotrigine?

Common Side Effects of Lamotrigine

The most common side effects of lamotrigine include headache, dizziness, drowsiness, nausea, and skin rash, with rash being the most serious potential adverse effect requiring immediate medical attention. 1

Common Neurological Side Effects

• Headache: Frequently reported in clinical trials
• Dizziness: Common, especially during dose titration; may affect driving ability initially
• Drowsiness/Somnolence: May impact daily activities
• Ataxia (loss of coordination): Can occur during initial treatment, particularly with higher doses or rapid titration
• Diplopia (double vision): More common during initiation or dose increases
• Tremor: Less common but reported in some patients 1

Gastrointestinal Side Effects

• Nausea: Commonly reported during initiation
• Vomiting: Less common but may occur
• Abdominal pain: More frequent in polytherapy than monotherapy 2

Dermatological Side Effects

Skin rash is the most significant concern with lamotrigine therapy:

• Incidence of allergic skin reactions: Approximately 5% of patients 1, 3
• Stevens-Johnson syndrome: Rare but serious complication (0.1-0.4% incidence) 1, 3
• Risk factors for rash development:
  • Rapid dose escalation
  • Concurrent valproic acid use
  • History of drug allergy
  • Young age 1

Most skin rashes appear during the initiation phase, typically within the first 8 weeks of treatment 3. While most rashes are mild, any rash should be evaluated immediately due to the risk of progression to more serious conditions.

Side Effects by Treatment Regimen

Children and adults on lamotrigine polytherapy experience significantly higher rates of:

• Headache
• Somnolence
• Nausea
• Vomiting
• Dizziness
• Abdominal pain 2

Serious but Rare Side Effects

• Stevens-Johnson syndrome: Life-threatening mucocutaneous disease characterized by flat, diffuse erythematous maculopapular rashes 4
• Blood disorders: Unexplained bruising or bleeding (rare)
• Liver abnormalities: Jaundice (rare) 1

Monitoring Recommendations

1. Baseline testing: Complete blood count (CBC) and liver function tests (LFTs) before initiation
2. Periodic monitoring: Throughout treatment, especially after dose adjustments
3. More frequent monitoring: When adding or removing medications that affect lamotrigine metabolism 1

Patient Education

Patients should seek immediate medical attention if they experience:

• Any skin rash, regardless of severity
• Unexplained bruising or bleeding
• Signs of infection
• Jaundice
• Symptoms of lamotrigine toxicity (severe dizziness, ataxia, diplopia, blurred vision, nausea, vomiting) 1

Lamotrigine has an overall acceptable safety profile compared to many other antiepileptic drugs, with relatively low rates of treatment discontinuation due to adverse effects (approximately 1.9% in pediatric studies) 2, 5.