What are the side effects of Lamictal (lamotrigine)?

Lamotrigine (Lamictal) Side Effects

The most serious side effect of lamotrigine is skin rash, which occurs in approximately 5% of patients and can progress to Stevens-Johnson syndrome (0.1% incidence) in rare cases, requiring immediate medical attention. 1

Common Side Effects

Lamotrigine is associated with several common side effects:

• Neurological effects:

  • Headache (most frequently reported)
  • Dizziness (especially during dose titration)
  • Drowsiness/somnolence
  • Ataxia (loss of coordination)
  • Diplopia (double vision)
  • Tremor (less common)

• Gastrointestinal effects:

  • Nausea
  • Vomiting
  • Diarrhea

• Other effects:

  • Insomnia
  • Blurred vision
  • Fatigue 1, 2

Serious Adverse Effects

Dermatological Reactions

• Skin rash - Occurs in ~5% of patients
• Stevens-Johnson syndrome - Rare but serious (0.1% incidence)
• Risk factors for serious rash:
  • Rapid dose escalation
  • Concurrent valproic acid use
  • History of drug allergy
  • Young age 1

Psychiatric Side Effects

Lamotrigine can occasionally cause psychiatric symptoms, including:

• Mood switches
• Psychotic episodes
• Hallucinations 3

Advantages Compared to Other Medications

Unlike many other mood stabilizers and antiepileptics, lamotrigine:

• Does not appear to cause weight gain
• Has fewer cognitive side effects
• Causes less drowsiness than carbamazepine or phenytoin
• Has lower incidence of diarrhea and tremor compared to lithium
• Generally does not require serum level monitoring 4, 5, 2

Risk Reduction Strategies

1. Slow titration schedule:

   • Start with low dose (typically 25mg daily)
   • Gradually increase over 6-8 weeks to target dose
   • This significantly reduces risk of serious rash 1

2. Dose adjustments with concomitant medications:

   • Lower lamotrigine doses when used with valproic acid (inhibits lamotrigine metabolism)
   • Higher doses may be needed with enzyme-inducing antiepileptics (carbamazepine, phenytoin, phenobarbital)
   • Avoid strong inducers of cytochrome P450 when possible 1

3. Monitoring:

   • Baseline complete blood count (CBC) and liver function tests (LFTs)
   • Periodic monitoring throughout treatment
   • More frequent monitoring when adding/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

Dosing Considerations

• Bipolar disorder: Maximum 400mg/day
• Epilepsy: Maximum 600mg/day
• Typical maintenance: 100-200mg/day in 1-2 divided doses 1

Lamotrigine is generally well-tolerated compared to many other mood stabilizers and antiepileptic medications, with the primary concern being vigilance for skin rash, particularly during the initial titration period.