A client starting lamotrigine for bipolar disorder calls the clinic on day 18 reporting a new diffuse maculopapular rash on the chest and arms with mild oral mucosal soreness. Which is the nurse's priority action?
1Take diphenhydramine and reassess in 48 hours
2Reassure that mild rash is common and ask her to keep taking the medication
3Instruct her to STOP lamotrigine immediately and go to the ED — any rash on lamotrigine requires urgent evaluation for Stevens-Johnson syndrome✓ Correct answer
4Apply hydrocortisone cream and continue therapy
Explanation
Correct (2): Lamotrigine carries a boxed warning for Stevens-Johnson syndrome (SJS) and TEN; risk is highest in the first 8 weeks, especially with rapid titration or coadministered valproate. ANY rash on lamotrigine must be considered SJS until proven otherwise — stop the drug, urgent ED evaluation. Mucosal involvement is especially ominous. (1,3,4) Delay risks progression to TEN with high mortality.
In-depth explanation
Memory Tip Lamotrigine = "Lamo-Slow" titration mandatory. Rash + Lamotrigine = STOP + ED. CPG Slow titration (25 mg → 25 mg → 50 mg over weeks) reduces but does NOT eliminate SJS risk.
Clinical scenario
Scenario 35-year-old female on lamotrigine per standard slow-titration schedule × 18 days for bipolar I disorder. Now reports new diffuse rash on chest/arms with mouth soreness.
Key concepts
Lamotrigine titration — Mandatory slow dose escalation schedule (weeks) to reduce SJS risk; rapid titration is contraindicated.
Stevens-Johnson syndrome — Severe mucocutaneous reaction with epidermal detachment; can progress to TEN with high mortality.
Drug-induced rash — Any rash on lamotrigine warrants immediate discontinuation and emergency evaluation.