Comparison of carbamazepine rash in multiple sclerosis and epilepsy.

Objectives: Studies on the comorbidity of multiple sclerosis (MS) and allergic disorders have shown conflicting results. Carbamazepine (CBZ) is widely used in MS to control pain. We have compared the incidence of rash from CBZ use in MS and epilepsy.
Materials and Methods: Consecutive adult patients with MS and epilepsy were studied retrospectively. A detailed survey of medical records concerning CBZ treatment was performed.
Results: A total of 495 patients with epilepsy and 442 patients with MS were included. Sixty-five per cent of patients with epilepsy and 20% of patients with MS had used CBZ. In CBZ-exposed patients, rash occurred in 15/89 (17%) in MS and in 43/323 (13%) in epilepsy, a difference which was not significant. Women below 50 years experienced more skin reactions than older women and men. The unadjusted odds ratio (OR) for rash in the MS vs epilepsy group was 1.32 (CI 0.70-2.51, P = 0.40). Adjusting groups for gender and age reduced the OR to 1.11 (CI 0.56-2.19, P = 0.76).
Conclusion: Compared with epilepsy, which is only rarely caused by immunological mechanisms, the autoimmune disorder MS was not associated with a different occurrence of CBZ skin reactions. The trend towards an increased occurrence of rashes in MS can partly be explained by a higher predisposition to CBZ rash in women of fertile age.
(© 2011 John Wiley & Sons A/S.)