Patients taking etanercept who also have multiple sclerosis are being advised to consult their doctor. Wyeth, the manufacturer of etanercept (Enbrel), has written to pharmacists to say that there have been post-marketing reports of central nervous system (CNS) demyelinating disorders associated with etanercept treatment. However, a causal relationship between etanercept and CNS demyelinating disorders has not been established. The company adds that while there are no trials of etanercept in patients with multiple sclerosis, trials of other TNF (tumour necrosis factor) antagonists have shown an increase in disease activity in patients with the disease. Wyeth recommends that a careful risk/benefit evaluation should be carried out when prescribing etanercept to patients with pre-existing or recent onset of CNS demyelinating disease. A change will be made to the product’s summary of product characteristics following regulatory authority approval.