Concern over a drug to treat multiple sclerosis leads to a new warning for patients.
The Food and Drug Administration is asking the makers of Avonex to add a stronger warning label to their bottles. The new label will alert patients to an increased risk of liver failure and will recommend that patients be monitored for kidney problems as well.
Avonex, made by Biogen, is the top selling medicine for the treatment of MS. The new warning will match one already attached to another MS drug called "Rebif".