It has been suggested that cyclosporin A might be of some benefit to patients 
with Crohn's disease. The clinical response and side-effects of cyclosporin A in 
Crohn's disease are described in a series of 13 adults. The majority of patients 
had ileal disease and all but one were started on an initial oral dose of 15 
mg/kg per day. Duration of treatment ranged from 3 to 42 weeks. Of the 13 
patients, 6 showed a response to therapy; the remainder showed no response or 
deteriorated. The commonest side-effect was hyperaesthesia, but one patient 
developed nephrotoxicity and one developed hepatotoxicity. Significant drug 
malabsorption occurred in one case. The side-effects were dose dependent and 
reversible. Cyclosporin A may have a part to play in the treatment of resistant 
Crohn's disease, and in our hands has been associated with a 46 per cent 
response rate; however, the precise role of cyclosporin A in the management of 
Crohn's disease awaits further study.