Medical School researchers have identified a promising drug that may prove useful in relieving chronic fatigue syndrome.

Associate Prof. Jose Montoya and postdoctoral student Andreas Kogelnik have seen 21 of the 25 patients they have treated over the past three years with drug valganciclovir improve significantly. Even better, the improvement has been sustained after patients cycled off the drug, an antiviral often used in treating diseases like herpes.

“This study is small and preliminary, but potentially very important,” said Anthony Komaroff, a Harvard Medical School Professor. “If a randomized trial confirmed the value of this therapy for patients like the ones studied here, it would be an important landmark in the treatment of this illness.”

Roche Pharmaceutical has granted Montoya $1.3 million to continue research into the drug starting this quarter. Chronic fatigue syndrome affects one million people worldwide.