The principal aim of this study is to determine whether chronic fatigue syndrome (CFS) is due to inadequate blood flow to the brain and to test a medication, Viagra, which should help increase blood flow to the brain and improve the symptoms of CFS. 6 weeks [clinicaltrials_resource:3238519590c79fd987c2fdd3fd289d1d]

Double Blind study- one group will be on Sildenafil (Viagra) and the other group will be on placebo.

The principal aim of this study is to determine whether chronic fatigue syndrome (CFS) is due to inadequate blood flow to the brain and to test a medication, Viagra, which should help increase blood flow to the brain and improve the symptoms of CFS. 6 weeks [clinicaltrials_resource:3238519590c79fd987c2fdd3fd289d1d]

Double Blind study- one group will be on Sildenafil (Viagra) and the other group will be on placebo.