When do you start to feel the onset of cfs?

CFS onset: Cfs affects more women than men (or may be under reported in men), and is most common between the ages of 30 and 60. Symptoms can begin in people younger than 30 too. Cfs is not well understood and difficult to diagnose since there are no specific tests for it. A complete medical work up and inventory of symptoms is needed for diagnosis. I hope this answers your question!