9. Unexplained Fever or Night Sweats
Night sweats and fevers that happen for no clear reason can be early signs of blood cancers such as leukemia or lymphoma, sometimes appearing before anything else.
Night sweats, persistent fevers, and unexplained weight loss are three of the most common symptoms of lymphoma. For these to be considered possible signs of blood cancer, each must meet specific criteria: night sweats must be drenching, requiring a change of nightclothes at least once before morning; weight loss must reflect 10% or more of body weight; and fever must be persistent, higher than 100.4 degrees Fahrenheit, and not due to an underlying infection. When this cluster of three symptoms appears together, medical evaluation is urgent.