What causes body aches?

A number of. situations including overuse, tenseness, blunt injury to a muscle group, certain febrile illnesses releasing toxins that cause muscle aching, or simply the rigors associated with recurrent high fevers. Autoimmune diseases such as myositis, polymyalgia rheumatica and some of the connective tissue diseases such as Ehlers-Danlos. By far the most common is overuse of muscle groups with activity.