1 The majority of HFMD infections are self-limited, so no treatment is required. 2  HFMD, caused by coxsackie viruses, usually causes fever, malaise, rash, and small blisters that ulcerate. 3  The most frequent locations for the blisters /ulcers are on the palms of the hand, soles of the feet, and in the mouth.r. Charles Pat Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston).