Hand, Foot, and Mouth Disease (HFMD) is a common viral infection, primarily seen in young children, though adults can also contract it. It is caused by viruses belonging to the Enterovirus group, most often Coxsackievirus A16 or Enterovirus 71. This illness is characterized by a mild fever and a distinctive rash of small, fluid-filled blisters that appear on the hands, feet, and inside the mouth.
The Lifecycle of Hand, Foot, and Mouth Lesions
The lesions associated with HFMD begin as small, non-itchy red spots (macules) that rapidly evolve into slightly raised bumps. Within a day or two, these spots transform into small, oval-shaped blisters filled with clear fluid. The virus typically targets the palms of the hands and the soles of the feet, but the rash can also appear on the buttocks or other areas of the body.
A defining feature of HFMD lesions is that they do not involve the deep layers of the skin. Because of this superficial nature, the blisters usually dry up, flatten, and fade away rather than forming the thick, dark scabs seen with conditions like chickenpox. Traditional scabbing is not the common progression, though some lesions might peel as they resolve.
Lesions that form inside the mouth, referred to as herpangina, appear on the tongue, gums, and inner cheeks. These vesicles are fragile and quickly rupture, creating painful, shallow ulcers. These ulcers are the reason children may refuse to eat or drink, which is the most common concern for dehydration during the illness.
How Long Symptoms Typically Last
The entire course of uncomplicated HFMD is self-limiting, with symptoms resolving within seven to ten days. The illness often begins with a fever, which is one of the first symptoms to disappear, usually within two to three days. Following the fever, the characteristic rash and mouth sores develop and peak in severity.
The painful mouth ulcers begin to heal, and the skin lesions on the hands and feet will also begin to dry and flatten, with the rash fully fading around the seven-to-ten-day mark.
Less common symptoms may appear weeks after the initial infection has passed. About one to two weeks after the rash has cleared, the skin on the palms and soles may begin to peel. A more delayed, though still rare, symptom is onychomadesis, the temporary shedding or loss of fingernails or toenails. This can occur three to six weeks following the illness, and the nails will grow back normally over time.
When Contagion Ends
Hand, Foot, and Mouth Disease is highly contagious, transmitted through contact with respiratory droplets, nasal or throat discharges, and the fluid from the blisters. The period of highest contagiousness is during the first week of the illness, often before the rash has fully appeared.
The blisters are considered infectious until they have completely dried up and the fluid inside is gone. Children are generally cleared to return to school or daycare once their fever has resolved and any open mouth sores have healed.
The virus can continue to shed in the feces for several weeks, sometimes up to two months, even after symptoms clear. Frequent handwashing, especially after using the toilet or changing diapers, remains an effective measure to limit the continued spread of the virus.