Hand, foot, and mouth disease (HFMD) spreads through direct contact with an infected person’s saliva, nasal droplets, blister fluid, or stool. Symptoms typically appear 3 to 6 days after exposure and start with a fever and sore throat before progressing to the telltale mouth sores and skin rash. Most cases are mild and resolve within 7 to 10 days.
How the Virus Spreads
HFMD is caused by enteroviruses, most commonly coxsackievirus. These are tough, non-enveloped viruses that spread easily through several routes:
- Respiratory droplets: When a sick person coughs, sneezes, or talks, tiny droplets carrying the virus become airborne and can be inhaled or land on nearby surfaces.
- Direct contact: Kissing, hugging, sharing cups or utensils, or simply touching someone who’s infected can transfer the virus.
- Fecal-oral route: Changing a diaper and then touching your face without washing your hands is one of the most common ways adults catch it from children.
- Blister fluid: The fluid inside HFMD blisters is packed with virus. Touching a popped blister and then touching your own eyes, nose, or mouth can lead to infection.
The virus is remarkably durable on surfaces. Coxsackieviruses can survive on hard surfaces like countertops, doorknobs, and toys for at least two weeks at room temperature. That’s why outbreaks tear through daycares and preschools so quickly. A child touches a contaminated toy, puts their fingers in their mouth, and the cycle continues.
The First Signs: What Happens Before the Rash
The illness doesn’t start with the blisters most people associate with HFMD. It begins 3 to 6 days after exposure with symptoms that look a lot like any other childhood virus: a low fever, sore throat, general fussiness, and a reduced appetite. Children may refuse food or drink because swallowing hurts, even before you can see anything in their mouth. This early stage lasts roughly one to two days before the more recognizable symptoms appear.
Mouth Sores and Skin Rash
A day or two after the fever starts, painful sores develop inside the mouth. They often show up on the tongue, gums, and the inside of the cheeks. These aren’t the same as cold sores on the lips. They’re small, red spots that blister and can become shallow ulcers, making eating and drinking genuinely painful for young children. Dehydration is the most common practical concern during this phase, simply because kids don’t want to swallow anything.
Around the same time or shortly after, a rash appears on the palms of the hands and soles of the feet. It can also show up on the knees, elbows, buttocks, and groin. The spots are flat or slightly raised, red, and sometimes blister. They’re not usually itchy in the way chickenpox is, but they can be tender. The rash typically doesn’t scar, and in most children the whole illness wraps up within 7 to 10 days.
How Symptoms Differ in Adults
Adults absolutely can get HFMD, and many parents catch it from their own children. The same symptoms appear: fever, mouth sores, and rash on the hands and feet. Some adults experience milder symptoms or no symptoms at all, but others report that the mouth pain and rash feel worse than what their child went through. Adults can also spread the virus even with mild or unnoticeable symptoms, which is why it often makes the rounds through an entire household.
One oddity that catches people off guard: some adults and children lose fingernails or toenails a few weeks after the infection clears. The nails typically grow back on their own, but it can take several months.
How Long You’re Contagious
A person with HFMD is most contagious during the first week of illness, especially while they have a fever and open blisters. But the virus can linger in stool for weeks after symptoms disappear, which means careful hand hygiene around diaper changes and bathroom use matters long after a child seems healthy. Respiratory shedding tends to drop off faster, usually within a week or two of symptom onset.
Rare but Serious Complications
The vast majority of HFMD cases resolve without any lasting problems. In rare instances, particularly with a specific strain called enterovirus A71, the infection can affect the central nervous system. This can lead to viral meningitis (inflammation of the membranes around the brain and spinal cord), encephalitis (inflammation of the brain itself), or in very rare cases, temporary paralysis. Warning signs of neurological involvement include persistent high fever, severe headache, stiff neck, unusual drowsiness, or repeated vomiting. These complications are uncommon in typical outbreaks but are the reason a fever lasting more than three days warrants a visit to a healthcare provider.
Prevention and Hygiene
There’s no vaccine for the strains of HFMD common in most countries. Prevention comes down to hygiene, and the details matter more than you might expect. Standard alcohol-based hand sanitizers, the kind most people carry in a bag or keep by the front door, perform poorly against the viruses that cause HFMD. Research on enterovirus 71 found that the typical 70% ethanol in commercial hand sanitizers produced almost no meaningful reduction in virus levels, even after a full 10 minutes of contact. Only 95% ethanol showed strong effectiveness, and that concentration is impractical for everyday use.
Washing hands thoroughly with soap and water is far more effective than relying on sanitizer alone. Scrub for at least 20 seconds, especially after changing diapers, using the bathroom, and before preparing food. Clean frequently touched surfaces like doorknobs, light switches, and toys with a disinfectant that’s effective against non-enveloped viruses (bleach-based cleaners work well). Keep sick children home from daycare until their fever is gone and mouth sores and blisters have healed, and avoid sharing utensils, cups, and towels within the household during an active infection.