Hand, foot, and mouth disease (HFMD) spreads through direct contact with an infected person’s saliva, nasal mucus, blister fluid, or stool. It’s caused by a group of viruses called enteroviruses, most commonly coxsackievirus A16 in the United States. The disease is highly contagious, and you can catch it even from someone who doesn’t look sick.
How the Virus Spreads
There are several specific routes of transmission, and most of them involve ordinary, everyday contact:
- Close personal contact: Kissing, hugging, or sharing cups and utensils with an infected person transfers saliva that carries the virus.
- Respiratory droplets: When someone with HFMD coughs or sneezes, virus-laden droplets enter the air. Breathing these in or getting them on your hands and then touching your face is enough for infection.
- Blister fluid: The small blisters that form on the hands, feet, and mouth contain active virus. Touching a blister, or a surface the fluid has landed on, and then touching your own mouth, nose, or eyes can transmit the infection.
- Fecal-oral route: The virus sheds in stool for weeks after infection. Diaper changes, shared bathrooms, and inadequate handwashing create opportunities for fecal-oral transmission. This is one of the main reasons the virus tears through daycare centers.
- Contaminated surfaces: Touching doorknobs, toys, or countertops that an infected person has handled can pass the virus along.
How Long the Virus Survives on Surfaces
The enteroviruses that cause HFMD lose their ability to infect within a few hours on dry surfaces like plastic, metal, or wood. That sounds reassuring, but a few hours is plenty of time for a child to touch a contaminated toy and then put their fingers in their mouth. Interestingly, while the live virus dies off quickly, traces of viral genetic material can linger on dry surfaces for up to 28 days. That residual material isn’t infectious, but it explains why surface swabs sometimes test positive long after an outbreak has ended.
When Someone Is Most Contagious
A person with HFMD is most contagious during the first week of illness, particularly while blisters are present and oozing. But the tricky part is that the virus also spreads before symptoms appear. There’s an incubation period of roughly three to six days after exposure, during which a person carries and sheds the virus without knowing they’re infected. Some people, especially adults, never develop noticeable symptoms at all but can still pass the virus to others.
Even after someone feels better, the virus continues to shed in stool for weeks. This extended shedding period is a major reason HFMD is so difficult to contain once it enters a household or childcare setting.
Where Outbreaks Happen Most
Daycare centers and schools are the classic hotspots. Young children are in close physical contact throughout the day, share toys, and aren’t yet reliable about handwashing. The virus spreads quickly in these environments and then travels home to siblings and parents.
Any setting where people share close quarters can fuel an outbreak. Summer camps, college dormitories, and households with multiple young children are all common environments. HFMD peaks in summer and early fall in temperate climates, though it circulates year-round in tropical regions.
Adults Can Get It Too
HFMD is often thought of as a childhood illness, and children under five are indeed the most frequently affected group. But adults absolutely catch it, particularly parents and caregivers in close contact with sick children, or anyone with a weakened immune system.
The experience differs somewhat for adults. Most healthy adults have milder symptoms than children, and some never develop symptoms at all. When adults do get sick, it typically starts with a few days of feeling like a mild cold: low fever, sore throat, runny nose, and poor appetite. Those early symptoms fade and are followed by the signature blisters on the palms, soles of the feet, and inside the mouth. Adults may also develop an itchy rash on the knees, elbows, genitals, or buttocks, along with swollen lymph nodes in the neck. Notably, adults don’t always get the obvious pus-filled blisters that are the hallmark of HFMD in children, which can make the illness harder to recognize.
Which Viruses Cause It
HFMD isn’t caused by a single virus. Several members of the enterovirus family can trigger it. Coxsackievirus A16 is the most common culprit in the United States. Coxsackievirus A6 also causes HFMD and tends to produce more severe symptoms, including larger blisters and more widespread rashes. In East and Southeast Asia, enterovirus 71 (EV-A71) is a significant cause and has been linked to larger outbreaks. Because multiple viruses cause the disease, you can get HFMD more than once in your lifetime if you encounter a different strain.
How to Reduce Your Risk
There is no vaccine for HFMD available in the United States, so prevention comes down to hygiene. Frequent handwashing with soap and water is the single most effective measure, especially after diaper changes, after using the bathroom, and before preparing food. Alcohol-based hand sanitizers work as a backup but are less effective against enteroviruses than thorough soap-and-water washing.
Disinfecting frequently touched surfaces like doorknobs, light switches, and shared toys helps reduce the window of surface transmission. If someone in your household is sick, avoid sharing cups, utensils, and towels. Try not to touch blisters directly, and wash your hands immediately if you do.
Keeping a sick child home from daycare or school during the first week of illness, when contagiousness peaks, limits spread to other children. But because the virus sheds before symptoms appear and continues shedding in stool for weeks afterward, even perfect isolation won’t eliminate transmission entirely. This is part of why HFMD is one of the most common childhood infections worldwide.