When is hand, foot, and mouth disease (HFMD) contagious?

When Hand, Foot, and Mouth Disease is Contagious

Hand, foot, and mouth disease is most contagious during the first week of illness when fever and skin lesions are present, with viral shedding continuing for 5 days in adults and 7 days in children after symptom onset, though fecal shedding can persist for several weeks. 1

Peak Infectious Period

• The highest risk of transmission occurs during the first 7 days of illness, particularly when fever and active skin lesions are present 1
• Infected adults shed virus for up to 5 days after symptoms begin, while children continue shedding for up to 7 days 1
• The viral load and infection risk decrease steadily throughout this period 1
• Pre-symptomatic transmission (before symptoms appear) has only rarely been documented, indicating most spread occurs after symptom onset 1

Extended Contagious Period

• The overall contagious period spans from 1-2 days before symptoms appear until all blisters have dried and crusted over, typically 7-10 days from symptom onset 2
• Viral shedding in stool can persist for several weeks after clinical symptoms resolve 2
• Patients should be considered potentially contagious for at least 10-14 days 2
• The incubation period ranges from 3 to 10 days before the first symptoms appear 3

Transmission Routes During Contagious Period

• Direct contact with fluid from blisters or vesicles transmits the virus 1
• Respiratory droplet contact spreads the infection 1
• Fecal-oral transmission occurs, particularly important given prolonged fecal shedding 4
• Indirect contact via contaminated surfaces and fomites (objects) can transmit disease 1
• Enteroviruses can remain viable on surfaces for up to 28 days, making environmental contamination a significant concern 2

Clinical Signs Indicating Active Infectiousness

• Fever is typically the first symptom and signals high infectiousness 1
• Active vesicles and blisters on hands, feet, and in the mouth indicate peak viral shedding 4
• Respiratory symptoms such as cough and rhinitis may be present during the infectious period 1
• Gastrointestinal symptoms including nausea, vomiting, and diarrhea may occur during active infection 1

When Patients Can Return to Normal Activities

Children can return to school or daycare only when fever has resolved without fever-reducing medications, all blisters have dried and crusted over, and at least 7 days have passed since symptom onset 2

• Waiting only for fever resolution is insufficient, as children remain contagious until all lesions have crusted 2
• Some guidelines recommend waiting until no new lesions have appeared for 48 hours 1
• Children should be excluded from swimming pools during the acute illness phase 1
• Hand hygiene should be emphasized even after returning to activities, as some viral shedding may continue 1

Critical Prevention Measures

• Hand hygiene using soap and water (not just alcohol-based sanitizers) is the single most important method of preventing transmission, as alcohol-based products are insufficient against enteroviruses 1, 2, 4
• Disinfecting potentially contaminated surfaces and fomites is essential 4
• Healthcare workers and childcare providers must follow strict infection control protocols 2
• Vesicle fluid should be considered highly infectious and appropriate precautions taken 1

Common Pitfalls to Avoid

• Allowing children to return to school before the contagious period ends can trigger outbreaks 2
• Relying solely on alcohol-based hand sanitizers is inadequate, as enteroviruses require soap and water for effective removal 2
• Overlooking environmental cleaning allows viral persistence on surfaces for weeks 2
• Underestimating the prolonged fecal shedding period (several weeks) can lead to continued transmission 2