How to Tell Hand, Foot and Mouth Disease Apart from Chickenpox

When a child (or adult) develops a fever and a rash, it’s natural to worry. Two common viral illnesses—hand, foot and mouth disease (HFMD) and chickenpox—can look similar at first glance. Yet they have distinct patterns, timelines and symptoms. Understanding these differences helps you manage symptoms effectively and know when to seek medical advice.

Below is a clear guide to tell hand, foot and mouth disease apart from chickenpox, based on trusted sources such as the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).

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1. Causes and Contagious Period

Hand, Foot and Mouth Disease

• Caused most often by coxsackievirus A16 or enterovirus 71.
• Highly contagious: spreads through saliva, nasal droplets, blister fluid and stool.
• Contagious from a few days before symptoms start until mouth ulcers and blisters have healed (usually 7–10 days).

Chickenpox (Varicella)

• Caused by the varicella-zoster virus.
• Spreads via respiratory droplets and direct contact with blisters.
• Contagious from about 1–2 days before the rash appears until all blisters have crusted over (usually 5–7 days after rash onset).

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2. Typical Age Groups

• HFMD is most common in children under 5, though older children and adults can get it.
• Chickenpox can affect any age but is more severe in teens and adults. Many people now avoid chickenpox thanks to vaccination, but unvaccinated individuals remain at risk.

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3. Incubation Period

• HFMD incubation: 3–6 days after exposure.
• Chickenpox incubation: 10–21 days after exposure.

A longer incubation period for chickenpox means you may not connect a rash to a known exposure until weeks later.

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4. Onset and Initial Symptoms

Both illnesses start with a mild fever and feeling unwell. Key differences include:

Hand, Foot and Mouth Disease Symptoms

• Fever often low-grade (38–39°C / 100–102°F).
• Sore throat, reduced appetite.
• Mouth pain from small, red spots that become blisters or ulcers in the mouth (especially on the tongue, gums and inside cheeks).
• Irritability in babies and toddlers.

Chickenpox Symptoms

• Fever can be higher (up to 39–40°C / 102–104°F).
• Headache, body aches and chills may be more pronounced.
• Mild cough or runny nose sometimes precedes rash.
• No painful mouth ulcers.

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5. Rash Appearance and Distribution

Feature	Hand, Foot and Mouth Disease	Chickenpox
Rash type	Flat red spots → small blisters	Small red bumps → fluid-filled blisters
Location	Hands, feet, sometimes buttocks & legs	Trunk, face, scalp, sometimes limbs
Mouth involvement	Yes, painful ulcers/vesicles	Rare in mouth
Lesion stages	Typically all at same stage	Lesions in different stages—new bumps, blisters and crusts appear together
Itching	Mild to none	Intense itching

HFMD blisters are usually few but painful. Chickenpox blisters can number in the hundreds and are intensely itchy.

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6. Progression and Duration

Hand, Foot and Mouth Disease

• Fever and sore throat appear first.
• Mouth sores develop 1–2 days later.
• Rash on hands and feet follows, peaking around day 3.
• Most symptoms resolve in 7–10 days.

Chickenpox

• Rash appears 1–2 days after fever begins.
• New lesions develop for 3–5 days.
• Crusting starts around day 5–7, finishing by day 10–14.
• Full recovery usually takes 2–3 weeks.

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7. Complications and When to Worry

While both illnesses are usually mild in healthy children, watch for:

Hand, Foot and Mouth Disease

• Dehydration due to painful mouth sores making it hard to swallow.
• Rare complications: viral meningitis or encephalitis (signs include severe headache, stiff neck, confusion).

Chickenpox

• Bacterial skin infections from scratching.
• Pneumonia (more common in adults).
• Rare complications: encephalitis, cerebellar ataxia (uncoordinated movements).

Seek urgent care if your child:

• Refuses all fluids, shows signs of dehydration (dry mouth, no tears when crying, sunken eyes).
• Has a high fever (>39°C/102°F) lasting more than 3 days.
• Develops severe headache, stiff neck, confusion, difficulty breathing or seizures.
• Shows any rash that spreads rapidly or looks infected (increasing redness, warmth, swelling, pus).

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8. Management and Home Care

For both illnesses, treatment is mainly supportive:

• Encourage plenty of fluids: water, breast milk or formula, ice pops, diluted electrolyte solutions.
• Use age-appropriate pain relievers: acetaminophen or ibuprofen (never aspirin in children).
• For mouth pain in HFMD: cool liquids, soft foods (yogurt, mashed potatoes), saltwater rinses for older kids.
• For chickenpox itch: apply calamine lotion, consider antihistamines (with doctor’s OK), keep nails short and clean.

Isolating your child at home until they’re no longer contagious helps prevent spread. Good hand hygiene and disinfecting surfaces are key.

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9. When to Use a Symptom Checker

If you’re still unsure whether it’s hand, foot and mouth disease or chickenpox—or another rash illness—you might consider doing a free, online symptom check, using the doctor approved Ubie Symptom Checker. This tool can guide you on next steps and when to seek medical care.

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10. Final Tips and Talking to Your Doctor

• Keep track of symptom onset, fever patterns and rash progression.
• Take clear photos of the rash to show during a telehealth or in-office visit.
• Ask about vaccination status for chickenpox; an unvaccinated child with blisters is more likely to have varicella.
• Remember that neither illness has a specific cure—focus on comfort and hydration.

Always speak to a doctor if you notice any life-threatening or serious signs, or if you have concerns about dehydration, breathing difficulty or neurological symptoms. Early medical advice ensures the best outcome.

Stay informed, stay calm, and don’t hesitate to seek professional care when in doubt.