Hand, Foot and Mouth Disease and Herpangina: Fluids and When to See a Doctor

Hello. I am Shunichi Gamo, MD, PhD, a board-certified pulmonologist and the director of Sendai Airport North Clinic.

This year (2026), as in most years, reports of hand, foot and mouth disease and herpangina rose from around May, and the national weekly infectious disease report featured them as “infectious diseases to watch”[1]. As of early July, the scale of the outbreak was about average and no large outbreak had been confirmed[1]. However, even though the peak is in summer, hand, foot and mouth disease is characterized by continuing at a low level from autumn into winter[1]. Your child has a fever, complains of mouth pain, and refuses both food and drink. Many families in this situation are not sure what to do.

Let me start with the conclusion: the thing to watch most closely in these two illnesses is dehydration (the body running short of water) because the mouth hurts too much to drink. More than the height of the fever or the number of spots, look at “whether your child is drinking and passing urine.”

This article explains the features of hand, foot and mouth disease and herpangina, how to give fluids that do not sting, signs of rare complications, spread to adults, virus shedding in stool, and guidelines for returning to nursery school or school, including data from research papers.

From October 4, 2026, we also run the fever clinic on Sundays and holidays
10:00 to 15:00 (no lunch break). No appointment is needed; you are seen by checking in on the day. We tell you the PCR test result on the same day. On Sundays and holidays we run the fever clinic only; there is no general outpatient clinic and no IV drip service. We are closed on Sunday, October 25, and from November the clinic is open on Sundays and holidays as a rule. Notice about the Sunday and holiday fever clinic

[Conclusion] What to watch is not the height of the fever but “whether your child is drinking and passing urine”

First, here is a rough summary of when to see a doctor.

If you are unsure, you can consult the children’s medical advice phone line (#8000).

What are hand, foot and mouth disease and herpangina? [Both are summer colds caused by enteroviruses]

Both are so-called “summer colds” caused by viruses of the genus Enterovirus[1][2]. Hand, foot and mouth disease is caused by coxsackievirus A16, A6, A10, enterovirus 71, and others, and herpangina mainly by group A coxsackieviruses[1][2]. Because there are many causative viruses, a child who has had the illness once can catch it again and again from a different virus[3].

Here is a rough table of the differences between the two.

	Hand, foot and mouth disease	Herpangina
Incubation period (from catching it to symptoms)	3 to 5 days[1]	2 to 4 days[2]
Fever	Occurs in about 1 in 3 children, and is mostly 38°C or lower[1]	Starts with a sudden high fever (38 to 40°C) that goes down in about 2 to 4 days[2]
Inside the mouth	Blisters or small ulcers (sores where the lining has worn away) toward the front of the mouth[1][2]	Blisters of 1 to 5 mm on the upper back of the throat (around the soft palate), soon becoming shallow ulcers[2]
Rash on hands and feet	Blisters of 2 to 3 mm on the palms, soles, and tops of the feet. They can also appear on the elbows, knees, and buttocks[1]	None[2]
Age most affected	Half are 2 years old or younger[1]	More than 90% are 5 years old or younger, most commonly age 1[2]
Time to recover	3 to 7 days. The blisters do not form scabs[1]	The fever lasts 2 to 4 days, and the rash in the mouth fades a little later[2]

In fact, more children with hand, foot and mouth disease have no fever than have one[1]. Herpangina, on the other hand, starts with a sudden high fever and can cause a febrile seizure[2][3]. Whether the illness is severe or mild is not decided by whether the fever is high or low. What you need to look at is “whether your child is drinking,” which I discuss next.

Nails may fall off after hand, foot and mouth disease

In hand, foot and mouth disease caused by coxsackievirus A6, which has been common in recent years, the rash can be larger and spread so widely that it is mistaken for chickenpox[1][3]. In addition, onychomadesis (nails falling off) has been reported a few weeks after onset[1][3]. It is startling, but it is a known phenomenon after hand, foot and mouth disease. If you are worried, please ask us at your visit.

The main thing to watch for is dehydration [the mouth hurts too much to drink]

Most cases of hand, foot and mouth disease and herpangina get better in a few days[1][2]. Treatment is mainly symptomatic therapy, which eases symptoms such as fever and mouth pain[1][2].

So why is a doctor’s visit sometimes needed? Because the pain in the mouth keeps the child from drinking and leads to dehydration. In herpangina, mouth pain can cause irritability, refusal to eat, trouble feeding (not being able to take breast milk or formula), and dehydration as a result[2]. In explanations of hand, foot and mouth disease as well, “above all, it is most important not to let the child run short of fluids,” and sometimes an IV drip is needed[1].

There is a randomized trial from a pediatric emergency department in Melbourne, Australia, that studied 100 children aged 6 months to 8 years who could not drink because of mouth sores[4]. The children had conditions such as hand, foot and mouth disease and herpetic stomatitis and had become unable to take fluids at home[4]. In a secondary analysis, 72% were mildly dehydrated and 5% were moderately dehydrated when they arrived[4]. This shows how many children become dehydrated just from “not being able to drink because the mouth hurts.”

This trial compared a topical local anesthetic applied inside the mouth (a medicine that numbs the area where it is applied; 2% lidocaine) with a placebo (a substance with no active ingredient)[4]. The median amount (the middle value) drunk in the hour after the medicine was 8.49 mL per kg of body weight with lidocaine and 9.31 mL with placebo, so there was no difference[4]. This trial was done in an Australian emergency department, and the medicines and policies used differ by country and by medical institution. Still, this trial did not show that a numbing medicine applied in the mouth increases how much a child drinks. When the pain is strong, please consult a doctor; the basic approach is to stay with your child and give small sips little by little.

Also, in this trial most of the doctors judged that drinking more than 9 mL per kg of body weight in an hour was “drinking enough,” and less than 5 mL was “not enough”[4]. For a child weighing 10 kg, that is about 90 mL in an hour. This is not a Japanese standard for seeing a doctor but the sense of emergency doctors in Australia; still, it can serve as a rough reference for “how much drinking is reassuring.”

Signs of dehydration

As dehydration progresses, the child vomits even what is given to drink, creating a vicious circle: cannot drink, dehydration, cannot drink. Please see a doctor before that happens, as soon as the amount your child drinks starts to drop.

How to give fluids [things that do not sting, little by little]

With sores in the mouth, children refuse anything that stings and will not drink it. The trick is “things that do not sting, a little at a time, many times.”

Not eating is nothing to worry about for a few days. Please put drinking before eating. Ice cream and pudding give fluid and sugar at the same time, so during this illness they count as a proper meal.

Use a pain reliever so your child can drink

When the pain is too strong to drink, one approach is to use the prescribed acetaminophen and give fluids once the pain has eased. Explanations of herpangina also say that acetaminophen and similar medicines may be used for fever and headache[2].

A child’s dose is decided by body weight, so use prescribed medicines (including suppositories) in the amount and at the intervals instructed. For over-the-counter children’s medicines, always follow the age and dose on the label. Do not use adult over-the-counter medicines or a sibling’s medicine. For a baby under 3 months old, do not use medicine on your own; see a doctor first.

How to give fluids when your child vomits and cannot keep them down is described in detail in the article on what to do when a child with fever and vomiting cannot drink.

Rare complications [signs of meningitis or encephalitis: headache, vomiting, limpness, seizures]

Both illnesses can rarely be complicated by meningitis (inflammation of the membranes that surround the brain) or encephalitis[1][2][3]. Meningitis causes headache and vomiting in addition to fever, and encephalitis causes seizures and impaired consciousness[3]. In herpangina, acute myocarditis (inflammation of the heart muscle) has also been reported[2].

Let’s look at the numbers to see how rare this is. There is a study of 7,200,092 suspected cases of hand, foot and mouth disease (about 7.2 million) reported in China from 2008 to 2012[5]. Severe heart, lung, or nervous system complications occurred in 82,486 (1.1%), and 2,457 (0.03%) died[5]. Of the laboratory-confirmed deaths, 93% were caused by enterovirus 71[5].

In other words, severe complications occur in about 1 in 100, and this also differs by the type of virus. However, this is data from China, where many severe cases occur. In Japan, severe cases are said to be not so common[6]. The situation differs by country and by the virus that is circulating.

“A fever that lasts” and “limpness” are signs of spread to the nervous system

So which children should we watch more closely? There is a study of 725 children admitted with hand, foot and mouth disease in Sarawak, Malaysia, from 2000 to 2006[7]. It found that three things were risk factors for spread to the nervous system: a fever lasting 3 days or more in total, a peak temperature of 38.5°C or higher, and lethargy (limpness)[7].

When this was checked in other children, among 250 in whom spread to the nervous system was suspected from a cerebrospinal fluid test (the fluid surrounding the brain and spinal cord), 65% met two or more of these three[7]. Among 186 without spread, it was 30%[7]. The odds ratio (a multiple comparing how likely something is) was 4.27, and the 95% confidence interval (the range in which the true value almost surely lies) was 2.79 to 6.56[7].

Japanese explanations of hand, foot and mouth disease also say to watch for progression to meningitis or encephalitis when there is lethargy, headache, vomiting, high fever, or a fever lasting 2 days or more[1]. In herpangina, watch for meningitis when there is headache or vomiting in addition to fever[2]. If even one of the following signs applies, see a doctor without waiting for morning, even at night or on a holiday.

If a seizure lasts 5 minutes or more, the child does not respond when called, or the child is struggling badly to breathe, call 119 without hesitation. For a first seizure, see a doctor on the spot even if it stops quickly and even at night. If you are unsure, you can consult #8000.

Adults can get it too [it spreads within the family]

Hand, foot and mouth disease and herpangina are often thought of as children’s illnesses, but adults get them too. Most people of school age and older have already had these viruses, so illness in adults is not common, and it tends to be more frequent in men[1].

However, because there are many causative viruses, even a person who has had the illness once can catch a different virus again and again[3]. The same is true of adults. Even so, a mother or father who has been caring for a sick child may notice a few days later, from mouth pain or a rash on the hands and feet, that “I caught it.” If an adult has pain in the palms or soles or ulcers in the mouth, please tell the doctor about your child’s illness when you see one.

The routes of spread are droplets from coughing and sneezing, hands that have touched the contents of blisters or stool, and then touching the mouth with those hands[1][2]. While caring for a sick child, wash your hands thoroughly after changing diapers and wiping noses, and avoid sharing towels and cups[1][3].

The virus is shed in stool for a long time [2 to 4 weeks after recovery, sometimes longer]

One thing I would like you to know about this illness is that the virus keeps being shed in stool for a long time. Even after symptoms have gone, the virus is shed in stool for 2 to 4 weeks and can be a source of infection[1][2]. The nursery guideline gives an even longer period, saying that the virus is shed in stool for several weeks to several months[3]. The range differs by source, but it is fine to remember “around a month after recovery, sometimes longer.”

In China, there is a study that followed the stool and throat of 34 patients with hand, foot and mouth disease (enterovirus 71)[8]. The viral genetic material was detected for up to 24 days in the throat and up to 42 days in stool[8]. In stool, it was still detected in about 20% of people 37 to 40 days after onset[8].

That does not mean you need to keep your child home for more than a month. Even after symptoms have gone, continuing to wash hands after diaper changes and bowel movements is the realistic way to prevent spread in the family and at nursery[1][3].

When can the child go back to nursery or school? [There is no uniform absence period]

The guideline for returning to nursery is given in the Children and Families Agency’s “Guidelines for Infectious Disease Control in Nursery Facilities”[3]. For both hand, foot and mouth disease and herpangina, the guideline is “no effect from fever or from the blisters and ulcers in the mouth, and able to eat the usual meals”[3].

The guideline says that keeping children home to avoid spreading the infection is “of low effectiveness and, given the long period of virus shedding, not realistic”[3]. On that basis, the idea is that children should stay home when they have a fever, a sore throat, or diarrhea, or cannot eat, and go back once their overall condition is stable[3]. These two illnesses are listed among infections for which a parent may fill in a “return-to-nursery form” after a doctor’s diagnosis, but submission is not uniformly required[3]. Handling differs by nursery, so please check with your child’s nursery.

For elementary school and above

Under the enforcement regulations of the School Health and Safety Act, neither hand, foot and mouth disease nor herpangina is among the Class 1 and Class 2 infectious diseases for which an absence period is set[1][6]. Depending on the outbreak situation, the school doctor and principal may treat them as “other infectious diseases” under Class 3[1][2].

According to the explanation of the Japan School Health Association, attendance is possible if the child’s overall condition is stable[6]. The idea is that keeping children out of school to stop an outbreak is of low effectiveness and, given the long period of virus shedding, not realistic[6]. Roughly speaking, “once the fever is down and your child can eat normally, going back to nursery or school is fine.”

About our fever clinic

Our clinic does not see patients at night. We are also closed on Thursdays. If danger signs appear during the night, please use #8000, an after-hours clinic, or an emergency department.

If “my child is starting to be unable to drink because of the fever and mouth pain” or “I would like the rash on the hands and feet to be checked,” please consult our fever clinic. Our policy is that we do not turn away anyone who comes to the fever clinic (depending on the symptoms, we may direct you to a more suitable medical institution).

Day	Hours
Mon, Tue, Wed, Fri, Sat	9:00 to 12:00 / 14:00 to 18:00
Sundays and holidays (from October 4, 2026)	10:00 to 15:00 (no lunch break, fever clinic only)
Thursday	Closed

On Sundays and holidays, we are closed on Sunday, October 25, and from November we are open every Sunday and holiday as a rule. For details, please see Notice about the Sunday and holiday fever clinic.

How a visit works (no appointment needed)

Please note that on Sundays and holidays we run the fever clinic only, with no general outpatient clinic and no IV drip service. If an IV drip seems likely to be needed, for example when the child cannot take any fluids and is limp, please go to a medical institution that can give IV drips.

It goes smoothly if you tell us the following at your visit.

Frequently asked questions (FAQ)

The fever has gone down, but my child will not eat because the mouth hurts. Should we see a doctor?

If your child can drink little by little and is passing urine as usual, not eating for a few days is nothing to worry about. Give fluids and sugar in things that do not sting, such as jelly, pudding, and ice cream. If the amount your child drinks has clearly dropped or urination is becoming less frequent, see a doctor that day or the next.

If I use a numbing medicine in the mouth, will my child be able to drink?

In a randomized trial in an Australian emergency department, a topical local anesthetic applied in the mouth (2% lidocaine) made no difference in how much children drank compared with a placebo[4]. Policies differ by country and by medical institution. When the pain is strong, please consult a doctor. The basics are to ease the pain with the prescribed acetaminophen and to stay with your child and give one spoonful at a time.

My child has hand, foot and mouth disease but no fever. Can I send them to nursery?

In the nursery guideline, the guideline for returning is “no effect from fever or from the blisters and ulcers in the mouth, and able to eat the usual meals”[3]. The idea is that a child who only has a rash and is eating normally can go. Some nurseries require a return-to-nursery form, so please check with your child’s nursery.

I (an adult) was caring for my child and now my mouth hurts and I have a rash on my hands. Did I catch it?

Adults can get it too. Adults have no immunity to a virus they have not had before, and it is quite common for it to spread within the family while caring for a sick child[1][3]. If mouth ulcers or the rash on your hands and feet are bothering you, tell the doctor about your child’s illness when you see one. Even after your symptoms settle, the virus is shed in stool for several weeks, so keep washing your hands after using the toilet[1][2].

How should I handle baths so I do not pass it to the siblings?

The routes of spread are droplets from coughing and sneezing, and hands that have touched the contents of blisters or stool[1][2]. Rather than bathing separately, it is important to avoid sharing towels and cups and to wash hands thoroughly after diaper changes and bowel movements[1][3]. Because there are several causative viruses, a household can catch different viruses one after another[3].

Can I bring my child, who cannot drink because of mouth pain, to the fever clinic on a Sunday or holiday?

Yes. The Sunday and holiday fever clinic runs from 10:00 to 15:00. We are closed on Sunday, October 25, and from November we are open every Sunday and holiday as a rule. No appointment is needed; you are seen by checking in on the day. However, on Sundays and holidays we run the fever clinic only, with no general outpatient clinic and no IV drip service. If an IV drip seems likely to be needed, for example when the child cannot take any fluids and is limp, please go to a medical institution that can give IV drips.

Summary [Mouth too sore to drink means watch for dehydration. See a doctor even at night for danger signs]

It is truly hard to give small sips to a child who is crying with mouth pain. Remember roughly these two things, “things that do not sting, a little at a time” and “the signs that mean seeing a doctor even at night,” and you will be fine. If your child is starting to be unable to drink, please do not hesitate to rely on us.

That’s all.

Disclaimer

This article is intended to provide general medical information and does not replace an examination, diagnosis, or treatment by a doctor. The content is based on medical knowledge at the time of publication, but the appropriate response differs from person to person. If you are worried about your symptoms, please consult a medical institution.

References

1. Japan Institute for Health Security (JIHS), Infectious Disease Information site. Hand, foot and mouth disease (updated July 24, 2025). https://id-info.jihs.go.jp/infectious-diseases/hand-foot-mouth-disease/index.html / Hand, foot and mouth disease (detailed version) (revised October 17, 2014). https://id-info.jihs.go.jp/infectious-diseases/hand-foot-mouth-disease/detail/index.html / IDWR 2026 Week 26, Infectious Diseases to Watch: Hand, foot and mouth disease and herpangina (as of July 1, 2026). https://id-info.jihs.go.jp/surveillance/idwr/featured/2026/26/index.html (in Japanese)
2. Japan Institute for Health Security (JIHS), Infectious Disease Information site. Herpangina (updated August 28, 2025). https://id-info.jihs.go.jp/infectious-diseases/herpangina/index.html / Herpangina (detailed version) (revised July 23, 2014). https://id-info.jihs.go.jp/infectious-diseases/herpangina/detail/index.html (in Japanese)
3. Children and Families Agency. Guidelines for Infectious Disease Control in Nursery Facilities (2018 revised edition) (partially revised May 2023, partially amended October 2023). https://www.mhlw.go.jp/content/10900000/20231010_policies_hoiku_25.pdf (in Japanese)
4. Hopper SM, McCarthy M, Tancharoen C, Lee KJ, Davidson A, Babl FE. Topical lidocaine to improve oral intake in children with painful infectious mouth ulcers: a blinded, randomized, placebo-controlled trial. Ann Emerg Med. 2014 Mar;63(3):292-9. doi:10.1016/j.annemergmed.2013.08.022 PMID: 24210368
5. Xing W, Liao Q, Viboud C, Zhang J, Sun J, Wu JT, et al. Hand, foot, and mouth disease in China, 2008-12: an epidemiological study. Lancet Infect Dis. 2014 Apr;14(4):308-318. doi:10.1016/S1473-3099(13)70342-6 PMID: 24485991
6. Japan School Health Association (public interest incorporated foundation). Explanation of Infectious Diseases to Be Prevented in Schools (Reiwa 5 revision). March 2024. https://www.gakkohoken.jp/books/archives/273 / Full text PDF: https://www.gakkohoken.jp/book/ebook/ebook_R050080/data/670/src/670.pdf (in Japanese)
7. Ooi MH, Wong SC, Mohan A, Podin Y, Perera D, Clear D, et al. Identification and validation of clinical predictors for the risk of neurological involvement in children with hand, foot, and mouth disease in Sarawak. BMC Infect Dis. 2009 Jan;9:3. doi:10.1186/1471-2334-9-3 PMID: 19152683
8. Han J, Ma XJ, Wan JF, Liu YH, Han YL, Chen C, et al. Long persistence of EV71 specific nucleotides in respiratory and feces samples of the patients with Hand-Foot-Mouth Disease after recovery. BMC Infect Dis. 2010 Jun;10:178. doi:10.1186/1471-2334-10-178 PMID: 20565813

Related articles to read when there is a fever

For the Sunday and holiday fever clinic, see Notice about the Sunday and holiday fever clinic; for how to visit, see About the pre-visit questionnaire and same-day check-in for the fever clinic. If your child vomits and cannot keep fluids down, please also see the article on what to do when a child with fever and vomiting cannot drink.