Herpangina — Blisters at the Back of the Throat and a Week of Managing Dehydration

Lead

In the middle of summer, a high fever appears suddenly — 39–40°C (102–104°F). You look at the back of the throat and see a cluster of small blisters. There is no rash on the hands or feet. This is the classic presentation of herpangina. Like hand, foot, and mouth disease, it is caused by enteroviruses, and the two illnesses are frequently confused — the key difference is the distribution of lesions. Herpangina lesions are confined to the throat; HFMD also involves the hands, feet, and sometimes buttocks.

The greatest risk in herpangina is not the high fever itself. It is dehydration caused by the child being unwilling to swallow because of throat pain. Knowing this in advance makes the difference between a difficult week and a well-managed one.

The Virus and the Seasonal Pattern

Herpangina is caused primarily by Coxsackievirus A subtypes (A2, A4, A6, A10, and others), and also by EV-A71 in some cases [1, 4]. Studies of herpangina on its own are scarcer than combined HFMD/herpangina reports, but a surveillance study of 190 children with herpangina in Beijing found enterovirus in 69%, most often CV-A6, CV-A4, and CV-A10 [4]. Because several virus types cause it, a child who has had herpangina once can catch it again from a different type [3].

Outbreaks peak in summer. In Japan's national surveillance, reports from roughly 3,000 pediatric sentinel clinics alone reached about 126,000 by week 28 of the large 2023 outbreak (a count that excludes patients seen at non-sentinel clinics). In those reports, children aged 5 and under made up 88% of cases, concentrated between ages 1 and 4 [2]. Herpangina and HFMD together define the characteristic summer infectious disease picture for young children.

The distinction from HFMD: in HFMD, lesions appear on the hands, feet, and inside the mouth. In herpangina, blisters appear only inside the mouth — specifically at the back, on the tonsillar pillars and soft palate (the structures at the entrance to the throat). "No rash on the hands or feet" is the key diagnostic feature.

Symptoms and Course

Onset is an abrupt high fever, typically 39–40°C (102–104°F). At roughly the same time, two to ten small blisters appear at the back of the throat. The blisters rupture quickly into shallow ulcers (aphthae) and cause significant pain. This pain is the central management problem.

When throat pain prevents drinking, dehydration can develop within 24–48 hours. Younger children have smaller fluid reserves and reach the threshold faster.

Fever usually falls on its own in two to four days [3]. The throat blisters and ulcers heal within about a week. Lasting complications do not occur in the typical case.

Managing the Dehydration Risk

Maintaining fluid intake is the top priority in herpangina care. When the child refuses normal liquids, these approaches often help:

• Cold drinks, ice cream, chilled gelatin desserts — cold and non-irritating
• Avoiding hot, spicy, or acidic foods and drinks, which worsen the pain
• Offering oral rehydration solution (ORS such as OS-1, chilled) in small, frequent amounts

When to seek medical care: no urination for six hours or more, lethargy or reduced responsiveness, or the child is essentially unable to drink at all. These are signs of potential dehydration.

Infection Control

The main transmission routes are droplet, contact, and oral (fecal-oral). Even after recovery, the virus continues to be shed from droplets and nasal secretions for one to two weeks, and in stool for several weeks to several months [3]. Japan's national infection-control guideline for daycare centers sets the benchmark for returning as "no lingering effects of fever or mouth blisters and ulcers, and eating usual meals." The same guideline notes that keeping children home does little to stop spread and, given how long shedding lasts, is not realistic anyway; it asks that handwashing after bowel movements and diaper changes be kept up after return [3]. Return to preschool or swimming pools depends on each facility's policy; check with the facility once the child has recovered.

Putting It Into Practice

• "High fever + blisters at the back of the throat, no rash on hands or feet" — this combination points to herpangina
• Prioritize keeping fluid intake up, using cold foods as a tool — hydration is what the week is about
• Six hours without urination or marked lethargy → dehydration risk; see a doctor
• Log fever onset date, peak temperature, and how fluid intake changes from day to day — this makes it far easier to communicate the course if you contact the clinic
• Fecal shedding continues after recovery; sustain handwashing habits for a while after symptoms resolve

Summary

Herpangina resolves on its own in the great majority of cases within one week. The single most important thing to track is whether the child can drink. The throat pain is real and the reluctance to swallow is real — the work of the week is finding ways around it. Watching whether fluids are going in, not the height of the fever, is the core of home management.

References

1. Ho M, Chen ER, Hsu KH, et al. An epidemic of enterovirus 71 infection in Taiwan. N Engl J Med. 1999;341(13):929–935. doi:10.1056/NEJM199909233411301. PMID: 10498487.
2. National Institute of Infectious Diseases Japan. IDWR 2023 week 28, notable infectious diseases: herpangina and RSV infection [in Japanese]. 2023. https://id-info.jihs.go.jp/surveillance/idwr/rapid/2023/28/article/rs-virus/index.html
3. Children and Families Agency, Japan. Guidelines for infection control in daycare centers (2018 revision, partially revised May 2023), Appendix 1 (19) Herpangina [in Japanese]. https://www.cfa.go.jp/assets/contents/node/basic_page/field_ref_resources/e4b817c9-5282-4ccc-b0d5-ce15d7b5018c/c60bb9fc/20230720_policies_hoiku_25.pdf
4. Zhao TS, Du J, Li HJ, et al. Molecular epidemiology and clinical characteristics of herpangina children in Beijing, China: a surveillance study. PeerJ. 2020;8:e9991. doi:10.7717/peerj.9991. PMID: 33088614.