Clinical summary
The differential diagnosis of rash illnesses rests on the appearance of the rash (macule, papule, vesicle), where it began and how it spread, its timing in relation to fever, oral findings, nursery or school contact history, and vaccination status. Rashes that do not fade under pressure always require prompt assessment.
How is a rash assessed?
The questions asked in the clinic largely guide the diagnosis: Where did the rash start and how did it spread? Did the fever begin before or after the rash? Is it itchy? Are there mouth ulcers? Has another child at nursery had a similar illness? Has a new medication or food been introduced?
On examination, whether the rash fades under pressure is particularly important. Purple-red spots that do not fade require urgent assessment.
Hand-foot-and-mouth disease
Caused by enteroviruses (often Coxsackie), this is common in the nursery years. After fever, painful ulcers appear in the mouth along with small blisters on the hands, feet and sometimes the buttocks.
Treatment is supportive. The main concern is reduced fluid intake because of mouth pain, so maintaining hydration and managing pain are the priorities.
Sixth disease (roseola infantum)
Usually seen between 6 months and 2 years. The typical course is 3–5 days of high fever, and a pink rash appearing on the trunk after the fever subsides. The rash is not itchy and fades quickly.
During the high-fever phase, parents are most concerned about the temperature itself; the child's general condition, fluid intake and alertness are the most important measures of assessment.
Scarlet fever
Caused by group A beta-haemolytic streptococcal infection. It begins with sore throat and fever; a fine red rash with a sandpaper texture, a strawberry-like tongue, and accentuation in skin folds such as the groin and armpits may be seen.
Why it matters
Unlike viral rashes, scarlet fever requires appropriate antibiotic treatment. Treatment matters both for rapid resolution of symptoms and for preventing late complications such as rheumatic fever. Confirmation with a throat culture or rapid antigen test may therefore be performed.
Chickenpox (varicella)
Presents with itchy lesions that progress from red spots to fluid-filled blisters and then crust over. Lesions at different stages may be present at the same time. The chickenpox vaccine is part of the national immunisation schedule.
Controlling itch and keeping nails short help prevent secondary bacterial infection.
Other viral rashes
Many ordinary viral infections can cause transient, unnamed rashes. If the child is generally well, feeding normally and the rash fades under pressure, observation may be sufficient. However, if the rash spreads rapidly, fever persists, or the child is markedly lethargic, examination is needed.
When should you seek medical care immediately?
Findings requiring assessment without delay
- Purple-red rashes that do not fade under pressure
- Fever with marked lethargy or difficulty waking
- Neck stiffness, severe headache, discomfort in bright light
- Rapidly spreading rash; swelling of the lips, tongue or eyelids
- Breathing difficulty
- Inability to drink because of mouth pain; reduced urine output
- Fever and/or rash in an infant under 3 months
Related content
- Vaccines and preventive pediatrics
- Pediatric respiratory health
- Parent Health Guide
- Frequently asked questions
Frequently asked questions
When can a child return to nursery after hand-foot-and-mouth disease?
The general approach is that the fever has settled, mouth ulcers have healed enough not to interfere with feeding, and general condition has improved. The nursery or school may also have its own policy.
When does the rash appear in sixth disease?
A pink rash typically appears on the trunk after 3–5 days of high fever has subsided. The appearance of the rash after the fever breaks is the distinguishing feature.
Are antibiotics needed for rash illnesses?
Most childhood rashes are viral and do not benefit from antibiotics. Bacterial causes such as scarlet fever do require appropriate antibiotic treatment. This distinction is made by examination and, where needed, laboratory testing — avoiding unnecessary antibiotic use.
Which rashes require urgent assessment?
Purple-red rashes that do not fade under pressure, fever with marked lethargy or difficulty waking, neck stiffness, rapidly spreading rash, swelling of the lips or eyelids, and breathing difficulty all require urgent assessment.
This content is provided for general information purposes and does not replace individual medical assessment, diagnosis or treatment.
