The combination of skin rash and fever is a high-urgency clinical scenario — it can represent life-threatening meningococcal disease, or common and benign viral exanthems. Rapid triage by rash character is essential.
The key triage question with fever + rash is whether the rash is blanching (pressed firmly with a glass — does it disappear?) or non-blanching. A non-blanching petechial or purpuric rash with fever is meningococcal disease until proven otherwise — call emergency services immediately. Blanching rashes with fever are usually viral and benign.
Viral exanthem (roseola, fifth disease, rubella)
Most common cause in children. Blanching macular or maculopapular rash. Generally benign and self-limiting.
Scarlet fever (Group A Streptococcus)
Sandpaper-textured, confluent blanching rash starting on trunk after strep throat. Requires antibiotic treatment.
Meningococcal disease
Non-blanching petechial/purpuric rash with high fever — medical emergency. Can progress to septicaemia and death within hours.
Drug reaction (DRESS, Stevens-Johnson)
Fever + widespread rash 1–8 weeks after new medication. Mucosal involvement (SJS) is an emergency.
Rapidly moving urticarial track-like rash around trunk with systemic symptoms. Specific to Strongyloides autoinfection.
Typhoid fever
Rose spots — pale pink blanching macules on the trunk, 2–4 mm, in a febrile returning traveller.
Dengue fever
Diffuse blanching maculopapular rash with high fever, severe headache, and bone pain — tropical travel history key.
The glass test: press a clear glass firmly against the rash. If the rash disappears (blanches) under pressure — it is likely benign (viral). If it stays visible (does NOT blanch) under the glass — it may be a petechial or purpuric rash indicating meningococcal disease. This requires a 999/112 emergency call immediately.
Key parasite-related rashes with fever include: larva currens from strongyloidiasis (rapidly moving urticarial rash, 5–10 cm/hour); rose spots from typhoid-like illness; and urticaria from trichinellosis or echinococcosis (allergic response to parasite antigens). Travel history to endemic regions is crucial.
Not always. Viral exanthems (roseola, fifth disease) are contagious; drug rashes are not. Meningococcal disease has low secondary attack rates but requires close-contact prophylaxis. Strongyloidiasis and other parasitic rashes are not contagious to others. The cause determines isolation and prophylaxis requirements.
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