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Rash
Category: Skin, Hair & Nails · All skin symptoms
What it can feel like
A rash is any change in the skin's appearance or texture over an area — redness, spots, bumps, blisters, scales or welts. Rashes are described by their shape and distribution before they are named, and the same rash means different things in a well child, an unwell adult, or someone who has just started a new medicine.
Possible causes
A symptom can have many causes, and most are not serious. The lists below group conditions this symptom can be associated with — common causes first. They are possibilities to discuss with a clinician, not a diagnosis.
Common causes
A rash can be associated with viral infections (many childhood illnesses), eczema, contact irritation or allergy, heat, fungal infection, and reactions to medicines — drug rashes typically start days to two weeks after a new medicine.
Other possible causes
A rash can also be associated with bacterial infections such as cellulitis or scarlet fever, with immune conditions (psoriasis, lupus), and with meningococcal disease — the critical rash that does not fade under pressure, in an unwell, febrile person.
Red flags — when to seek help promptly
- A rash that does not fade when a glass is pressed against it, with fever or feeling unwell — emergency
- A rash with blistering, skin pain, mouth or eye involvement — urgent
- A rash with swelling of the lips or tongue, or difficulty breathing — emergency
- A painful, rapidly spreading area of redness with fever
- A rash in a baby under three months, or in someone with a weakened immune system, who is unwell
What a clinician may do
A clinician will examine the rash's morphology and distribution, ask about medicines, contacts, travel and other symptoms, and test whether spots blanch under pressure. Swabs, scrapings or blood tests follow the pattern; photographs help when a rash is intermittent.
Watch: related videos
Examination and clinical videos from the MedicalVideos.com library relevant to this symptom. Some clinical footage is graphic — that is the nature of a medical video library.
Related guides on MedicalVideos.com
Frequently asked questions
What is the glass test?
Pressing a clear glass firmly against a rash: ordinary inflammatory rashes blanch (fade) because blood is pushed out of surface vessels. Spots caused by blood leaking into the skin — the meningococcal pattern — do not fade. In a febrile, unwell person, a non-blanching rash is an emergency.
When should a rash in a child worry me?
Judge the child, not just the rash: a playful, drinking, responsive child with a blanching rash is usually fine to watch at home. A drowsy, pale, poorly feeding child, or any non-blanching rash, changes everything — seek urgent care.
Related symptoms — Skin, Hair & Nails
Browse the R section of the A–Z list or return to the Symptoms A–Z hub.