About this symptom
A rash is a change in the skin: patches, spots, bumps or blisters that may look red, pink, darker or paler than the skin around them, and may itch, sting or hurt. On brown and black skin the colour can be harder to see, so feel the skin as well as look.
Rashes have many causes, including allergies, infections, long-term skin conditions such as eczema, and reactions to medicines. Most are harmless and clear up, but a few come with serious illness.
Possible causes
This is not a diagnosis. These are the causes doctors think about, with the ones that are most urgent to rule out first.
- MeningitisA rash of small red or purple spots or blotches that does not fade under a glass, with high fever, severe headache, stiff neck or confusion. Not everyone gets a rash.Read about it
- Severe allergic reactionA raised, itchy or swollen rash with swelling of the lips, mouth, tongue or throat, trouble breathing or fainting. Foods, medicines and insect stings can set it off.
- Reaction to a medicineRarely serious: a spreading rash with painful, blistered or peeling skin and a sore mouth or eyes. Some epilepsy medicines, antibiotics and painkillers are linked.
- DengueHigh fever, severe headache, pain behind the eyes, muscle and joint pain, and sometimes a rash, after a bite from a mosquito that bites in the day.Read about it
- MeaslesA blotchy rash of raised spots that join together, with fever and other illness. It is usually not itchy and is harder to see on brown and black skin.Read about it
- HivesRaised bumps or patches of many shapes and sizes that itch, sting or burn, set off by foods, medicines, insect bites, heat and other triggers. Usually better within a few days.
- EczemaSkin that is itchy, dry and cracked. A doctor can confirm it and advise on treatment.Read about it
- Fungal skin infectionsRingworm is usually a ring-shaped rash that may be scaly, dry, swollen or itchy, and the colour may be less noticeable on brown and black skin.Read about it
When to get help
Also get emergency care for:
- Blue, grey or pale skin, or sudden dizziness, confusion or fainting
- A rash spreading across the body with painful, blistered or peeling skin, or a sore or swollen mouth or eyes, especially after a new medicine
- Severe tummy pain, repeated vomiting, or bleeding from the nose or gums during or after a fever with a rash
The glass test: press the side of a clear glass firmly on the rash. If the spots stay visible through the glass, get emergency care. On brown and black skin, check the palms, soles, lips, tongue and inside the eyelids.
See a doctor soon, the same day if you can, if you have:
- A rash with a fever, or feeling generally unwell (the same day)
- A rash that is spreading, or that keeps coming back
- A rash that started after a new medicine
- Hives or an itchy rash that has not improved after 2 days
- A rash that could be measles
- A rash you cannot explain that has not improved in a week
A mild rash with an obvious cause that is easing, and none of these signs, can wait for a routine visit.
What you can do at home
If any emergency sign is present, do not wait at home: get help first and take the medicines you use with you.
Do
- Do the glass test, and note when the rash began
- Write down new foods, medicines, soaps or insect bites
- For hives, a pharmacist can advise on antihistamines; tell them about any long-term condition first
Do not
- Do not wait to see if a rash with fever, or a spreading rash, gets better
- With a fever and rash in mosquito season, do not take anti-inflammatory painkillers such as ibuprofen or aspirin until a doctor has ruled out dengue
- Do not drive yourself if you have an emergency sign
What the doctor will do
The doctor will look at the rash and ask when it began, where it is, whether it itches or hurts, whether you have a fever, and what you ate, touched, took or were bitten by, including any new medicine.
Many rashes can be recognised from how they look and your history. If dengue is suspected, a blood test or rapid test is used, usually in the first week of illness. A rash that does not clear may be seen by a skin specialist (dermatologist).
Treatment depends on the cause. Hives are treated with antihistamines, a serious medicine reaction needs hospital treatment and the medicine is stopped, and dengue is managed with rest, fluids and paracetamol while watching for warning signs.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“If the rash does not itch or hurt, it is nothing serious.”What is true?
Fact
Do not judge a rash by itch or pain. A measles rash is usually not itchy, and the glass test works whatever the rash feels like. Go by the warning signs on this page.
Myth“A rash is only heat or an allergy, so a cream from the chemist is enough.”What is true?
Fact
Many rashes are harmless, but rashes also come with infections such as measles and dengue, and after medicines. A rash with fever, spreading, blistering or peeling skin, or swelling of the lips or throat needs a doctor, and some of these are emergencies.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
How do I do the glass test?
Press the side of a clear glass firmly against the spots. If they stay visible through the glass and do not fade, get emergency care at once, as this can be a sign of meningitis. On brown and black skin, check paler areas such as the palms, soles, lips, tongue and inside the eyelids. Not everyone with meningitis gets a rash, so go by the other signs too.
Can a rash be a sign of dengue?
Yes. Dengue often starts with a high fever, severe headache, pain behind the eyes and muscle and joint pain, and a rash can be part of it. See a doctor the same day for a fever with a rash. Severe tummy pain, repeated vomiting or bleeding from the nose or gums needs immediate medical care.
A rash started after I began a new medicine. What should I do?
Serious reactions are rare, but tell a doctor which medicine you started and when. If the rash is spreading, the skin is painful, blistered or peeling, or your mouth or eyes are sore or swollen, get emergency care and take the medicines you use with you.