Rashes

A rash is any noticeable change in your skin. The skin may change colour, become raised or swollen, develop spots or blisters, or feel itchy or painful.

“Rash” describes a symptom rather than one disease. Possible causes include irritation, allergy, infection, medication reactions, and longer-term skin conditions. Appearance alone may not identify the cause because different conditions can look similar.

Skin colour also affects how a rash appears. Redness may look pink or red on lighter skin. On brown or black skin, an inflamed area may look purple, grey, dark brown, or simply darker than nearby skin.

A rash may affect one small patch, several separate areas, or much of the body. It may appear suddenly or develop over several days.

You may notice:

• Itching, burning, tenderness, or pain
• Flat or raised spots
• Dry, cracked, thickened, or scaly skin
• Swelling, welts, bumps, blisters, or crusts
• Changes in skin colour
• A ring-shaped, net-like, or uneven pattern

Notice where the rash began, how quickly it spread, and whether it fades when pressed. Other useful clues include fever, joint pain, breathing problems, recent illness, travel, insect bites, new medicines, or contact with a new product.

Irritant contact dermatitis happens when something damages or repeatedly irritates the skin. Common triggers include soaps, detergents, cleaning products, frequent handwashing, and friction. The affected skin often becomes dry, cracked, itchy, or sore.

Allergic contact dermatitis is an immune reaction after skin contact with a substance such as nickel, fragrance, hair dye, or a plant. It may cause intense itching, swelling, or small blisters. A reaction can appear hours or days after contact.

Eczema commonly causes itchy, dry, inflamed patches. It may come and go and can worsen with heat, dry weather, stress, or irritating products.

Hives are raised, itchy welts that can change shape or move around. Infections, medicines, foods, heat, pressure, or other triggers may cause them. Sometimes no trigger is found.

Minor infections can also cause rashes. Fungal infections may produce scaly or ring-shaped patches. Viral illnesses can cause widespread spots, often with other symptoms. Bacterial infections may make an area warm, painful, swollen, or crusted.

Less common possibilities include psoriasis, autoimmune conditions, reactions to sunlight, insect infestations, and side effects from medicines. A new rash after starting a medicine needs medical advice, even if the medicine seems unrelated.

Call emergency services if a rash occurs with:

• Trouble breathing, throat tightness, faintness, or swelling of the tongue
• Rapidly developing blisters, widespread peeling, or raw skin
• Painful sores affecting the eyes, mouth, or genitals
• A purple or red rash that does not fade under pressure, with fever or severe illness

These features may indicate a serious allergic reaction, severe medication reaction, or significant infection.

Seek same-day medical care if the rash is rapidly spreading, very painful, or accompanied by fever. You should also get prompt advice if the skin around it is becoming hot and swollen, pus is present, or red streaks extend from the area.

A rash near the eye, a widespread rash during pregnancy, or a rash in someone with a weakened immune system also deserves prompt assessment.

Book a routine appointment if the rash lasts more than a few weeks, keeps returning, disrupts sleep, or does not improve with basic care. Arrange a review sooner if a new medicine may be responsible. Do not stop an essential prescribed medicine unless a clinician advises it, except when emergency help is needed for a severe reaction.

A clinician will usually ask when the rash started, where it first appeared, and how it has changed. They may ask about itching, pain, illness, medicines, allergies, travel, work, hobbies, pets, and new skin or cleaning products.

The skin’s pattern and location often provide useful clues. The clinician may examine your nails, scalp, mouth, or other skin areas.

Tests are not always needed. Depending on the suspected cause, testing may include a skin scraping for fungus, a swab for infection, blood tests, allergy patch testing, or removal of a tiny skin sample for examination.

Photographs taken as the rash changes can be helpful, especially if it comes and goes.

Treatment depends on the cause. Options may include moisturisers, anti-inflammatory creams, antihistamines like cetirizine or loratadine, antifungal treatment, antibiotics like amoxicillin or doxycycline, or treatment for an underlying condition. Not every rash benefits from these medicines, so uncertain or persistent rashes should be assessed.

While waiting for the rash to settle:

• Use cool compresses and avoid hot showers
• Wash gently with lukewarm water and an unperfumed cleanser
• Apply a fragrance-free moisturiser to dry, unbroken skin
• Wear loose, breathable clothing
• Avoid scratching and keep fingernails short
• Stop newly introduced cosmetics or non-essential skin products

A pharmacist can advise whether a non-prescription antihistamine or mild steroid cream is suitable. Some antihistamines cause drowsiness. Steroid like prednisone or hydrocortisone creams can worsen certain infections or cause problems when used incorrectly, especially on the face, genitals, or broken skin.

Avoid sharing towels if an infection is possible. Do not pop blisters or apply leftover prescription creams from a previous rash.

A mild irritation or hive outbreak may improve within days once the trigger is removed. Dermatitis, eczema, and psoriasis may last longer or return in flares. Infections improve according to their cause and the treatment used.

Skin colour changes can remain after the active rash has healed, particularly on darker skin. These marks often fade gradually. Seek follow-up if symptoms worsen, return frequently, or do not improve as expected.

Is every rash contagious?

No. Dermatitis, eczema, hives, and medicine reactions do not spread between people. Some fungal, viral, bacterial, or parasitic causes can spread. Until the cause is clear, avoid sharing towels and follow careful hand hygiene.

Should I press a glass against the rash?

Pressing a clear glass against spots can show whether they fade under pressure. A rash that does not fade is not always dangerous, but one accompanied by fever or severe illness needs emergency assessment. Do not let this test delay help.

Can stress cause a rash?

Stress can worsen itching, hives, eczema, and psoriasis. It should not automatically be assumed to be the cause, particularly when a rash is new, painful, or accompanied by other symptoms.

Can I use photographs to identify it?

Photographs may help document changes, but they cannot reliably confirm every cause. Lighting and skin tone can alter the appearance, and diagnosis may depend on symptoms, medicines, exposures, and examination.