Condition guide

Drug rash and medicine allergy

Also known as Drug allergy, Drug eruption, Medicine reaction, Fixed drug eruption, Stevens Johnson syndrome, DRESS.

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In short

A drug rash, or drug eruption, is a skin reaction to a medicine. Most are mild, itchy, measles like rashes or hives that settle once the medicine is stopped under a doctor's advice, but a small number are severe reactions that can be life threatening. A rash after a new medicine is an emergency if it blisters or peels, causes sores in the mouth, eyes or genitals, comes with fever and feeling very unwell, or comes with swelling of the face, lips or throat or difficulty breathing.

Typical signs

Small red or darker spots and bumps that look like measles, usually on the trunk first, often itchy
Itchy, raised welts that come and go, sometimes with swelling
A round, red or purplish patch that leaves a dark mark and returns in exactly the same place each time a medicine is taken
A rash that starts days to several weeks after a new medicine
Blisters, peeling skin or sores in the mouth, eyes or genitals, which need emergency care

When to see a dermatologist

Call 112 or 108, or go to the nearest emergency department, if a rash blisters, peels or looks burnt, or there are sores in the mouth, eyes or genitals
Get emergency help at once for swelling of the face, lips, tongue or throat, wheezing or difficulty breathing, or a rash with high fever and feeling very unwell
Take all your medicines and their strips with you, and do not drive yourself
For a mild rash, contact the doctor who prescribed the medicine the same day, and do not stop medicines such as epilepsy or heart medicines on your own
You have a dark patch that keeps coming back in the same place
You want to know which medicines to avoid after a reaction

Signs vary from person to person and several skin conditions look alike. Only an examination can confirm a diagnosis.

Terms to know

Urticaria: Raised, itchy welts on the skin, also called hives. Chronic urticaria lasts longer than six weeks.
Hives: Raised, itchy welts on the skin that come and go, also called urticaria.
Angioedema: Swelling in the deeper layers of the skin, often around the eyes, lips or throat. Swelling of the throat or tongue is an emergency.
Patch test: A test in which small amounts of possible allergens are applied to the skin to find the cause of contact allergy. Also used informally for trying a new product on a small area first.
Post-inflammatory hyperpigmentation: Dark marks left behind after skin inflammation or injury, such as acne, eczema or a burn. It is more common and lasts longer in darker skin.
Topical corticosteroid: An anti-inflammatory medicine applied to the skin. Effective when prescribed, but misuse, especially in mixed fairness creams, can cause serious side effects.

Full glossary

Read the guides

Full, referenced articles on drug rash and medicine allergy written for Indian skin, with answers to common questions.

Skin Conditions8 min read

Skin Rash From Medicines (Drug Allergy): When It Is an Emergency

A rash after a new medicine is an emergency if it blisters or peels, affects the mouth or eyes, or comes with fever, face swelling or breathing trouble.

Updated 27 October 2026

Skin Conditions7 min read

When to See a Dermatologist Urgently: Skin Red Flags

Seek emergency care for a blistering rash after a new medicine, a rash with fever that does not fade under a glass, or face swelling with breathing trouble.

Updated 27 October 2026

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This page is a short summary for general education and does not replace a consultation with a qualified dermatologist. Do not start, stop or change any medicine based on this page. Read the full medical disclaimer.