What should you know about one itchy bump on your skin?

A single bump can follow an insect bite, contact with a new product, friction or an inflamed hair follicle. Eczema, psoriasis, lichen planus or hives can also produce itchy raised areas, although these conditions often have additional features or more than one lesion. Scabies is more suggestive when itching is intense at night or other household members itch too.

Look for scale, a central punctum, blisters, pus, a ring shape, spreading redness or new bumps elsewhere. A description and photograph can help a clinician, but scratching may change the appearance and make the cause harder to identify.

Wash gently, use a cool compress and avoid scratching. Keep nails short and stop any new soap, cosmetic, adhesive or plant exposure that may have touched the area. Do not squeeze a bump or apply leftover steroid, antibiotic or antifungal cream without advice, because the wrong product can irritate skin or mask infection.

Monitor its size, colour, pain and nearby lesions. Arrange a routine review if it persists, recurs, spreads or interferes with sleep, work or daily activity.

Seek urgent help for trouble breathing, swelling of the lips or tongue, faintness or rapidly widespread hives. Obtain prompt medical advice for severe pain, warmth with spreading redness, pus, fever, a blistering reaction, or a bump near the eye.

Ask whether the lesion resembles a bite, dermatitis, follicle inflammation or another condition, whether a medicine is needed, and which changes should prompt a faster follow-up.