A big bump on the skin: what to check and what to do

Its location, surface, firmness, colour, onset and accompanying symptoms provide more useful clues than size alone. Do not squeeze an unexplained lump; protect it from rubbing and monitor for rapid change, spreading redness or systemic illness.

A tender red bump centred on a hair can fit folliculitis, while a smooth lump beneath the surface can be a cyst. An itchy raised area appearing suddenly may follow a bite, contact reaction or hive. Heat rash typically presents with clusters of small prickly bumps in sweaty, covered areas rather than a single deep mass. Milia and keratosis pilaris also tend to cause smaller, characteristic bumps.

A photograph taken in consistent lighting can show whether the border, colour or height changes. Note whether the lump moves under the skin, has a central opening, releases fluid, or appeared after a new medicine, skin product, injury or period of friction.

Leave the surface intact and wash with a mild cleanser. A cool compress can soothe itch or irritation; a warm compress may feel more comfortable for a tender follicular bump. Avoid strong acids, harsh scrubs and several new remedies at once, as irritation can alter the appearance and make the cause harder to judge.

Treatment should match the diagnosis. Antihistamine treatment may be considered for an allergic or hive-like process, while cryotherapy is reserved for selected lesions identified by a clinician. Neither is a general treatment for every unexplained lump, and a suspected abscess may need a different approach.

Seek urgent help for trouble breathing, swelling of the lips or tongue, faintness, or a rapidly spreading rash. Prompt clinical care is also appropriate when the bump becomes very painful or hot, redness expands, red streaks develop, drainage smells unpleasant, or feverishness and chills occur.

Book a routine skin assessment for a lump that keeps enlarging, remains without an obvious explanation, repeatedly breaks down, bleeds spontaneously, changes colour or texture, or returns after seeming to heal. This advice is based on the behaviour of the bump, not on an assumption about which condition is common.

Tell the clinician when the bump began, how quickly it changed, whether it hurts or itches, and what came into contact with that skin. Ask whether it is arising in the surface, a hair follicle or deeper tissue; whether examination alone is enough; and what changes should trigger a faster follow-up. Bring a list of medicines and recent skin treatments if an allergic reaction is possible.