What Is This Bump? Common Skin Bumps and Rashes

Milia are tiny, hard white bumps, often around the eyes, caused by trapped keratin. Skin tags are soft, skin-coloured growths in folds like the neck and underarms. Warts are rough bumps caused by a virus, and calluses are thickened skin from pressure. Seborrheic keratoses are waxy, stuck-on-looking growths that become common with age.

Most of these are harmless and can be left alone or removed for cosmetic reasons. Avoid squeezing, cutting, picking or using at-home freezing kits, which can cause infection and scarring and may hide something that should be examined.

A dermatologist can usually tell what a bump is by looking at it, and can remove it safely when needed.

Soft, movable lumps under the skin are most often cysts or lipomas, which are harmless collections of skin protein or fat. Cysts can become inflamed or infected, especially if they are squeezed.

Red, tender bumps around hair follicles can come from folliculitis, ingrown hairs or irritation after shaving, waxing or laser hair removal. Hair can also become trapped in the skin between the fingers or in other folds, causing recurring inflamed bumps.

Any lump that is hard, fixed in place, growing quickly or painful should be examined.

Keratosis pilaris causes small, rough bumps on the upper arms, thighs and cheeks when keratin plugs the hair follicles. It is common and harmless. Moisturizers with urea, lactic acid or salicylic acid smooth the skin, though the bumps tend to return if you stop.

Stretch marks form when skin stretches quickly, such as during growth spurts, pregnancy or weight change. New marks are red or purple and respond best to treatment. Older, silvery marks are harder to change, but in-clinic treatments such as lasers and microneedling can improve them.

Most creams and oils marketed for stretch marks have limited evidence, though keeping the skin moisturized can help with itch.

Many rashes look alike, and the right treatment depends on the cause. Dyshidrotic eczema causes small, itchy blisters on the hands and feet. Seborrheic dermatitis causes greasy, flaky patches around the nose, eyebrows and scalp. Cold sores are caused by a virus and can be triggered by sun exposure and stress.

Some rashes mimic others. A rash around the mouth can look like a cold sore or seborrheic dermatitis, and each needs a different treatment. Using the wrong cream, especially a strong steroid on the face, can make some rashes worse.

Gentle skin care, avoiding known triggers and protecting the skin from the sun help many rashes. Persistent, spreading or painful rashes should be seen by a doctor.