Skin Bumps: What They Are and What to Do

Common types of skin bumps

Itchy bumps on the skin

• Hives: welts that appear and disappear within hours. Triggers include infections, foods, medicines, heat and pressure, but often no cause is found.
• Insect bites: mosquitoes, fleas (often around the ankles) and bed bugs (rows of 3 on exposed skin at night).
• Scabies: intensely itchy small bumps and burrows between the fingers, on the wrists, waist and genitals, worse at night, often affecting several people in a household.
• Eczema and contact dermatitis: itchy, red, sometimes weeping bumps and patches.
• Heat rash: tiny itchy bumps in sweaty areas.
• Folliculitis from hot tubs: itchy bumps under swimsuit areas a day or two after using a poorly maintained hot tub.

Small, painless bumps

Keratosis pilaris, milia, molluscum, skin tags, seborrheic keratoses and small cysts are usually painless. They are harmless and treated only for appearance or irritation.

Painful bumps

• Boils and abscesses: red, hot, tender lumps filled with pus.
• Inflamed cysts: an epidermoid cyst that becomes red and sore.
• Hidradenitis suppurativa: recurring painful lumps in the armpits, groin and under the breasts.
• Shingles: painful clusters of blisters on one side of the body.
• Erythema nodosum: tender red lumps on the shins, linked to infections, pregnancy, medicines, sarcoidosis and inflammatory bowel disease.

When a skin bump could be cancer

Skin cancers are common, especially in fair-skinned and sun-exposed people. Know these warning signs:

• Basal cell carcinoma: a pearly or shiny bump, often with tiny blood vessels, that may bleed, crust and heal partially, then return. Usually on the face, ears and neck.
• Squamous cell carcinoma: a firm, scaly or crusted bump that grows over weeks and may be tender, often on sun-exposed skin.
• Melanoma: a mole or bump that is new or changing, or with ABCDE features: Asymmetry, irregular Border, multiple Colors, Diameter over 6 mm, or Evolving. Nodular melanoma is a firm, dark (sometimes pink) bump that grows quickly.
• Keratoacanthoma: a rapidly growing dome-shaped bump with a central crater.

How skin bumps are diagnosed

A doctor or dermatologist will ask when the bump appeared, whether it has changed, whether it itches or hurts, and about sun exposure, contacts and family history. Most bumps are diagnosed by looking, often with a dermatoscope. A scraping, swab, ultrasound or biopsy is used when the diagnosis is uncertain or cancer is possible.

Treatment

• Acne and folliculitis: benzoyl peroxide washes, topical retinoids, antibiotic creams or tablets.
• Keratosis pilaris: moisturizers with urea or lactic acid.
• Hives and bites: non-drowsy antihistamines and cool compresses.
• Scabies: permethrin cream or oral ivermectin for everyone in the household.
• Warts and molluscum: often clear on their own; freezing, salicylic acid or other treatments speed it up.
• Cysts, lipomas, skin tags and seborrheic keratoses: no treatment needed unless bothersome; removal by a minor procedure.
• Boils: warm compresses; larger abscesses need drainage.
• Skin cancers: removal by surgery or other treatments depending on type and stage.

Do not squeeze cysts or boils. It can push infection deeper and cause scarring.

Frequently asked questions

What are small bumps on my skin that don't itch?

Common causes include keratosis pilaris, milia, molluscum contagiosum, skin tags, seborrheic keratoses and small cysts. Most are harmless. See a doctor if a bump grows, bleeds, changes color, or does not heal.

What causes itchy bumps on the skin?

Itchy bumps are often hives, insect bites, scabies, eczema, contact dermatitis or heat rash. Bumps that are intensely itchy at night and affect others in your home suggest scabies, which needs treatment for the whole household.

When should I worry about a bump on my skin?

Get a bump checked if it bleeds, does not heal within 4 weeks, grows quickly, is a new or changing mole, is larger than 5 cm (2 inches), or is hard and fixed. A red, hot, painful lump with fever needs prompt care.

Are skin bumps contagious?

Some are. Warts, molluscum contagiosum, scabies, impetigo and some folliculitis can spread by skin contact. Acne, cysts, keratosis pilaris, skin tags and hives are not contagious.