Skin lesions are areas of skin that look different from the surrounding area. They are often bumps or patches, and many issues can cause them.

The American Society for Dermatologic Surgery describe a skin lesion as an abnormal lump, bump, ulcer, sore, or colored area of the skin.

Most skin lesions are harmless, but some can be warnings of skin cancer.

This article will look at the most common types of skin lesions and offer advice about when to see a doctor.

Some common skin lesions and their treatments include:

Acne

Acne can appear as whiteheads, blackheads, pimples, or cysts. It can be harmless for some, but for others it can lead to scarring or low self-esteem.

Acne develops when the pores in the skin are clogged with dead skin cells and the skin’s natural oil, called sebum. Bacteria can also get into the clogged pore, inflaming the lesions.

People with mild acne may find over-the-counter (OTC) products that contain benzoyl peroxide or salicylic acid to be effective. These products usually produce any results in 4–8 weeks.

If acne is more severe or if OTC products do not work, a person should see a doctor, such as a dermatologist.

Learn more about acne here.

Eczema

Eczema is common and often appears as itchy, red patches of skin. These can form anywhere on the body.

Experts do not know what causes eczema, but it is not contagious.

It is a chronic condition, meaning that there is no cure, but medications and lifestyle changes can manage the symptoms.

The National Eczema Association recommend that people with eczema:

  • avoid anything that seems to make it worse
  • bathe and moisturize every day
  • use the medications recommended or prescribed by their doctors

Learn more about eczema here.

Cold sores

The herpes simplex virus causes a contagious infection. A person may only realize that they have it when they notice cold sores — which look like blisters — forming on or around their lips. The sores may be painful or tingly.

Cold sores tend to reappear from time to time. Stress and exposure to sunlight are among the various factors that can trigger an outbreak of the sores.

Cold sores usually go away on their own in a few weeks.

Some people use OTC creams that contain acyclovir to ease the symptoms and speed the healing process.

However, topical antivirals like these are not always effective. A person may be more likely to see results if they use prescription antiviral medication.

Learn more about cold sores here.

Blisters

When the skin is injured, a watery liquid called serum leaks into the damaged area from the surrounding tissue. This can form a bubble in the skin called a blister.

Burns, rubbing, infections, and allergies are the most common causes of blisters.

These lesions usually go away on their own — and popping or bursting them increases the risk of infection.

Learn more about blisters here.

Hives

Allergic reactions can cause hives, which look like a red, bumpy, itchy rash. Hives usually go away on their own.

If anyone suspects a serious allergic reaction, they should call 911 or otherwise contact emergency services. The warning signs include:

Learn more about hives here.

Impetigo

An infection of Staphylococcus or Streptococcus bacteria — known colloquially as staph or strep — causes impetigo.

Impetigo is a skin infection that forms red sores surrounded by red skin. The lesions fill with pus and become pimples, which then break open and crust over.

Impetigo is contagious, and it spreads easily. Doctors treat it with antibiotics.

Learn more about impetigo here.

Moles

Moles are circular or oblong patches that are darker than surrounding skin. The three main types of mole are:

  • Congenital: A person is a born with this type of mole, which may be of any size and on any part of the body.
  • Common: Most adults have 10–40 of these typically harmless growths, which tend to appear above the waist, in areas exposed to the sun.
  • Atypical: The skin cancer melanoma can form in atypical moles, which are usually larger than a quarter of an inch in diameter, not round, and more than one color.

People who have atypical moles should monitor them closely, as they can turn into skin cancer. Check for differences in the way that they look or feel and speak to a doctor about any changes.

Learn more about moles here.

Actinic keratosis

Actinic keratosis can develop on skin that has been damaged by the sun. It looks like flesh-colored, brown, pink, or red crusty bumps.

People with actinic keratosis have a high risk of developing skin cancer.

Doctors may recommend surgery, creams, or light therapy as treatments.

Learn more about actinic keratosis here.

Psoriasis

Psoriasis usually forms patches of itchy or scaly skin. The patches tend to appear on the elbows, knees, or scalp, but they can develop on any part of the body.

Scientists do not yet know exactly what causes psoriasis. However, it is an autoimmune condition — it results from a problem with the immune system. There is no cure, but several treatments are available.

OTC creams and ointments can help some people, while others need prescription medication.

Learn more about psoriasis here.

Ringworm

Fungus causes ringworm, a skin infection that can form a circular rash. It can appear on any part of the body, and the rash is usually surrounded by itchy, red, scaly skin and hair loss.

People sometimes call ringworm on the feet athlete’s foot or ringworm on the groin jock itch.

OTC creams, lotions, and powders can treat the infection.

The name for ringworm on the scalp is tinea capitis, and it usually requires prescription antifungal medication. Treatment can take 1–3 months.

Learn more about ringworm here.

If OTC products do not resolve acne, eczema, or psoriasis, a person should contact a doctor, who may prescribe medication in the forms of creams, lotions, or pills.

There are no OTC treatments for impetigo. Anyone who thinks that they or their child has the infection should speak to a doctor.

Ringworm on the scalp requires medical attention. Anyone who suspects that they have this should see a doctor, who can prescribe antifungal medication.

Anyone who notices new moles or changes in existing moles should contact a doctor, who may screen for skin cancer. The same is true for people who have actinic keratosis.

A range of health issues and factors such as shoes or clothes rubbing against the skin can cause lesions.

Some of these lesions, including cold sores and blisters, usually go away on their own within a few weeks. Others, such as eczema and psoriasis, are long-term conditions that need ongoing treatment.

In many cases, doctors can treat lesions that may become cancerous. Anyone with concerns about skin cancer should contact a healthcare provider.