Uneven Skin Tone: Causes of Blotchy Skin

What causes uneven skin tone

Skin color comes mainly from melanin, a pigment made by cells called melanocytes, plus blood flow in the skin. Uneven tone happens when melanin is made in excess in some areas (hyperpigmentation), lost in others (hypopigmentation), or when blood vessels widen. This page helps you work out what is causing your patches. For ways to even out your skin, see the treatment guide to uneven skin tone.

Darker patches

Sun damage and sun spots

Years of UV exposure cause flat brown spots on the face, hands, shoulders and arms, called age spots or solar lentigines. They are common after 40 and are a sign of sun damage, not age itself. Sun also deepens freckles and causes a mottled, leathery look.

Melasma

Melasma causes symmetrical, blotchy brown or gray-brown patches on the cheeks, forehead, upper lip and nose. It is much more common in women, especially during pregnancy (the "mask of pregnancy") or on birth control pills, and in people with medium to darker skin. Sun and heat make it worse.

Post-inflammatory hyperpigmentation

Any inflammation, including acne, eczema, insect bites, burns, cuts and harsh cosmetic treatments, can leave dark marks behind. Post-inflammatory hyperpigmentation is especially common and long-lasting in darker skin. Marks fade slowly over months.

Other darker patches

• Acanthosis nigricans: dark, velvety, thickened skin in the neck, armpits and groin, linked to insulin resistance, obesity, diabetes and some hormone conditions.
• Medicines: minocycline, some chemotherapy, antimalarials and amiodarone can cause gray-blue or brown discoloration.
• Hormonal and medical conditions: Addison's disease causes widespread darkening, especially in creases and scars.

Lighter patches

• Vitiligo: milk-white, sharply defined patches where melanocytes have been destroyed by the immune system. Common on the face, hands, around the mouth and eyes, and genitals.
• Tinea versicolor: a common yeast overgrowth causing lighter, darker or pink patches with fine scale on the chest, back and shoulders, more noticeable after a tan.
• Pityriasis alba: pale, slightly scaly patches on the face of children with dry skin or eczema.
• Post-inflammatory hypopigmentation: lighter skin after eczema, psoriasis or a burn.

Redness and mottling

• Rosacea: persistent central facial redness, flushing and visible blood vessels.
• Broken capillaries: small red lines on the nose and cheeks from sun, aging and rosacea.
• Livedo reticularis: a lacy, purple mottling of the legs, often from cold and harmless, but occasionally linked to blood vessel or clotting conditions.

Clues to the cause

When a patch could be skin cancer

Most uneven tone is cosmetic, but check spots with the ABCDE rule: Asymmetry, irregular Border, several Colors, Diameter over 6 mm, and Evolving (changing). A spot that differs from your others, grows, bleeds or does not heal needs a dermatologist. Lentigo maligna, a type of melanoma, can look like a large, irregular sun spot on the face of older adults.

How doctors find the cause

A doctor or dermatologist examines the patches, often with a magnifying light (dermatoscope) or a Wood's lamp (ultraviolet light), which makes vitiligo glow bright white and tinea versicolor glow yellow-green. A skin scraping confirms tinea versicolor. A biopsy is used for suspicious spots. Blood tests check for diabetes or hormone problems when acanthosis nigricans or widespread darkening are present.

Frequently asked questions

What causes uneven skin tone on the face?

The most common causes are sun damage, melasma, dark marks left after acne, and redness from rosacea. Hormones, pregnancy, birth control pills and some skincare reactions also contribute. Daily sunscreen is the single most important step for all of them.

Why is my skin suddenly blotchy?

Sudden blotchiness can come from flushing, heat, alcohol, an allergic reaction, irritation from a product, or a rash. Mottled, purple, blotchy skin with fever, cold hands and feet or confusion can be a sign of sepsis and needs emergency care.

What causes light patches on the skin?

Common causes are tinea versicolor (a yeast infection), vitiligo, pityriasis alba in children, and lightening after eczema or other inflammation. A doctor can tell them apart with a Wood's lamp and skin scraping, and each has a different treatment.

Is uneven skin tone a sign of a health problem?

Usually not. Most uneven tone is from sun, hormones or past inflammation. Some patterns do point to health issues: dark, velvety skin folds suggest insulin resistance, widespread darkening can signal Addison's disease, and spreading white patches suggest vitiligo.