Abnormally dark or light skin

Skin can become darker or lighter when the amount or distribution of pigment changes. The main skin pigment is melanin, which helps give skin, hair, and eyes their colour. Blood flow, inflammation, scarring, and changes within the body can also affect how skin looks.

A colour change may involve one small patch, several areas, or much of your body. It may develop gradually or appear after a rash, injury, infection, medicine, or sun exposure.

Many causes are harmless or treatable. However, a new or unexplained change sometimes needs medical assessment, especially when it is spreading or occurs with other symptoms.

A change in skin colour often causes no physical sensation. Depending on the cause, the area may also be itchy, dry, scaly, thick, sore, or sensitive.

Darker skin may look tan, brown, grey-brown, purple-brown, or nearly black. Lighter areas may be slightly faded or may have little to no visible pigment. Colour changes can be harder to recognise in some skin tones, particularly when inflammation looks brown, purple, or grey rather than red.

Notice whether the area:

• Has a clear or blurred edge
• Is smooth, scaly, raised, or thickened
• Appeared after a rash, burn, spot, or injury
• Changes with sun exposure
• Is growing or developing new colours
• Affects hair, the mouth, or the genitals

Paleness caused by reduced blood flow or anaemia is different from pigment loss. Anaemia means there are too few healthy red blood cells or too little haemoglobin, the substance that carries oxygen.

Sun exposure can darken exposed skin or make existing patches more noticeable. Freckles and sun-related spots may also become darker over time.

Inflammation or injury can leave skin darker or lighter after acne, eczema, insect bites, burns, cuts, or other irritation. This is called post-inflammatory pigment change. It may remain after the original problem has healed.

Melasma causes flat brown or grey-brown patches, often on the face. Hormonal changes and sunlight can contribute.

Tinea versicolor is an overgrowth of yeast that normally lives on the skin. It can cause lighter or darker scaly patches, usually on the chest, back, neck, or upper arms.

Vitiligo causes well-defined areas that lose pigment. It happens when the immune system mistakenly attacks pigment-making cells. The patches may slowly spread, remain stable, or change unpredictably.

Acanthosis nigricans causes darker, thicker, velvety skin, often around the neck, armpits, or groin. It may be associated with insulin resistance, meaning the body does not respond normally to insulin.

Less common causes include medicines, nutritional problems, inherited conditions, scarring, and hormone disorders. Addison’s disease, an uncommon adrenal gland disorder, can cause widespread darkening along with symptoms such as severe tiredness, weight loss, dizziness, nausea, or salt cravings.

A new or changing dark spot can occasionally be skin cancer. Changes in size, shape, colour, surface, or bleeding should be examined rather than identified from appearance alone.

Book a routine appointment if a colour change is unexplained, keeps spreading, lasts several weeks, or bothers you. Arrange an assessment sooner if a patch is painful, repeatedly itchy, thickening, bleeding, or changing quickly.

Seek same-day medical advice for new widespread darkening accompanied by severe weakness, vomiting, abdominal pain, dizziness, or faintness. Sudden paleness with marked weakness, a racing heartbeat, breathlessness, or ongoing bleeding also needs prompt assessment.

Call emergency services if the skin, lips, or tongue become blue or grey, especially with breathing difficulty, chest pain, confusion, severe drowsiness, or collapse. These signs may mean the body is not receiving enough oxygen and are not typical pigment changes.

A clinician will examine the colour, borders, texture, and distribution of the affected skin. They may ask when it began, whether it followed a rash or injury, and whether you have started any medicines or skin products.

A special ultraviolet lamp may help show pigment loss or certain infections. Gentle skin scrapings can be checked for fungus. Blood tests may be considered when symptoms suggest anaemia, thyroid disease, adrenal problems, or another condition affecting the whole body.

An unusual or changing area may need a skin biopsy. This involves removing a small sample under local anaesthetic for examination under a microscope.

Treatment depends on what is causing the colour change. Some patches need no medical treatment and fade gradually.

Protecting your skin from sunlight can prevent contrast from becoming more noticeable. Use shade, protective clothing, and broad-spectrum sunscreen. Avoid tanning to try to blend lighter patches because this can increase the contrast and damage your skin.

Use gentle skin products, especially if the area is dry or irritated. Avoid rubbing, picking, or repeatedly applying strong exfoliating products.

Depending on the diagnosis, treatment may include antifungal medicine, anti-inflammatory creams, light-based treatment, or medicines that reduce pigment production. These options are not suitable for every cause or body area.

Do not use household bleach, lemon juice, or unregulated skin-lightening products. Some products sold without reliable quality controls may contain mercury or strong steroids and can cause lasting skin damage. Cosmetic camouflage or self-tanning products may help cover some patches without changing the underlying condition.

Colour left after inflammation often fades slowly over months, although it can last longer. Fungal patches may take time to return to their usual colour even after the infection is treated.

Some conditions, including melasma and vitiligo, can improve, return, spread, or remain stable. Follow-up may be useful if the appearance changes or treatment irritates your skin.

Is a skin colour change contagious?

Pigment changes themselves are not contagious. Some infections that affect skin colour may spread between people, although tinea versicolor is generally linked to overgrowth of yeast already present on the skin.

Could a new dark patch be cancer?

Most dark patches are not cancer. However, a spot that is new, changing, irregular, sore, or bleeding should be checked. Appearance alone cannot confirm the cause.

Why does a healed rash leave a mark?

Inflammation can temporarily increase or reduce pigment production. The resulting mark may remain after itching, scaling, or redness has settled.

Will my normal colour return?

It depends on the cause and the depth of the pigment change. Some marks fade completely, while scars and certain pigment conditions may be long-lasting.