The answer so far
Dark spots and patches can have different causes, including healing after irritation, sun exposure and melasma. Natural differences in skin colour are normal. Understanding the cause matters because a cosmetic claim cannot diagnose a mark, and a changing or bleeding spot needs a professional assessment.12
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Why can a mark appear?
Skin produces melanin, a pigment that contributes to its colour. A darker mark can appear after a spot, eczema, a burn or other irritation settles; it is often called post-inflammatory hyperpigmentation. Melasma is a different pattern of darker patches and can be influenced by sunlight and hormonal changes. These are examples, not a way to diagnose a particular mark from a description. Skin of every natural colour is normal.1
- After irritationAcne, a burn or another injury can leave a darker mark.
- PatchesMelasma is one possible cause; sunlight can make it more noticeable.
- Protect and investigateSun protection and finding the cause are useful starting points.
- Changing spotA growing, bleeding, itching or changing spot needs clinical assessment.
Why does the cause matter?
If a product irritates skin or acne keeps recurring, new marks may appear even as older ones fade. Identifying and addressing the cause can matter as much as the product used on a mark. Some changes fade gradually; timing varies with the cause and depth. A healthcare professional can help distinguish a persistent concern from another condition.1
What can sun protection do?
Sunlight can make some pigmentation more noticeable. The American Academy of Dermatology advises sun protection as part of managing dark spots: seek shade, use protective clothing and choose broad-spectrum sunscreen. Its guidance on dark spots also discusses tinted sunscreen containing iron oxide for visible-light protection. A cosmetic or supplement is not a substitute for sunscreen.1
When should a spot be checked?
A spot or mole that is growing, changing, itching or bleeding should be assessed promptly by a qualified clinician. A cosmetic cannot tell you what a spot is; avoid covering up a concerning change as a substitute for getting it checked. Skin changes can have many causes, and an examination is the way to understand yours.2
How do I compare cosmetic claims?
Look for a study of the finished formulation and the particular result that matters to you: pigment measurement, appearance of a specific condition, or irritation. A short trial in healthy skin does not establish a treatment for every dark patch. For example, the glutathione skin studies examine different products and outcomes, while copper-peptide serums have a separate evidence base.31
Where do retinoids fit?
Retinoids are a family that includes certain cosmetic ingredients and prescription medicines; the products, uses and precautions are not interchangeable. They can irritate skin, and pregnancy or pregnancy planning changes the question for some products. Read vitamin A, retinol and skin medicines and discuss an individual concern with a pharmacist or clinician.1
Sources, kept close.
Selected supporting sources; this is not a complete literature review.
- How to fade dark spots in darker skin tonesAmerican Academy of Dermatology · Professional association patient guidance
- Moles: OverviewAmerican Academy of Dermatology · Professional association patient guidance
- Skin-whitening and skin-condition-improving effects of topical oxidized glutathioneClinical, Cosmetic and Investigational Dermatology / PMC · Randomised split-face trial