“Pigmentation” gets used as a catch-all term, but it covers a few genuinely different things, and the type you're dealing with changes what's worth trying. Here's how to tell them apart, in plain terms.

Post-inflammatory hyperpigmentation (PIH)

PIH shows up after something has disturbed the skin: a spot, a scratch, an insect bite, or a reaction to a product that was too strong. It usually appears as a flat mark roughly the same shape and size as whatever caused it, and it can happen to any skin tone, though it tends to be more visible and slower to fade on deeper skin. This is the type most closely linked to irritation, which is why picking gentler actives matters as much as picking effective ones.

Melasma

Melasma tends to look different: symmetrical, often larger patches on the cheeks, forehead, upper lip, nose or chin. It's strongly linked to hormones, which is why it's sometimes called the ‘pregnancy mask’, and it's also triggered or worsened by UV exposure and, for some people, the contraceptive pill or hormone replacement therapy. According to the British Association of Dermatologists, melasma has no single cure, though its appearance can be managed, and it may fade naturally after pregnancy, only to return later if triggers reappear.

Sun spots (lentigines)

These are smaller, well-defined spots that build up gradually from years of cumulative sun exposure, most often appearing on areas that get regular sun such as the face, hands and shoulders, and becoming more common with age.

Why the distinction matters

Treating melasma like a sun spot, or PIH like melasma, often means using the wrong intensity of product for the wrong length of time, which risks the very irritation that makes pigmentation worse. If pigmentation appears suddenly, changes shape, or doesn't fit these patterns, it's worth having it looked at by a GP or dermatologist rather than guessing. The British Association of Dermatologists specifically recommends telling a doctor about any change to a mole or patch of skin, and any concerning changes can be referred through the NHS at no cost.

FAQs

Can I have more than one type of pigmentation at once?

Yes, it's common. Someone with melasma, for example, is statistically more likely to also develop post-inflammatory hyperpigmentation from acne, so it's worth treating each mark on its own merits rather than assuming one cause fits all.

Does pigmentation always need a dermatologist to diagnose?

Not always, but if marks appear suddenly, change shape, or don't fade as expected, it's worth getting them checked. Diagnosis is usually straightforward for a dermatologist, and can be done for free via NHS referral if your GP is concerned.

Which type of pigmentation is easiest to treat?

Post-inflammatory hyperpigmentation from a healed spot often responds fastest to consistent, gentle brightening care and sun protection, since there's no ongoing hormonal trigger. Melasma tends to be the most persistent because its underlying triggers are harder to remove entirely.

Research & further reading

•     British Association of Dermatologists — Melasma patient information leaflet: bad.org.uk/pils/melasma

•     British Skin Foundation — Melasma: britishskinfoundation.org.uk/conditions/melasma

Internal links to include

•     Links back to Pigmentation, decoded pillar

•     Links to Melasma after pregnancy post

•     Links to Brightening without the backlash post