Why do acne marks look darker after time outside?

Why does sunlight affect an old acne mark?

Acne inflammation stimulates cells to make more melanin, the pigment that gives skin its colour. Pigment can remain where the pimple healed, and ultraviolet rays from sunlight can make that patch darker. Acne marks can develop even after mild acne without much visible inflammation. Visible light also plays a role in acne related pigmentation, so UV exposure is not the whole explanation.34

Is a dark mark the same as an acne scar?

A flat dark mark is a colour change, not automatically a scar, even if the two get filed under the same complaint. True acne scars involve changes in the skin's structure, such as dents or raised tissue. Pigmentation and scarring can occur together. Red marks after acne are another type of colour change, called postinflammatory erythema, and are linked to changes in small blood vessels during healing. The sunlight and pigment explanation applies most directly to brown or dark marks, rather than every mark acne leaves.5

How can you stop marks getting darker outside?

Sun protection is part of managing dark marks, not an optional extra reserved for days with a beach in the itinerary. The aim is to minimise further darkening while the existing pigmentation improves.1

1. 1Choose a broad spectrum sunscreen, which protects against both UVA and UVB. SPF 30 or higher is general guidance for hyperpigmentation; SPF 50 or higher is the more specific guidance for exposed postinflammatory dark marks.
2. 2Apply sunscreen daily to exposed skin with dark marks. Make sun protection a regular part of your routine rather than waiting for the marks to darken.
3. 3Before going outside, add a hat and protective clothing. Limit time in direct sun rather than relying only on sunscreen.
4. 4Keep treating active acne as needed and avoid picking pimples. Addressing new breakouts matters alongside protecting the marks already present.

Who is more likely to get lingering dark marks?

Postinflammatory pigmentation can affect anyone, but it is more common in darker skin tones, where the colour tends to be more intense and last longer. Some medicines can also darken existing postinflammatory pigmentation. If you take medicines and the colour change is new or worsening, include them when discussing the marks with a clinician.14

How long will the marks take to fade?

Acne related colour changes often improve with time, but fading can take months or longer. Some acne pigmentation persists for years. Sunscreen helps prevent additional darkening; fading an existing mark is a separate process. Treatments for pigmentation can also take months to show improvement. Treating active acne matters as well as fading existing marks, because clearing the backlog is less useful while new entries keep arriving.3457

What if you have recently had scar treatment?

After acne scar treatment, skin can be sensitive and sunlight can darken the treated area. Follow your dermatologist's individual aftercare instructions. Typical care includes daily broad spectrum, water resistant SPF 30 or higher, applied 15 minutes before going outdoors, even for a brief trip. Avoid tanning and excessive daytime outdoor exposure, generally for 6 to 8 weeks, including cloudy or cool days. Peels, lasers and intense pulsed light can also worsen pigmentation by injuring the skin, so they are not an automatic fix for a dark mark.16

When should you get the marks checked?

Simple hyperpigmentation does not cause pain or itching. See a clinician if the area is red, hot, itchy, painful, bleeding or leaking fluid or pus. A dermatologist can also assess persistent marks and help choose a treatment suited to the pigmentation and any remaining acne.34