Derma Clinic IndexColumnsWhy sun protection matters for melasma

Why sun protection matters for melasma

2026-11-08 · Updated 2026-11-08

Once you start melasma treatment, nearly every consultation brings up sun protection. You may wonder why sunscreen is stressed so much when you're being treated with laser or medication. Melasma tends to darken again in response to light, hormones and stimuli such as heat. So preventing it from darkening again matters as much as lightening it through treatment.

Melasma is pigment that reacts easily to light

Melasma is brown pigmentation that appears mainly on the cheeks, forehead and upper lip, usually symmetrically. It is known to arise when the skin's pigment cells overreact to stimuli such as UV and produce excess pigment, and pregnancy, hormone medications and genetic factors are also involved. It's common in women in their 30s and 40s but occurs in men too.

UV is the classic factor that directly stimulates pigment cells. Recently, research has been accumulating that not only UV but also visible light and heat contribute to darkening melasma. That's why melasma care emphasizes cutting exposure to sunlight as a whole, not just UV.

Skin becomes more sensitive during treatment

Melasma treatment uses topical brightening medication, oral medication, and laser or light treatments. While reducing pigment, these treatments can also irritate the skin. When irritated skin is exposed to sunlight, post-inflammatory pigmentation can develop and actually make it darker.

After laser treatment in particular, the skin barrier is temporarily weakened. Neglecting sun protection during this period can erode the gains from treatment or create new patches. Some topical brightening medications also make the skin more sensitive to light. It's fair to see sun protection as what safeguards the effect of treatment.

The same principle applies to treatment with oral or topical medication. If sunlight stimulates pigment cells again while the drug is suppressing pigment production, the effects cancel each other out and changes appear more slowly.

How to choose a sunscreen

SPF mainly indicates protection against UVB, which reddens the skin, and PA indicates protection against UVA, which penetrates deeper and affects pigment. If you have melasma, check both; for daily use, a product with at least SPF 30 and a high PA rating is generally recommended.

If you also want to account for visible light, tinted sunscreens are known to help, because pigments such as iron oxide block part of visible light. While your skin is sensitive, choose a gentle formula, and if it stings or turns red after you apply it, mention it at your appointment.

Apply generously and often

To get the protection shown on the label, sunscreen must be applied in larger amounts than most people think. Spreading it thinly greatly reduces the actual protection. A common recommendation is to apply it generously over the whole face and add another layer to the cheeks and forehead where melasma is.

Sweating or wiping your face removes sunscreen, so reapply every two to three hours outdoors. Considerable UV reaches the ground even on cloudy days, and UVA comes through windows indoors. That's why the habit of applying it every morning, whatever the weather, is needed.

If reapplying over makeup is difficult, you can top up with a cushion compact or powder that has sun protection. However, these products alone tend to deliver too little, so use them to supplement your morning sunscreen rather than replace it.

Sunscreen alone isn't enough

Physically blocking light with a hat, parasol or sunglasses at the same time increases the effect. It's also good to cut down on going out in strong midday sun and on situations that heat up the face, such as saunas or hot cooking environments.

Melasma easily darkens again even after treatment, which is why sun protection and care must continue after treatment ends. If the color deepens again after a change of season or living environment, it's better to see a doctor before it goes too far and adjust your care.

Some pigment disorders look like melasma but have different causes. Freckles, seborrheic keratoses and post-inflammatory pigmentation are treated differently, so alongside sun protection, the first step is an accurate diagnosis of what your pigment actually is.

Frequently asked questions

Do I need sunscreen if I stay indoors?

Yes, if you spend long periods by a window or in a sunny room. UVA passes through glass, and window light also contains visible light. Far from windows, one morning application may suffice; reapply when going out.

Is a higher SPF better for melasma?

Higher SPF gives more protection, but applying enough, often, matters more. Even high-SPF products lose much of their effect if applied thinly or not reapplied. With melasma, check PA too and pick one your skin tolerates daily.

When can I start using sunscreen after laser treatment?

Follow the timing your clinic gives; after gentle lasers, the same or next day is common. Gentle formulas may be advised right after treatment. Areas with scabs or wounds may need different care, so follow the instructions you received.