Many people, especially women, develop brown patches on their faces.
They often show up on the cheeks, and sometimes on the forehead, nose and upper lip.
This skin discolouration, known as melasma, can be distressing, as it can make one look older. This can affect a person's self-confidence, said Dr Calvin Chan of Aesthetic and Laser Clinic at Wheelock Place.
On the bright side, it is not life-threatening.
About nine in 10 sufferers are women. Among them, 10 per cent to 15 per cent are pregnant or perimenopausal - the transition phase towards menopause - while up to 25 per cent are using oral contraceptives. This is because hormonal changes are linked to melasma.
Some other common triggers include sun exposure, cosmetics usage and a genetic predisposition, said Dr Chan.
"If your mother has melasma, you are more likely to have it as well."
It is also more common in darker-skinned people, he added.
Due to its link to hormonal changes, the condition tends to affect women of reproductive age.
"For example, women in their late 20s to early 30s will start to see melasma form," said Dr Chan.
"It also affects men who are genetically predisposed to it, and who spend a lot of time in the sun."
There are three kinds of melasma - epidermal, dermal and mixed.
The first is the most superficial, said Dr Chan, and therefore the easiest to treat.
The second type affects the deeper mid-layer of skin, and can be more stubborn.
Mixed melasma, as the name suggests, has elements of the other two types.
He said "there is no real cure" for the condition and that chances of recurrence are high.
But it helps to steer clear of the triggers. One can choose to stop taking contraceptive pills, for instance.
Otherwise, it may be wise to take sun protection measures, given that sun exposure is a major trigger. These include:
- Using a broad-spectrum UVA and UVB sunscreen with a sun protection factor (SPF) of 30.
- Re-applying the sunscreen every two hours.
- Avoiding the sun from 10am to 4pm, when the rays are at their strongest.
- Wearing a wide-brimmed hat and protective clothing; and
- Trying not to use harsh skincare products.
The severity of melasma would be judged based on the size and darkness of the patches, said Dr Chan.
"Stubborn and persistent melasma patches will generally not go away on their own," he said. "But doctors will be able to manage the condition to dramatically improve its appearance temporarily, or while treatment is ongoing."
This can be done with the help of procedures like chemical peels and microdermabrasion, where superficial layers of the skin are removed to allow active ingredients and lightening compounds to penetrate the deeper layers of the skin.
Intense pulsed light and laser treatments are effective too, though they may sometimes make things worse, said Dr Chan.
Doctors may prescribe topical treatments containing ingredients like tretinoin, hydroquinone and fluocinolone acetonide. These are applied on the affected areas.
The above treatments can be used in combination as well. As for over-the-counter skin products, look out for ingredients like arbutin, vitamin C and kojic acid, he added.
Poon Chian Hui