You thought it was just a freckle, but now there's a brown patch spreading above your upper lip. It could very well be melasma.

Melasma is a skin pigmentation disorder that, while not dangerous to your health, can be a bothersome cosmetic issue. Dermatologists say once you have it, you're likely to have it for life. The good news, however, is that there are options for mitigating the problem before it gets worse.

To understand what the condition is and what you can do about it, we spoke with dermatologists Dr. Katie Beleznay in Vancouver, and Dr. Lisa Kellett and Dr. Julia Carroll in Toronto.

What is melasma?

Melasma is a hyper-pigmentation skin disorder that results in brown patches on the face, often on the cheeks, bridge of the nose, forehead, chin and above the upper lip. It's not known exactly what causes melasma but dermatologists believe it's linked to some combination of hormones and exposure to sun, heat or light. When those factors come into play, they stimulate the skin's melanocyte cells, which then begin producing increased melanin, resulting in brown patches.

It's sometimes called the "mask of pregnancy" because pregnant women are more prone to it.

Who can get it?

Anyone can get melasma but it's most common in women between the ages of 20 and 60. Dermatologists say women who are pregnant or on the birth control pill are more prone to it, as are people with darker skin.

What should you do if you notice skin discolouration?

Go see a dermatologist or a general practitioner. The skin discolouration could be due to any number of things, including age spots, melasma or skin cancer. Obviously it's critical to be diagnosed as early as possible in the case of skin cancer, but an early diagnosis of melasma can make treatment more effective.

What are the treatment options?

Dermatologists say the best treatment is sun avoidance and daily application of sunscreen. Beleznay goes so far as to recommend that patients put on sunscreen before walking past a window on sunny days — being of the mind that even small doses of sun exposure is enough to worsen pigmentation.

Other options include topical treatments made from hydroquinone, tretinoin, azelaic acid or kojic acid. Some dermatologists raise concerns about the use of hydroquinone, saying there isn't enough information available about what it does to the skin, and that it may darken it. Others, including Carroll, say they would still recommend it and that misconceptions about hydroquinone are based on past examples of improper use or dosage.

Lasers are also a possible treatment option, but dermatologists are wary.

"There are certain laser procedures that can make it worse, for sure, especially in the hands of someone who's not trained," said Carroll. "They just think pigmentation is pigmentation and they're treating it like a freckle. That can actually damage the skin and it can make it worse."

She notes there is one laser procedure, called Halo, that may effectively treat melasma, fading spots within two to four weeks, but she recommends only receiving laser treatment from a qualified dermatologist.

As for discontinuing birth control, Beleznay said she might discuss that option with a patient, if it's clear the hormones are triggering melasma.

Does it ever go away?

For many people, treating melasma will be a lifelong commitment.

"Once you stimulate melanocyte (cells), they have a memory," said Kellett. "It's almost like you're even more sensitive to future stimulants … you will have almost a lower threshold."

But there is the possibility spots will fade after pregnancy or after discontinuing the birth control pill. Dermatologists also say a combination of topical treatment application and dedicated sun avoidance can keep the effects of melasma at bay.

"I have seen people totally clear it," said Carroll. "I still remind them that they have to keep their guard up."

Katrina Clarke is a Toronto-based journalist who writes about relationships, health, technology and social trends. Find her on Twitter at @KatrinaAClarke.