Melasma is darkening of the skin in response to sun exposure. This often happens when someone is taking hormones or is pregnant. But some people inherit skin that is more likely to develop such dark patches from sun exposure.
The key is sun protection. Even a very limited time in the sun can result in melasma in people prone to it.
Over-the-counter or prescription bleaching creams can help. But sun exposure can quickly result in losing the ground gained in lightening the dark patches. Bleaching creams work slowly. But they help if they are applied as directed, and if skin is protected from the sun. Be sure to stop using the creams if you get irritated since irritation can also cause skin darkening.
There are other options to treat melisma. For example, intense pulsed light is a cosmetic, light-based treatment that targets skin pigment. Cosmetic peels may also help.
If your melasma persists, see your dermatologist. He or she can help you find the underlying cause. And guide you in cosmetic treatment options.