Most brown spots with the exception of freckles are semi-permanent, lasting several years, or permanent without treatment. While they are rarely a medical concern, it can certainly be cosmetic concern. In the vast majority of cases, brown spots can be treated with skin brightening products (they may be marketed in various other ways such as skin lighteners, skin bleachers, etc) that can be purchased over the counter. Combined with proper sun protection, most brown spots are reversible.
First and foremost, we look at the active ingredients and their concentrations. There are several well known actives that effectively treat hyperpigmentation, and either remove the melanin, or inhibit melanin from being produced, lightening the skin.