What Causes White Spots on Skin and How Can You Treat Them?

If you're over age 40 and spend time outdoors, you may have noticed the appearance of small white dots on your skin. These spots are typically more noticeable during warm weather months when the contrast is greater between them and the surrounding skin.

So what are they?

The medical term for this condition is Idiopathic Guttate Hypomelanosis (IGH), and while the name may make it sound alarming, the condition is benign. The exact cause of IGH isn't fully known, hence the word "idiopathic" in its name, which means "unknown cause." Researchers have, however, identified a short list of factors that contribute to the development of IGH, including age (87% of those over age 40 have spots on the skin characteristic of IGH), genetics (if your parents have IGH spots, you are likely to, as well), and UV exposure.

We talk often on this blog about hyperpigmentation, which is the appearance of darkened spots on our skin due to UV exposure (hyper=excessive, pigmentation=skin coloring). White spots on the skin are hypopigmentated (hypo=reduced). While opposite in appearance, both hyper- and hypo-pigmentation primarily occurs on areas of the skin that are most exposed to the sun, including arms, legs and hands. Additionally, the severity of the condition typically increases in relation to cumulative sun exposure.


Despite the fact that idiopathic guttate hypomelanosis doesn't present a health risk, the white spots synonymous with the condition can present a cosmetic concern for some individuals. For that reason, doctors often see patients who want to know how they can resolve the spots.

Considering that the white spots associated with IGH are void of melanin (skin pigment), a topical treatment is limited in its ability to return color to the skin and its therefore important to have realistic expectations for treatment. Doctors often prescribe tretinoin (a retinoid) for daily application to white spots. In one study, after four months of consistent application, patients saw a partial restoration of skin pigment.

Other treatments for IGH include:

  • A series of phenol peels (a deep type of chemical peel). After two peels, 64% of subjects in a study showed some degree of repigmentation to areas of IGH.
  • Cryotherapy, a treatment that uses liquid nitrogen to freeze areas of skin, can be used to remove white spots associated with IGH. One researcher documented that 90% of subjects saw pigment improvement using this therapy.
  • Laser treatment has proven successful in improving pigmentation in IGH spots. One study compared the results of two types of lasers - fractional CO2 and Er:YAG - against tretinoin. After two treatments, both types of laser showed superior results to tretinoin, with no significant difference between the two laser types.


While there are viable treatments for white spots on skin, with new research pointing to even more therapies in the future, prevention remains the best medicine. Sunscreen is beneficial in helping to prevent, or at least minimize, the development of white spots on the skin, just as it is helpful in minimizing the potential for photoaging. Simply applying sunscreen in the morning isn't enough. It's vital that you use enough sunscreen and re-apply throughout the day to all exposed areas of skin. Additionally, be sure to seek shade whenever possible and wear a hat along with UV-protective clothing.