White spots within a sunburn are commonly due to a yeast named tinea versicolor. The yeast lives in the pores of the skin.
How it Happens
According to the Mayo Clinic, under certain conditions tinea versicolor becomes overgrown. These conditions include hot, humid weather, excessive sweating, oily skin or hormonal changes. Under such conditions, growth of the yeast accelerates and causes the white, scaly spots.
Why the Spots
Tinea versicolor blocks the skin from tanning in places where there is an overgrowth of the yeast. The skin around the areas tans, leaving the infected area appearing lighter or white in color.
Over-the-counter antifungal lotion, cream or ointment is suggested for home treatment. The Mayo Clinic lists selenium sulfide shampoo (Selsun Blue), miconazole (Micatin), clotrimazole (Lotrimin) and terbinafine (Lamisil). Additionally, wearing loose-fitting clothing and not adding oily products to the infected area will assist in preventing an overgrowth of the yeast.
When to See a Doctor
Treating the condition does not cause immediate an immediate reversal of the spots. The white spots often take weeks to fade. If the condition does not improve with home treatment, it is best to seek medical advice.
The Mayo Clinic also points out there are other skin conditions that mimic tinea versicolor. The most common of which is vitiligo, a condition that although is not harmful also causes discoloration of the skin.