Sunlight helps your body produce vitamin D and it regulates your circadian rhythm, or body clock. Certain health conditions, however, can leave you with unpleasant reactions after you go out in the sun. Protecting your skin from sunlight may help prevent outbreaks of red skin bumps and related symptoms, and medications can help you manage outbreaks that do occur. If your skin bumps result in open sores or severe itching that disrupts your daily activities, consult a health care provider.

Medical Conditions

Two different conditions can cause red bumps on your skin after sun exposure. Bumps related to polymorphous light eruption may appear when you first go out in the sun after winter or expose a body part to sun when it hasn't had exposure in some time. The bumps may or may not reoccur the next time you go out in the sun.Another condition, solar urticaria, is a rare allergic reaction to sunlight. Even brief sun exposure of less than 30 minutes can trigger a reaction.


Polymorphous light eruption leaves small, closely gathered red skin bumps along with a red, itchy, burning rash. Symptoms most often occur several hours after sun exposure and typically appear on the chest and lower arms and legs, but not the face. Severe cases may cause chills, headache and nausea. Solar urticaria leaves an itchy rash with hives, or bumps, that may be swollen or red. This occurs on areas not normally exposed to sunlight. The condition usually doesn't affect your hands or face. If the outbreak covers a large area, you may experience light-headedness, headache, nausea and vomiting.

Risk Factors

Polymorphous light eruption occurs most often in Native Americans of North, Central and South American origin, note experts from the American Osteopathic College of Dermatology. Fair-skinned women younger than 30 are particularly vulnerable. Children and adults of any age or either gender can develop solar urticaria, but the condition most commonly appears when you're around age 35.


Mild- to moderate-strength topical steroids can help treat an outbreak of polymorphous light eruption. For more severe outbreaks, you may need oral steroids. If you have solar urticaria, shielding your skin from the sun should help clear up the rash within hours, advise New Zealand Dermatological Society experts. Oral antihistamines may also help reduce red bumps and itching.


Protecting your skin from sunlight may prevent both polymorphous light eruption and solar urticaria. Avoid the sun from 11 a.m. to 3 p.m. and when you do go out, apply titanium-based sunscreens of SPF 30 or higher. Phototherapy is another option for potentially preventing outbreaks of these conditions. With this therapy, a dermatologist desensitizes your skin to the sun using repeated controlled exposure to UV radiation. In some cases, antimalarial medications may help polymorphous light eruption, notes the American Osteopathic College of Dermatology.