Sun rash is a type of photodermatosis, where exposure to sunlight causes a reaction on your skin. One common sun rash is called polymorphous light eruption (PMLE), sometimes also called a sun poisoning rash.

PMLE is a red, itchy rash that appears because of exposure to sunlight.

Many people incorrectly refer to PMLE as a sun allergy. In fact, as mentioned, PMLE is a type of photodermatosis. This refers to a sun-related skin disorder. It is one of the most common forms, occurring in around 10 to 20 percent of people.

Other kinds of sun rash can:

  • have hereditary causes
  • relate to the use of certain medications
  • have links to exposure to compounds in certain plants

We explain how to spot sun rash, what causes it, and how to manage symptoms once they develop.

Sun rash typically appears several hours or days after sun exposure. It can develop anywhere on the body that’s exposed to sunlight. Some kinds of sun rash occur on skin that’s usually covered in the fall and winter, such as your chest or arms.

Characteristics of the rash can vary between people depending on skin type, but they can include:

  • groups of small bumps or blisters
  • itchy red patches
  • areas of the skin that feel like they’re burning
  • raised or rough patches of skin

If a person also has a severe sunburn, they might also feel a fever or headache.

Some people who get sun rash live with a rare photodermatosis called solar urticaria (sun allergy hives). Folks with solar urticaria may feel the following symptoms alongside sun rash:

  • faintness
  • breathlessness
  • headache
  • other allergy symptoms

These symptoms will usually happen within a few minutes of sun exposure for people with solar urticaria.

Doctors have yet to work out exactly what causes sun rash.

UV radiation from the sun or artificial sources like sunlamps might cause reactions in some people with a sensitivity to this type of light. The resulting immune reaction triggers the rash.

Some risk factors for certain kinds of sun rash can include:

  • being assigned female at birth
  • having light skin
  • living in Northern regions, such as Scandinavia, Central Europe, and the United States
  • having a family history of sun rash
  • living in high altitude areas

If you experience a rash after being out in the sun, it’s important to speak with a doctor, such as a dermatologist (if you have access to one). They can rule out other conditions like contact dermatitis or lupus.

Your doctor can also examine the area to see what kind of sun-induced rash it might be. If you’ve never had a sun rash before and suddenly get one, call your doctor.

You should get immediate medical attention if your rash becomes widespread and painful or if you also have a fever. Sometimes, sun rashes can mimic other, more serious ailments, so it’s best to have a medical professional examine you.

Healthcare professionals do not always recommend treatment for sun rash. Most of the time, it can resolve without treatment in a few days. However, this depends on the specific rash and if there’s severe sun poisoning.

The following remedies can help you manage your comfort while the rash is visible:

  • Apply anti-itching creams. If your rash itches, an over-the-counter (OTC) anti-itch corticosteroid cream like hydrocortisone can be helpful. OTC oral antihistamines can also help.
  • Try cold compresses or a cool bath. These can also provide itch relief.
  • Avoid scratching at any blisters. If you have any blisters or if the rash is painful, don’t scratch or pop the blisters. This can lead to infection. You can cover the blisters with gauze to help protect them and take an OTC pain-relieving medication like ibuprofen (Advil, Motrin) or acetaminophen (Tylenol)
  • Use gentle moisturizers. As your skin starts to heal, you can use gentle moisturizers to relieve itching from dry or irritated skin.

These remedies aren’t effective for everyone. If the treatments don’t have the desired effect, you might need to reach out to a doctor. They can prescribe you a stronger anti-itch cream or oral medication to relieve symptoms.

For people who regularly take medication for another condition, a doctor can let you know if your sun rash is a side effect of the medication.

If your sun rash is due to an allergy, your doctor might prescribe allergy medication or corticosteroids to help address any symptoms you might be having. Sometimes, a physician will prescribe the antimalarial medication hydroxychloroquine, since it’s been shown to address symptoms of certain types of photodermatoses.

There are precautions you can take to minimize your risk of sun rash happening again:

  • Wear sunscreen. Apply sunscreen with an SPF of at least 30 about a half hour before going out into the sun, and reapply every 2 hours (sooner if you go swimming or are sweating a lot).
  • Protect your skin with long-sleeve shirts and a wide-brim hat. You might also want to think about wearing specially made clothes that contain sun protective factors.
  • Avoid the sun between 10 a.m. and 2 p.m., when the sun’s rays are most intense. For extra protection, stay out of the sun until after 4 p.m.
  • Depending on the type of sun rash, it may be beneficial to gradually expose yourself to more light in the spring. This might help reduce the likelihood of developing a rash. Work with your doctor to be on the safe side.

Sun rash often goes away on its own, but it can recur with exposure to sunlight.

Sun rash typically goes away within a few days, depending on the underlying cause. If your rash recurs despite taking precautions or doesn’t seem to be improving with treatment, call your doctor.