Help! Am I Allergic to the Sun?

Polymorphous light eruption (also called polymorphic light eruption or PMLE) is a skin reaction that some people experience after sun exposure. It's often nicknamed a "sun allergy" or "sun poisoning," though it's not a true allergy. Here in Nashville, Tennessee we have wonderful sunny weather, so Dr. Jeffrey Berti and Dr. Toula Berti do diagnose and treat PMLE at their office, Nashville Dermatology Physicians, located in Brentwood. 

Polymorphous light eruption is known for an itchy or uncomfortable rash on sun-exposed skin, typically appearing in spring or early summer when your skin isn't used to stronger sunlight. It affects up to 10-20% of people in Western countries and is more common in women, younger adults (often under 40), and those with fairer skin.The good news is that PMLE is benign—it doesn't cause long-term damage or scarring, and episodes usually clear up on their own. With proper sun protection and management, many people can enjoy outdoor activities with fewer or no issues.

What Causes Polymorphous Light Eruption?

The exact cause isn't fully understood, but PMLE is thought to be an abnormal immune system response to ultraviolet (UV) light from the sun (or sometimes artificial sources like tanning beds).UV rays (especially UVA and UVB) interact with substances naturally present in your skin, creating changes that your immune system mistakes for something foreign. This triggers a delayed hypersensitivity reaction—similar to a type of allergic response—leading to inflammation. Immune cells (like T lymphocytes) rush to the skin, releasing chemicals that cause the rash.Some people have a genetic tendency to develop PMLE, as it runs in families in 15-46% of cases. It's more common in temperate climates and at higher altitudes where UV exposure can be intense. The reaction often happens on skin that's newly exposed after winter (like arms, chest, or legs) because those areas haven't "hardened" to sun yet. 

Symptoms of Polymorphous Light EruptionSymptoms usually start within a few hours to 2-3 days after sun exposure and can last 7-10 days (sometimes up to 2 weeks). The rash is "polymorphous," meaning it can look different from person to person—or even vary slightly in one person—but in any individual, it tends to follow a consistent pattern.Common features include:

• Itching or burning sensation (often the first sign).
• Red or pink inflamed skin (may be harder to see on darker skin tones).
• Dense clusters of small bumps (papules) or blisters.
• Raised, rough patches or larger blotchy areas.
• Occasionally, swelling or mild flu-like feelings (like chills or fatigue) in severe cases.

The rash typically appears on sun-exposed areas such as:

• Arms and hands.
• Neck
• Chest and upper back (like a "V" at the neckline).
• Legs.
• Shoulders.
• Less commonly on the face (the face often seems more tolerant).

It rarely affects areas usually covered by clothing.

Common Treatments and Management

Most cases of PMLE resolve on their own within 10 days without treatment or scarring. The focus is on relieving discomfort and preventing future episodes.For an Active Rash (Symptom Relief):

• Avoid further sun exposure to prevent worsening.
• Apply cool compresses or take cool baths to soothe itching.
• Use over-the-counter anti-itch creams like hydrocortisone or prescription mildd anti inflammatory cream
• Oral antihistamines (e.g., cetirizine or loratadine) can help with itching.
• For more severe or widespread rashes, a doctor may prescribe stronger topical corticosteroid creams or short courses of oral steroids (like prednisone) to reduce inflammation quickly or a non steroidal anti-inflammatory cream, like elidel.

Prevention and Long-Term Management:

• Strict sun protection is the cornerstone:
  • Seek shade, especially between 10 a.m. and 4 p.m.
  • Wear protective clothing (long sleeves, wide-brimmed hats, UPF-rated fabrics around neck).
  • Apply broad-spectrum sunscreen (SPF 30-50+ with high UVA protection) generously and reapply every 2 hours (or after swimming/sweating). Mineral sunscreens are good, especially La Roche Posay Anthelios Mineral sunscreen.
• Skin "hardening" (a natural or induced tolerance): Gradual, controlled sun exposure in early spring can help some people build resistance. For moderate-to-severe cases, doctors often recommend prophylactic phototherapy (e.g., narrowband UVB treatments 2-3 times weekly for 4-8 weeks before sunny season). This desensitizes the skin and prevents outbreaks in many patients (often 80%+ success rate), if it can be tolerated.  Some individuals cannot tolerate the sensation or do not want to have the inflammation. 
• In some cases, medications like hydroxychloroquine (an antimalarial drug) are used preventively for frequent or disabling episodes.

See a dermatologist if you have a rash that sounds like PMLE and we can confirm the diagnosis and rule out similar conditions. Many who live  with PMLE do find that symptoms improve over time or with consistent protection. Start your prevention routine early in the season, and don't hesitate to consult Dr. Berti for personalized advice—especially if planning a sunny vacation. With the right strategies, PMLE doesn't have to limit your enjoyment of the outdoors!  

As a Nashville-based dermatology practice, Dr. Toula Berti and Dr. Jeffrey Berti are here to help if you'd like to discuss your specific symptoms or treatment options. Stay tuned for our next article about UVA and UVB, and what is the difference.

1001 Health Park Dr.

Suite 470

Brentwood, TN 37027

615.212.2517