What Is Polymorphic Light Eruption?

If you’ve ever experienced a bumpy, itchy rash on your arms on the first sunny day of the year, you may have been suffering from polymorphic light eruption (PMLE)! This slightly mysterious condition is a reaction to sunlight on the skin, but it can be confused with other rashes on sensitive skin. Let’s take a closer look at PMLE.

What does PMLE look like?

PMLE is the commonest photosensitive condition, and manifests in quite a variety of ways, hence its name ‘polymorphic’ (‘many shaped’). Skin can be affected in a number of ways:

  • red, flushed or differently coloured (depending on skin colour) patches on the skin
  • red, flushed or differently coloured (depending on skin colour) raised plaques on the skin
  • dry patches or plaques, resembling dermatitis
  • blisters
  • Small bumps (aka pinpoint papules), especially in skin of colour
  • Thickened or hard areas of skin 
  • Bull's-eye or target shaped patches
  • Areas of itchy spots on exposed skin
  • Itchiness but without rashes or spots

When does it happen?

PMLE is a consequence of skin being exposed to sunlight. It often happens quite suddenly after the skin has been exposed to sunlight, within 30 minutes or so. For those susceptible to PMLE, it can occur on the first day of spring or of a holiday, especially if the person affected lives in a region where the winters are relatively cold, compared to the summer. It can happen just once, as the temperature rises, or it can continue to affect people throughout the summer.

Who gets PMLE?

Although anyone of any sex or race can experience PMLE, it’s women over 30 with fair skin, who live in cooler, less sunny countries where there’s a definite shift of seasons, who are most likely to be affected.

However, it’s fairly common, with 1:10 people being affected to some extent or other.

Why does it happen?

PMLE is a hypersensitive reaction to UV light: compounds in the skin react disproportionately to ultraviolet radiation and trigger an inflammatory response. It’s not totally clear why PMLE happens to some people and not others, but the physiological reaction to UV light in sunshine includes long wave UVA that can come through glass, so it’s possible to be affected even if you’re inside, and even if you’re wearing light clothing. 

How can you tell it’s PMLE and not something else?

Despite its varied appearance, PMLE can be distinguished from various other rashes and inflammation of the skin in two basic ways:

  1. It occurs in response to a change in sunlight
  2. It occurs where sunlight hits the skin (though remember it can affect skin under light clothing too)

Other itchy rashes that PMLE could be mistaken for include:

Heat rash: is more widely spread across the body, including areas where sunlight hasn’t reached; it’s to do with the body overheating, rather than direct exposure to sunlight.

Lupus: a lupus malar rash is also photosensitive but it mostly occurs on the face in a characteristic ‘butterfly’ appearance, and is generally accompanied by other symptoms of unwellness.

Rosacea: occurs only on the face, not on arms or the exposed skin of the neck

Dermatitis: occurs in response to irritants and isn’t confined to one season

Chemical photosensitivity: certain substances (medications, plants, chemicals) can induce photosensitivity

Sun urticaria: an extreme allergic reaction to sunlight that manifests as hives, but sometimes also affects people with nausea, headaches and low blood pressure

PMLE is not contagious and is not related to skin cancer.

What can you do about it?

Although there’s no current way of ‘curing’ PMLE, there are a few options for managing it.

  • Avoid sun exposure, especially during a flare! Use high factor sunscreen, tightly woven clothes, or stay indoors during the hours of strong sunlight
  • Take antihistamines
  • Desensitise your skin with gradually increasing exposure at the beginning of summer
  • In severe cases, UV desensitisation therapy can be prescribed
  • Some doctors will prescribe hydrocortisone creams for use during a flare, but steroids should be used very sparingly and are not an appropriate treatment long term
  • Emollients can be used on thickened skin

You might find Balmonds emollients useful to help keep your itchy skin in good, healthy, resilient condition. Although creams and balms cannot ‘cure’ or treat the root cause of PMLE (or other chronic skin conditions), they are effective at providing hydration, locking in moisture, smoothing thickened areas, and keeping skin soft and supple.

Our products do not contain sunscreens! Do not apply oils or oil-based balms like Skin Salvation to exposed areas of skin in bright sunlight, as the oils can make the skin more likely to burn.

Recommended products:

Balmonds Skin Salvation
with hemp and beeswax

Balmonds Daily Moisturising Cream
with shea butter and calendula

Balmonds Cooling Cream
with shea, menthol, aloe vera & lavender

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