Solar Urticaria vs PMLE: Know the Differences

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Difference between Solar Urticaria vs PMLE: Solar Urticaria and Polymorphous Light Eruption (PMLE) are two different conditions which are associated with sun exposure. Solar Urticaria is a rare form of physical urticaria caused by sunlight or artificial UV radiation, which leads to hives or welts on the skin that are itchy and red, appearing shortly after exposure and typically subsiding within an hour. On the other hand, PMLE is a common photosensitivity disorder characterized by a rash of red, itchy bumps or patches on sun-exposed skin, which develops hours to days after exposure and can persist for days.

Difference between Solar Urticaria and PMLE

Solar Urticaria shows up as hives shortly after sunlight exposure, while PMLE causes a delayed rash on sun-exposed skin, therefore they differ in timing and presentation. The table below provides the differences between Solar Urticaria and PMLE.


Solar Urticaria

Polymorphous Light Eruption (PMLE)


Hypersensitivity to sunlight or artificial UV radiation

Not fully understood; immune system reaction to sunlight


Immediate onset of hives, itching, redness, and swelling upon sun exposure

Delayed onset of rash (hours to days after sun exposure), itching, redness, papules, or plaques


Symptoms typically resolve within hours after sun exposure ceases

Symptoms may persist for days or even weeks

Affected Areas

Exposed skin areas

Exposed skin areas, typically upper chest, arms, and legs


Rapid onset upon sun exposure

Delayed onset after sun exposure

Frequency of Occurrence

This can occur with minimal sun exposure

Usually occurs after prolonged or intense sun exposure


Antihistamines, sunscreens, phototherapy

Corticosteroid creams, antihistamines, phototherapy, avoidance of sun exposure


Sun avoidance, protective clothing, sunscreens

Sun avoidance during peak sunlight hours, use of broad-spectrum sunscreens, protective clothing

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What is Solar Urticaria?

Solar Urticaria is an extraordinary form of physical urticaria, which is characterized by the aid of hives, additionally called welts or wheals, that develop in response to certain physical stimuli. In the case of Solar Urticaria, publicity to sunlight or artificial ultraviolet (UV) radiation triggers the development of hives on the pores and skin.

Causes of Solar Urticaria

  • Ultraviolet (UV) Radiation: UV radiation from sunlight is assumed to cause a hypersensitive reaction in individuals with Solar Urticaria. It's thought that particular wavelengths of UV mild stimulate the release of histamine and other inflammatory materials in the skin, leading to function hives.
  • Immune System Dysfunction: Solar Urticaria may additionally result from an ordinary immune gadget response to UV radiation. In a few people, exposure to daylight might also trigger an immune response, inflicting the release of histamine and different chemical substances that lead to the development of hives.
  • Genetic Factors: There may be a genetic predisposition to Solar Urticaria, as it may from time to time run in families. Certain genetic factors might also make a few individuals more liable to grow an allergy to sunlight.
  • Photosensitizing Agents: Some medicines, chemical substances, or substances carried out to the skin can make it more sensitive to daylight, leading to a higher chance of developing Solar Urticaria. These substances are called photosensitizers and can include medicines, fragrances, cosmetics, and chemical substances used in sunscreen.

Symptoms of Solar Urticaria 

  • Development of Hives (Urticaria): The hallmark symptom of Solar Urticaria is the sudden look of red, raised, itchy welts or hives on the skin. These hives may also vary in length and shape and can appear on any part of the body exposed to sunlight.
  • Itching or Pruritus: The affected skin may experience intensely itchy or indignant, prompting individuals to scratch the area. Scratching can exacerbate the hives and can result in further discomfort.
  • Burning or Stinging Sensation: Some individuals with Solar Urticaria might also experience a burning or stinging sensation further to itching on the website online of the hives.
  • Swelling (Angioedema): In some instances, Solar Urticaria may be followed by way of swelling of the deeper layers of the skin, a circumstance referred to as angioedema. Angioedema normally affects the face, lips, eyelids, fingers, feet, or genitals and may cause a sensation of tightness or discomfort.

What is PMLE?

PMLE stands for Polymorphous Light Eruption, which is a common pores and skin circumstance characterized by a rash that happens after exposure to daylight or synthetic ultraviolet (UV). It typically manifests as itchy or burning purple bumps or patches on the skin, frequently performing within hours or days of sun exposure. PMLE tends to affect areas of the pores and skin that aren't typically exposed to daylight, including the chest, lower back, or legs. While the exact reason for PMLE isn't always fully understood, it is believed to involve an atypical immune response to daylight. 

Causes of PMLE

  • Genetic Factors: There seems to be a genetic predisposition to PMLE, as it regularly runs in households. Certain genetic versions may make individuals extra liable to growing an allergy reaction to sunlight.
  • Ultraviolet (UV) Radiation: Exposure to daylight or artificial UV mild is the number one cause of PMLE. The unique wavelengths of UV radiation, especially UVA and from time to time UVB, are believed to induce an odd immune response in individuals with PMLE.
  • Immune System Dysfunction: PMLE is an idea to involves an atypical immune response to UV radiation. In individuals with PMLE, publicity to sunlight triggers the discharge of inflammatory chemical substances in the pores and skin, leading to the function rash and signs.
  • Hormonal Factors: Hormonal adjustments, such as the ones happening all through puberty, pregnancy, or menstrual cycles, may exacerbate PMLE signs in a few individuals. Fluctuations in hormone stages can affect the skin's sensitivity to daylight.

Symptoms of PMLE

  • Rash: The hallmark symptom of PMLE is the improvement of a rash on sun-uncovered skin. The rash may additionally seem like red or crimson patches, bumps, or blisters. The affected regions can also experience gentle, itchy, or burning.
  • Itching or Burning Sensation: Many people with PMLE enjoy itching or a burning sensation in the affected regions of the skin. This discomfort can vary from moderate to extreme.
  • The appearance of Lesions: The rash may tackle various paperwork, which includes raised bumps, patches of redness, or small blisters. The lesions can be scattered or clustered collectively at the pores and skin.
  • Distribution of Rash: PMLE tends to affect areas of the skin that are usually now not exposed to sunlight all through the winter months, such as the chest, again, arms, and legs. The face and palms may also be affected in some cases.

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Similarities between Solar Urticaria and PMLE

  • Sunlight Trigger: Both Solar Urticaria and PMLE are brought about by using publicity to sunlight or artificial UV light. In both situations, signs commonly develop within minutes to hours of sun exposure.
  • Skin Reaction: Both conditions result in pores and skin reactions upon publicity to sunlight. In Solar Urticaria, the reaction regularly manifests as hives (wheals) or welts, which are raised, crimson, itchy patches on the pores and skin. In PMLE, the reaction commonly appears as a rash characterized by way of redness, bumps, or blisters on the skin.
  • Itching or Burning Sensation: Individuals with each Solar Urticaria and PMLE can also experience itching or a burning sensation within the affected areas of the pores and skin.

In summary, even though each Solar Urticaria and PMLE contain skin reactions to sunlight, Solar Urticaria especially results in hives rapidly after publicity, while PMLE offers a rash that develops hours to days after solar publicity and lasts longer. The remedy approaches for each circumstance may additionally vary, however, they regularly contain symptom control and photoprotection.

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What is Solar Urticaria?

Solar Urticaria is an extraordinary situation wherein hives or welts expand at the pores and skin rapidly after publicity to daylight.

What are the signs and symptoms of Solar Urticaria?

Symptoms generally encompass purple, itchy hives or welts at the pores and skin, that can vary in length and might seem within minutes of solar publicity.

What causes Solar Urticaria?

Solar Urticaria is thought to be due to an unusual immune gadget reaction to sunlight, especially to certain wavelengths of UV radiation.

What is PMLE?

PMLE is not an unusual pore and skin condition characterised by way of a rash that develops after sun publicity, especially in spring or early summer.

What are the symptoms of PMLE?

Symptoms usually encompass red, itchy bumps or patches on the skin, which might also appear step by step after solar publicity and persist for several days.

What causes PMLE?

PMLE is a condition to contains a strange immune response to sunlight, particularly to UV radiation.