Sun Allergy (Photosensitivity): Types, Symptoms, Causes, Diagnosis, Treatment and Prevention

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A illustration of sun allergy

1Overview

Who wouldn’t like to go on a vacation during the summer or even just a walk in the park when the sun shines bright? Most people enjoy going out during this time but for some individuals who are sensitive to the sun (photosensitive), it would become a burden and it’s uncomfortable for them.

This is because when their skin is exposed to the sun, they will be having a rash after several hours and will last for a couple of days. This limits their outdoor activities and could hinder them from enjoying a summer getaway.

A sun allergy is described as various conditions where the body’s immune system overreacts to sunlight exposure. As a result, the patients may have itchy red rashes when exposed to the sun. This rash is commonly seen at the back of the hands, the “V” of the neck, and the outside surface of the upper and lower extremities (arms and legs).

In some severe and rare cases, hives and small blisters can occur and spread to skin even in areas that are not exposed. This is different from sunburn.

It is still unclear why the body develops this sun allergy. However, just like the other types of allergies, the body’s immune system identifies some components of the sun-altered skin as harmful, so it starts fighting against it by releasing immune defenses that create an allergic reaction.

2Types

Polymorphous light eruption (PMLE)

The Polymorphous light eruption (PMLE) is one of the most sun-related skin problems where the exposed skin becomes itchy and rash starts to appear after minimal exposure to the sun.

PMLE is common during spring and summer and it affects primarily the women, ages 20 to 40 years old and rarely in men. After the person has been exposed to sunlight several times towards the end of summer, the rashes may disappear and become less severe.

A repeated sun exposure can develop hardening wherein the person then becomes less sensitive to sunlight.  Some individual develops hardening only after a few days of exposure, others may take several weeks. But take note, the allergy comes back with the same intensity during spring time again.

Actinic prurigo (hereditary PMLE)

The Actinic prurigo (hereditary PMLE) is an inherited form of PMLE which means that this is passed down from parents down to their children. This occurs in Native American clients (American Indian population of North, South, and Central America). The symptoms are more intense than those of PMLE and which often begins in childhood and early adolescence.

Photoallergic eruption

The Photoallergic eruption is another sun allergy where there is a skin reaction that is caused by the effect of sunlight on a substance or chemical that has been used on the skin like sunscreen, perfumes, makeup or cosmetics, and antibiotic ointments. It could also be an effect of a prescribed medicines like antibiotics (especially sulphonamides and tetracycline); diuretics; phenothiazine for psychiatric illness, and some oral contraceptives.

Solar urticaria

The solar urticaria is a form of sun allergy that develops hives (itchy red bumps or wheals of varying sizes) after sun exposure. This is a rare condition that most often affects young women.

3Symptoms

If the client is exposed to sunlight for a longer period, the allergic reaction develops fast. The symptoms depend on the type of sun allergy a person has.

Polymorphous Light Eruption

The symptoms appear after about two hours of exposure to the sun.

  • Itchy/burning rash appearing on the areas that have been exposed to the sun including the “v” portion of the neck; arms and lower leg; and upper chest. The rash typically disappears within two to three days if the client avoids further exposure to the sun.
  • Headache
  • Chills
  • Nausea
  • Body malaise and feeling of discomfort
  • Appearance of plaques and small blisters happens in rare cases

Actinic prurigo (hereditary PMLE)

The symptoms are similar to those of PMLE. Usually, rashes are concentrated on the face, especially around the lips. Those who are living in tropical climates, the symptoms may continue to be present all year round.

Photoallergic eruption

  • Itchy red rash or tiny blisters appear on the sun-exposed area; in some cases, it spreads to skin even to areas that are unexposed to the sun.
  • Since it is a delayed hypersensitivity reaction, the symptoms appear one to two days after sun exposure but the duration of the symptoms is unpredictable. Once you have identified the substance causing the symptoms and you no longer use, the symptoms disappear.

 Solar urticaria

  • The eruption of hives (raised itchy welts) that usually appear on the exposed skin and sometimes in the uncovered skin within minutes of sun exposure. The symptoms fade 30 minutes after sun exposure but come back when exposed again to the sun.

4Causes

It is not clear yet why some people have a sun allergy and others do not. The following are some risk factors for having the sun allergy.

  • It may be caused by some medications, chemicals and some medical conditions that make the skin extra sensitive to the sun like tetracycline antibiotics, pain relievers like ketoprofen, sulphonamides or sulfa-based drugs.
  • Certain sun allergies are most common in people of certain racial backgrounds like the Caucasians where PLME is most common and Native Americans for hereditary PLME.
  • Other sun allergic reactions occur when your skin is exposed to certain chemicals and to Chemicals used in sunscreen, fragrances, disinfectants can be responsible for sun allergy.
  • Skin conditions like having dermatitis increase your chance of having a sun allergy.
  • If you have relatives with a sun allergy, you’re more likely to have a sun allergy if you have a parent or siblings with a sun allergy.

5Diagnosis

Photopatch testing

This test shows whether the allergic reaction is caused by a chemical substance used to your skin before exposure to the sun. The Identical patches are applied directly to the back. After one day, a portion of the area receives a dose of UV rays from a sun lamp. If there’s a reaction on the exposed area with light, most likely, it is caused by the tested substance.

Blood tests and skin samples

May be ordered by the doctor if he doubts that your symptoms may be caused by other skin conditions like lupus and not sun allergy. A Blood sample is extracted or a skin sample is taken for laboratory examination.

Phototesting or Ultraviolet (UV) light testing

This test uses a special photo lamp and is done to see how your skin will respond to the wavelengths of UV light. The test can identify which type of UV light causes the allergic reaction.

6Treatment

It is best to start with the strategies in preventing sun allergy like avoiding sun exposure for the symptoms not to get worse. Management of these symptoms depends on the specific type of sun disorder/allergy.

Polymorphous light eruption

  • Apply cool compress, with a damp washcloth, on the areas with an itchy
  • Spray yourself with cool water to feel refreshed
  • Apply cream containing cortisone on the area affected to relieve itchiness
  • Take over-the-counter oral antihistamines, like diphenhydramine, to relieve itching and relieves swelling; but for severe cases, the doctor prescribes a stronger dose of antihistamine and corticosteroid cream
  • The doctor may order phototherapy if the remedies are not effective. This treatment gradually exposes your skin to increasing doses of ultraviolet light. This is done three (3) times a week in three (3) weeks. If the phototherapy fails, a combination of psoralen and ultraviolet light (PUVA – treatment for severe dermatitis) is used by your doctor.
  • Beta-carotene tablets are used as supplements to treat sun allergy. These also contain antioxidants properties

Actinic prurigo (hereditary PMLE)

Since the symptoms of this type of sun allergy are more severe, the doctor may give drugs like prescription-strength corticosteroids, PUVA, thalidomide, antimalarial drugs (hydroxychloroquine) and beta-carotene.

Photoallergic eruption

  • Do not use the skin product or the medicine that is causing the allergic reaction.
  • Corticosteroid cream can be used in affected area of the skin

Solar urticaria

  • Use non-prescription oral antihistamine or a skin cream for mild hives to relieve itching
  • For severe hives, a prescribed corticosteroid cream or antihistamine that are much stronger can be used.

7Prevention

The following are strategies to prevent symptoms of sun allergy:

  • Apply a sunscreen frequently that has sun protector factor (SPF) of at least 15 or above before going out and reapply it every two hours. Use also a sunblock on your lips with an SPF of 20 or more. If you are fond of swimming, apply a generous amount of sunscreen to protect your skin.
  • Avoid exposure to the sun especially between 10:00 a.m. and 3:00 p.m. where the sun is at its peak. Try to limit your time under the sun.
  • An ultraviolet light protection sunglasses should be worn whenever you go outdoors.
  • Long pants and shirt with long sleeves as well as a wide-brimmed hat should be worn to protect the skin from sun exposure. Do not wear thin or loose clothing since the UV rays can pass through them.
  • Do not use medicines or skincare products that may cause a photoallergic Ask your doctor about the contraindications of the prescribed medicine you are using like, for example, avoiding sun exposure.