Photodermatitis: Symptoms, Causes, Diagnosis and Treatment Plan

What is it? Also called poisoning by sunlight

Photodermatitis is a term that refers to different allergic reactions caused by sunlight. It can be acute (sudden) or chronic (ongoing). Another term used for the same condition includes polymorphism.

Depending on the amount of exposure to the sun, reactions may vary from person to person. They usually occur after an episode of intense sun exposure, usually in the spring or early summer.

Symptoms can range from mild, such as sunburn, including red, itchy, hot patches and scaly skin, to more severe forms such as fragile vesicles or blisters (fluid-filled, like bubbles under the skin) and dark, thick skin on the skin. chronic skin


People with photosensitivity can also be affected by indoor fluorescent lighting, commercial tanning lamps and tanning beds.


The exact number of patients is not known as many patients do not seek medical attention. What is known is that women are more prone to suffer from photosensitivity.

The condition can have a strong psychosocial impact on patients with women more likely than men to suffer from emotional distress.

Signs and symptoms

  • Redness, swelling and pain
  • Itching or blisters.
  • Eczema, injuries.
  • Dark patches on the skin.
  • Chills and headaches.
  • Fever, nausea, vomiting.
  • Fatigue and dizziness

Chronic sensitivity leads to thickening and scarring of the skin and increases the risk of skin cancer.


Phototoxic – direct effects of UV rays or the taking of chemical substances or substances that make the skin more sensitive to UV light.

Photoallergic – effects that occur when a person exposed to the sun is taking certain chemicals or drugs that make their skin allergic to sunlight.

Certain diseases, including lupus and eczema, make the skin sensitive to light, as well as diabetes mellitus and thyroid disease.

Genetic or metabolic factors (hereditary diseases or conditions such as pellagra, caused by lack of niacin, vitamin B-3).

Herbs such as St. John’s wort, angelica seed or root, arnica, celery stalks, grated oil and lime.

The direct toxic effects can be caused by:

  • Antibiotics, such as tetracycline and sulfonamides.
  • Antifungals, such as griseofulvin.
  • Derivatives of coal tar and psoralens, used topically for psoriasis.
  • Retinoids, such as tretinoin and drugs that contain retinoic acid, used for acne.
  • Non-steroidal anti-inflammatories (NSAIDs).
  • Chemotherapy agents.
  • Sulfonylureas, oral medications used for diabetes.
  • Antimalarial drugs, such as quinine and other medicines, used to treat malaria.
  • Diuretics
  • Antidepressants, such as tricyclics, used for depression.
  • Antipsychotics, such as phenothiazines.
  • Anti-anxiety medications, such as benzodiazepines.

Allergic reactions can be caused by:

  • Fragrances
  • Sunscreens with para-amino benzoic acid that absorbs ultraviolet light and acts as a sunscreen.
  • Industrial cleaners containing salicylanilide.
  • Risk factor’s.
  • Sunlight
  • Having clear skin to light, red or blond hair, green or blue eyes.
  • Suffering from conditions such as lupus, porphyria, or polymorphic light rashes, diabetes mellitus or thyroid disease.
  • Underlying infection
  • Previous episodes of sun poisoning.
  • The use of contraceptive pills, as well as drugs that can cause direct toxic effects mentioned above.
  • Use of plants or topical creams containing psoralens.
  • Use of coal tar lotions.
  • Perfumes with lemon oils and other products that possibly cause allergic reactions.
  • Exposure to UV rays for more than 30 minutes, as well as exposure between 11 and 2 in the morning when 50% of UV radiation is emitted.

How is the diagnosis made?

Your doctor will perform a physical exam to examine your skin and take a detailed history of


  1. Sun exposure.
  2. Family diseases.
  3. Medications used.
  4. Topical creams used.
  5. Job.
  6. Habits – gardening, etc.

And it will ask for the following tests:

  1. Photo-test exposing it to ultraviolet light.
  2. Photo-patch testing by applying suspect agents or chemicals to the patient’s back for 48 hours. The patch is removed and the skin reaction is followed for a week.
  3. Skin biopsy in which a piece of skin tissue is sent to a pathologist to identify the underlying problem (if diseases are suspected).

Your doctor can even see a dermatologist.


In order to avoid reactions to the sun, make sure that:

  1. Limit exposure of the skin to the sun, especially in the intense midday sun.
  2. Avoid topical medications or creams that cause problems.
  3. Use sunscreens that protect against UVA and have a sun protection factor (SPF) of 30 – 50.
  4. Cover with a long-sleeved shirt, long pants, and a wide-brimmed hat.
  5. Avoid the use of tanning devices.

Treatment plan

  • For sunburn.
  • Apply cold water or ice packs for sunburn, as well as blisters and rashes.
  • Drink plenty of fluids, water would be the best.
  • Apply aloe vera lotions that have soothing effects.
  • Use Tylenol or aspirin for pain or corticosteroid creams to relieve pain, redness and itching.
  • Prednisone pills can be prescribed for severe reactions.

Therapies of medicines

Drug treatments are usually not necessary because skin rash and other symptoms usually disappear on their own in seven to 10 days if preventive measures are applied.

However, if the steps of prevention are not effective, a doctor may decide to prescribe a medication, such as a corticosteroid cream, to reduce inflammation and to control rashes.

For patients extremely sensitive to the sun, doctors can even prescribe azathioprine to suppress the immune system. Those people who can not be treated with phototherapy can receive hydroxychloroquine, thalidomide, beta-carotene or nicotinamide.

Thalidomide should be used with care and avoided by pregnant women and those who try to conceive, since the medication has been found to cause serious birth defects.