Photodermatitis is an abnormal skin response to ultraviolet (UV) rays, particularly sunlight. It can be acute or chronic. UV rays are classified by wavelength and the greater the wavelength, the greater the risk of developing photodermatitis. UVB rays range from 290 to 320 nm and may cause sunburn, tanning, aging, or cancer-causing changes to the skin. UVA rays range from 320 to 400 nm and may cause reactions to light even through window glass. Ninety percent of the UV radiation from sunlight comes from UVA rays, 10% from UVB. Photoreactions from UV rays depend upon the amount of light reaching the earth. This is influenced by the season or time of year, latitude, thickness of the ozone layer, and topography.

Signs and Symptoms

What Causes It?

Certain chemical agents and drugs may predispose an individual to sunburn, an eczema-like reaction, or hives in reaction to UV rays. In the United States alone, there are more than 115 chemical agents and drugs that are ingested or applied to the skin that may elicit photodermatitis. The reaction may be related to an allergy or it may be a direct toxic effect from the substance. Below are examples of agents or circumstances that may trigger one or the other type of reaction:

Direct toxic effect:

Allergic reactions:

Photodermatitis may also result from some immune-related disorders such as systemic lupus erythematosus (SLE) or certain states of nutrient deficiencies, including pellagra, which is caused by niacin (vitamin B3) deficiency.

Who's Most At Risk?

What to Expect at Your Provider's Office

A physical exam and a detailed history of exposure to sensitizers (see section entitled What Causes It?) and UV rays are important for diagnosis. A review of all body systems, including blood and urine tests, helps detect any related disease. Allergy tests may help identify substances that trigger or worsen the condition.

Treatment Options


These measures may help prevent photodermatitis:

Treatment Plan

For blisters or weepy eruptions, apply cool, wet dressings. With certain types of photodermatitis, doctors may actually use phototherapy (controlled exposure to light for treatment purposes) to desensitize the skin or to help control symptoms.

Drug Therapies

For extremely sensitive patients, doctors may prescribe azathioprine to suppress the immune system. Short-term use of glucocorticoids may help control eruptions. For those who cannot be treated with phototherapy, doctors may prescribe hydroxychloroquine, thalidomide, beta-carotene, or nicotinamide (see section entitled Nutrition for details regarding the latter two). Note: Thalidomide causes severe birth defects and therefore should never be used by women who either are or wish to become pregnant.

Complementary and Alternative Therapies


Particular nutritional deficiencies can contribute to photosensitivity. Pellagra, for example, is caused by a niacin deficiency. Recent research results suggest that antioxidant nutrients, including beta-carotene, may help lessen the severity of photodermatitis.


Similar to photosensitizing medications, certain herbs can trigger photodermatitis; such herbs include St. John's wort (Hypericum perforatum), angelica seed or root (Angelica archangelica), celery stems (Apium graveolens), rue (Rutae folium), and lime oil/peel ( Citrus aurantifolia).


While scientific studies of homeopathy specifically addressing photodermatitis have not been conducted to date, individual reports suggest that homeopathic remedies may be a useful adjunct for the prevention and treatment of photodermatitis. An experienced homeopath considers each individual case and may recommend treatments tailored to address both the underlying condition and any current symptoms.

Prognosis/Possible Complications

Most photosensitivity reactions go away on their own and cause no permanent harm. However, symptoms can be severe when associated with a systemic disorder or when the exposure has been severe. Some photosensitivity reactions can continue for years after exposure ends.

Complications may include:

Following Up

Patients who need steroids to treat photosensitivity reactions must be monitored closely. In addition, anyone with a history of photodermatitis or photoreactivity should keep track of the frequency and duration of symptoms. This information can help determine the cause and appropriate treatment.