Photodermatitis
Encyclopedia
Photodermatitis, sometimes referred to as "sun poisoning" or photoallergy is a form of allergic contact dermatitis
Allergic contact dermatitis
Allergic contact dermatitis is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance....

 in which the allergen
Allergen
An allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....

 must be activated by light to sensitize the allergic response, and to cause a rash or other systemic effects on subsequent exposure. The second and subsequent exposures produce photoallergic skin conditions which are often eczema
Eczema
Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...

tous.

Causes

Many medications and conditions can cause sun sensitivity, including:
  • Psoralen
    Psoralen
    Psoralen is the parent compound in a family of natural products known as furocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered as a derivative of umbelliferone...

    s, coal tar
    Coal tar
    Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

    s, photo-active dyes (eosin
    Eosin
    Eosin is a fluorescent red dye resulting from the action of bromine on fluorescein. It can be used to stain cytoplasm, collagen and muscle fibers for examination under the microscope. Structures that stain readily with eosin are termed eosinophilic....

    , acridine orange
    Acridine orange
    Acridine orange is a nucleic acid selective fluorescent cationic dye useful for cell cycle determination. It is cell-permeable, and interacts with DNA and RNA by intercalation or electrostatic attractions respectively. When bound to DNA, it is very similar spectrally to fluorescein, with an...

    )
  • Musk ambrette, methylcoumarin, lemon oil (may be present in fragrances)
  • PABA (found in sunscreens)
  • Salicylanilide
    Salicylanilide
    Salicylanilide is a chemical compound which is the amide of salicylic acid and aniline. It is classified as both a salicylamide and an anilide....

     (found in industrial cleaners)
  • St John's Wort
    St John's wort
    St John's wort is the plant species Hypericum perforatum, and is also known as Tipton's Weed, Chase-devil, or Klamath weed....

    , used to treat clinical depression
    Clinical depression
    Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities...

  • Hexachlorophene
    Hexachlorophene
    Hexachlorophene, also known as Nabac, is a disinfectant. The compound occurs as a white to light-tan crystalline powder, which either is odorless or produces a slightly phenolic odor. In medicine, hexachlorophene is very useful as a topical anti-infective, anti-bacterial agent, often used in soaps...

     (found in some ℞ antibacterial soaps)
  • Contact with sap from Giant Hogweed
    Giant Hogweed
    Heracleum mantegazzianum, commonly known as giant hogweed, cartwheel-flower, wild parsnip, wild rhubarb, giant cow parsnip, or giant cow parsley, is a plant in the family Apiaceae. It typically grows to heights of , sometimes reaching...

    . Common Rue
    Common Rue
    The Common Rue , also known as Herb-of-Grace, is a species of rue grown as a herb. It is native to the Balkan Peninsula, southeastern Europe. It is sometimes grown as an ornamental plant in gardens, especially because of its bluish leaves, and also sometimes for its tolerance of hot and dry soil...

     (Ruta graveolins) is another phototoxic plant commonly found in gardens.
  • Tetracycline antibiotics
    Tetracycline antibiotics
    Tetracyclines are a group of broad-spectrum antibiotics whose general usefulness has been reduced with the onset of bacterial resistance. Despite this, they remain the treatment of choice for some specific indications....

  • NSAIDs.
  • Fluoroquinolone antibiotic: Sparfloxacin
    Sparfloxacin
    Sparfloxacin , trade names Zagam and Zagam Respipac, is a fluoroquinolone antibiotic used in the treatment of bacterial infections. It has a controversial safety profile...

     in 2% of cases.
  • Amiodarone
    Amiodarone
    Amiodarone is an antiarrhythmic agent used for various types of tachyarrhythmias , both ventricular and supraventricular arrhythmias. Discovered in 1961, it was not approved for use in the United States until 1985...

    , used to treat atrial fibrillation
    Atrial fibrillation
    Atrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...

  • Pellagra
    Pellagra
    Pellagra is a vitamin deficiency disease most commonly caused by a chronic lack of niacin in the diet. It can be caused by decreased intake of niacin or tryptophan, and possibly by excessive intake of leucine. It may also result from alterations in protein metabolism in disorders such as carcinoid...


Photodermatitis can also be caused by plants. This is called phytophotodermatitis
Phytophotodermatitis
Phytophotodermatitis is a chemical reaction which makes skin hypersensitive to ultraviolet light. It is frequently mistaken for hereditary conditions such as atopic dermatitis or chemical burns, but it is caused by contact with the photosensitizing compounds found naturally in some plants and...

.

Symptoms

May result in swelling, a burning sensation, a red itchy rash
Rash
A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell and may be painful. The causes, and...

 sometimes resembling small blisters, and peeling of the skin. Nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

 may also occur.
There may also be blotches of large to small areas where the itching may persist for long periods of time. In these areas an unsightly orange to brown tint may form, usually near or on the face.

Prevention

Prevention includes avoiding exposure to the sun and wearing sun block on the affected area.
  • Cover up: wear long sleeves, slacks
    Slacks
    Slacks is a colloquial term referring to trousers. However, it could also refer to:*Donovan Slacks, leader of a militant fishermen's uprising in 1920s Britain*Slacks Creek, Queensland, a suburb of Logan City , Queensland , Australia ....

    , and a wide-brimmed hat whenever harsh exposure is probable
  • Avoid chemicals that may trigger a reaction
  • Wear sunscreen
    Sunscreen
    Sunblock is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet radiation on the skin exposed to sunlight and thus helps protect against sunburn...

     at least factor 30 with a high UVA protection level
  • Wear gloves and/or remain indoors after handling fruits or plants which increase sensitivity to light
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