Does Oxsoralen (methoxsalen) cause side effects?

Oxsoralen (methoxsalen) is a naturally occurring photoactive chemical found in the seeds of the Ammi majus (Umbelliferae) plant and in the roots of Heraclem candicans. It belongs to a group of compounds known as psoralens, or furocoumarins. 

Oxsoralen lotion is used to treat vitiligo (leucoderma). It is used in conjunction with controlled doses of ultraviolet A light (UVA, 320-400 nm) or sunlight. 

The exact mechanism of action of Oxsoralen is not known. Oxsoralen has several biological actions that may be responsible for its medical effects. Oxsoralen is a photosensitizer that increases the reaction of skin cells to UVA. 

Some experts suggest that Oxsoralen improves vitiligo by stimulating melanocytes (melanin forming skin cells) to move up the hair follicle and to repopulate the epidermis. Oxsoralen also combines with DNA in skin cells, leading to inhibition of DNA synthesis, cell division, and reduced formation of new skin cells. 

Administration of Oxsoralen combined with UVA exposure causes cellular damage, leading to skin inflammation and redness. The damaged skin heals after several days to weeks.

Common side effects of Oxsoralen include

Serious side effects of Oxsoralen include

  • severe burns from over exposure to UVA or sunlight.

Drug interactions of Oxsoralen include drugs that cause sun sensitivity, such as coal tar or coal tar derivatives, doxycycline, tetracycline, demeclocycline, methylene blue, griseofulvin, thiazide diuretics, fluoroquinolone antibiotics, and several other drugs, because this will increase the risk of severe skin burns when using Oxsoralen. 

Oxsoralen lotion has not been studied in pregnant women and it is unknown if Oxsoralen can harm the fetus when used by a pregnant woman. It is unknown if Oxsoralen is absorbed into the bloodstream when it is applied to the skin. Oxsoralen lotion should be used in pregnant women only when clearly needed. 

It is unknown if Oxsoralen is excreted in breast milk after it is applied to the skin. Consult your doctor before breastfeeding.

What are the important side effects of Oxsoralen (methoxsalen)?

Common side effects include:

  • Severe burns from over exposure to UVA or sunlight
  • Blisters
  • Sun sensitivity (photosensitivity)

Oxsoralen (methoxsalen) side effects list for healthcare professionals

Systemic adverse reactions have not been reported. The most common adverse reaction is severe burns of the treated area from overexposure to UVA, including sunlight. TREATMENT MUST BE INDIVIDUALIZED.

Minor blistering of the skin is not a contraindication to further treatment and generally heals without incident. Treatment would be the standard for burn therapy.

Since 1953, many studies have demonstrated the safety and effectiveness of topical methoxsalen and UVA for the treatment of vitiligo when used as directed.

What drugs interact with Oxsoralen (methoxsalen)?

No information provided.

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Medically Reviewed on 9/25/2020
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.