Trioxsalen (Oral)

Trioxsalen is an oral medication that is used in conjunction with UVA light therapy to increase skin tolerance to sunlight, enhance pigmentation, darken the skin and thicken the skin layers for the treatment of skin conditions such as vitiligo, eczema, psoriasis and others.


What is Trioxsalen?

Trioxsalen is an oral medication known as a psoralen and is used in conjunction with ultraviolet light sources to treat skin pigmentation conditions such as vitiligo. Psoralens such as Trioxsalen temporarily increase the skin's sensitivity to ultraviolet light. Plant-based psoralens were first used by the ancient Egyptians to treat skin diseases thousands of years ago. Today, synthetically manufactured psoralens such as Trioxsalen are used to treat skin conditions in a precise, effective way.

How does it work?

Trioxsalen affects skin pigmentation through photosensitizing the skin. Trioxsalen has been proven to be effective in the treatment of many types of skin conditions such as eczema, psoriasis and other atopic dermatitis diseases. The source agent of Trioxsalen is plant based in theory and manufactured synthetically, to provide effectiveness in photosensitization of the skin.

Trioxsalen is used along with UVA therapy as a treatment for vitiligo, eczema, psoriasis, fungoides and other skin conditions. Trioxsalen is taken to sensitize the skin to light in order for the ultraviolet light treatment to be more effective.

Physicians prescribe a dose based on the patient's skin type, color and severity of the condition. The dose of Trioxsalen is taken 1 ½ to 2 hours before the UVA light exposure therapy, which is repeated two to three times per week. The light exposure will increase as the treatment regime continues until the skin begins to respond, but the dose of Trioxsalen remains constant throughout the treatment.

Treatment of skin conditions

Trioxsalen, along with UVA therapy, is primarily used to treat a condition called vitiligo. Vitiligo is a long-term disease caused by the lack of melanin in the skin. Melanin is what gives pigment to the skin and those suffering from Vitiligo often show pale white patches on the hands or face, which can spread throughout the body. Vitiligo affects approximately 1% of the world's population.

Trioxsalen, as part of UVA therapy, is also used to treat eczema and psoriasis. Eczema is a long-term condition that causes the skin to become red, dry, cracked and itchy. Eczema can disappear over time with age or treatment. While similar in appearance, psoriasis is a hereditary, chronic autoimmune condition that causes red, flaky patches of skin normally on the elbows, knees and scalp and is covered with scaly, dead skin. There is no cure for psoriasis but its appearance can be improved with therapies such as PUVA.

Psoriasis patients can experience clearer or much-improved skin after 12 to 24 PUVA treatments. Eczema patients will experience the same success but will require a longer course of treatment. Patients with vitiligo can experience some revitalized pigmentation in the white patches associated with this condition, which is most successfully seen on the face. Treatment for vitiligo patients is typically twice per week over a period of two years but typically has to be repeated.

Conditions Treated

  • Vitiligo
  • eczema
  • psoriasis
  • skin pigmentation loss

Type of Medicine

  • Antipsoriatic

Side Effects

The side effects of Trioxsalen can include nausea and upset stomach, so it is advised that the dose is taken with food or milk to prevent any stomach issues. Users of Trioxsalen may also experience headaches, tender skin, nervous disposition, swelling of the hands, swelling of the feet, cramps in the legs, rashes on the skin, burning or itching. Use of Trioxsalen has been associated with premature skin aging, skin cancer and eye damage.

Trioxsalen can cause or increase the severity of eye conditions such as cataracts. Regular eye exams during Trioxsalen treatment regimes and after are recommended to detect any issues caused by the drug so they can be treated immediately.

Common side effects of Trioxsalen are usually not severe and are not a cause for concern. The most common effects are:

  • Itchy skin
  • Nausea

Less common are the following side effects, which typically go away after a short period of time. If these conditions persist or become severe, your physician should be notified immediately:

  • Dizziness
  • Depression
  • Nervousness
  • Insomnia
  • Headaches

If any of the following severe side effects occur while taking Trioxsalen, your physician should be notified immediately:

  • Skin blistering or peeling
  • Sore, red skin
  • Swollen feet and/or hands

Trioxsalen can cause serious sunburn if not taken correctly, following all drug interaction warnings on the label and as advised by your physician. Improper use of Trioxsalen can cause the skin's sensitivity to sunlight to increase in such a way that it puts the user at greater risk for skin cancer, cataracts and other skin issues. Those with allergies to dyes, preservatives, certain foods or animals should notify their prescribing physician before taking Trioxsalen.

Pediatric Side Effects

The same side effects, warnings and cautions apply to pediatric patients that are prescribed Trioxsalen as outlined for adults. Trioxsalen and UVA therapy is typically not prescribed for children unless all other options of treatment have failed to control their condition.

Geriatric Side Effects

No specific information exists on the effectiveness or any unusual side effects with regard to the use of Trioxsalen in older generations.

Breast Feeding Side Effects

No studies in breastfeeding women taking Trioxsalen have been performed to determine any risk to the infant. Potential risks and benefits should be discussed with your doctor in detail before beginning this or any other drug while breastfeeding.


Different patients will require different doses of Trioxsalen, so it is imperative that patients follow doctor's orders and refer to the directions on the label for any questions on dosage or missed doses. Specific attention should be paid to the number of doses each day and the time allowed between the doses as this prevents overdose situations, which can lead to severe side effects.

Dosage for Vitiligo

Adults and children 12 and above are typically prescribed 20 to 40 milligrams of Trioxsalen that are directed to be taken two to four hours before exposure to sunlight or any ultraviolet light source. The Trioxsalen/UVA treatment regime is typically two to three times per week with the treatments at least 48 hours apart. Children under 12 will have a dosage set by their physician that will be less than described above but follow the same regime.

Dosage for Sunlight Tolerance or Skin Pigmentation Increase

Adults 12 years and over will most likely be prescribed a dose of Trioxsalen of 20 to 40 milligrams to be taken two hours before UVA treatment. The treatment regime is also two to three times per week spaced 48 hours apart. Children under 12 will have their own dose customized by their physician.


It is important to always notify your doctor of all medications before starting a new treatment with Trioxsalen or any other drug. Use of other medications or treatments including herbal remedies and holistic therapy should be disclosed to your physician to determine their interaction with Trioxsalen and UVA therapy.

Medications known to interact with Trioxsalen include:

  • Ameluz
  • Aminolevulinic Acid
  • Levulan Kerastick
  • Methyl Aminolevulinate
  • Metvixia

Medications that may interact or decrease the effectiveness with Trioxsalen include the following:

  • Antibiotics (sulfa or tetracycline)
  • Water pills
  • Griseofulvin
  • Phenothiazines
  • Coal tar shampoos and treatments

The most common interaction to Trioxsalen is sunlight. Before each treatment, the skin should be covered for at least 24 hours by protective clothing including long-sleeved shirts, full-length trousers, hats with brims and gloves. Protect lips with sunblock lip treatments with at least SPF 15, but check with your doctor before using sunblock on any other parts of the body, as these can inhibit treatment.

After treatment, the skin should be protected from the sun for at least eight hours by wearing protective clothing as described above. Use sun block with at least SPF 15 or higher on lips and those areas that cannot be covered as directed by a physician. Caution should be taken for at least 48 hours after treatment if you spend any time in the sun.

Without question, your eyes should be protected from the sun for 24 hours after each dose of Trioxsalen with special sunglasses that completely block out ultraviolet light. Regular eye exams by your physician during treatment are recommended. Consult your doctor on the type of sunglasses that should be used for your protection.

Food interaction

As Trioxsalen is plant-derived, its effectiveness is based on the photosynthesis process. Due to the close relationship with plants, there are a few foods that interact with Trioxsalen and increase sun sensitivity even more, which can lead to burns and skin damage. Avoid the following foods during treatment with Trioxsalen:

  • Celery
  • Carrots
  • Parsnips
  • Parsley
  • Mustard
  • Figs
  • Limes

Other interactions

As with any drug, alcohol and tobacco use can alter or decrease the effectiveness of the treatment or cause unwanted side effects. Consult your doctor about the use of Trioxsalen while smoking or using alcohol and read all label cautions and warnings.

Other medical problems may interfere with the use of Trioxsalen, so make sure your doctor knows if you have any of the following conditions:

  • Cataracts or eye lens issues
  • Heart disease or blood vessel disease
  • Stomach problems
  • Liver disease
  • Drug allergies
  • Infections
  • Sun allergy or family history of a sun allergy
  • Lupus, Porphyria or other light sensitive conditions
  • Melanoma or other skin cancers or family history of skin cancers
  • Recent x-ray or cancer radiation treatments or upcoming treatment plans


Use of Trioxsalen has been known to increase the risk of developing skin cancer. Regular checks for any sores that do not heal, new growths or pigments or changes in any that exist should be regularly performed. Patients should be under close supervision when on Trioxsalen to monitor effectiveness and side effects.

Trioxsalen has been known to prematurely age the skin with prolonged use, which is a permanent effect of the drug.

Increasing the dose or frequency of the regime prescribed by your physician can cause unwanted side effects and decrease the effectiveness of Trioxsalen.


Your local emergency room, poison control center or emergency services number should be contacted immediately if an overdose is suspected.

Missed Dose

Missing a dose is not typically cause for alarm, but your physician should be notified. When you realize you've missed a dose, if it's near the time for the next dose, skip the missed dose and keep to the schedule. Do not double up or try to catch up. Do not stop any medications or treatments without doctor or pharmacist approval.


Trioxsalen should be stored at room temperature (between 59 and 86 degrees F, 15 to 30 degrees C) away from any sources of heat or sunlight. Trioxsalen should not be stored in a warm, steam-filled bathroom environment.


Trioxsalen is an effective treatment for vitiligo, psoriasis and other skin conditions. An oral medication, it is prescribed by a doctor in 20 to 40-milligram doses in conjunction with ultraviolet light therapy. Trioxsalen is plant derived and works by photosynthesizing the skin, darkening and thickening the dermis and making it more tolerant to sunlight and changing the pigmentation.

Trioxsalen should be taken only as prescribed by your physician in the dosage level and frequency of the regime designed for your condition by your healthcare professional. Use of Trioxsalen increases the risk of developing skin cancer. Trioxsalen has also been known to increase the premature aging of the skin, which is non-reversible. Side effects during treatment can include nausea and headaches as mild annoyances but also depression and eye damage on the severe side. Close monitoring by your physician during your treatment regime is recommended, including regular skin and eye exams.

This medication can react with other drugs and certain foods, so review all label cautions and warnings and discuss any existing treatments or conditions with your doctor before going on a course of treatment that includes Trioxsalen. Avoid Trioxsalen if you have skin cancer or a family history of skin cancer, liver or eye disease or heart, blood vessel or stomach conditions.

UV light exposure or overexposure can cause severe burns while on Trioxsalen therapy. Follow all instructions outlined by your doctor and on the medication label to avoid damaging your skin or eyes during treatment. Take precautions before and after dosage of Trioxsalen to cover exposed skin including lips, hands and feet when outdoors. Special sunglasses should be used during Trioxsalen treatment to avoid any damage to eyes.

Last Reviewed:
December 23, 2017
Last Updated:
April 23, 2018
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