Methoxsalen (Oral)

Methoxsalen is a photoactive compound that occurs naturally in various plant species, which is available in prescription drug format to aid in the treatment of skin conditions such as vitiligo and psoriasis.


Methoxsalen is sold under the names 8-Mop and Oxsoralen-Ultra to patients who suffer from skin conditions including vitiligo, psoriasis, eczema and some lymphomas. This medication is photoactive, meaning it reacts to UVA light rays from lamps or sunlight. By modifying the way the cellular makeup of the skin reacts to these light rays, Methoxsalen is effective in clearing up these skin conditions.

Extracted from a plant known as Ammi Majus, Methoxsalen occurs naturally in other plants as well and is used in aromatherapy oils and some perfumes. This substance has been known to darken the skin when used and is typically removed from plant extracts before they are made into perfumes. It is effective, however, for treatment of certain skin diseases.

Patients are typically prescribed not only a dose of Methoxsalen but also treatment with ultraviolet A lamps. While these ultraviolet rays are beneficial in and of themselves in some skin conditions, by increasing the cellular response to these rays, Methoxsalen provides a more efficient treatment.

There are some medical experts who, through extensive study, have determined that Methoxsalen encourages melanin cells in the skin to repopulate in the epidermis, curing the condition of vitiligo. Another action attributed to Methoxsalen is the decrease in production of skin cells, which clears up psoriasis in most patients. Methoxsalen has been approved for use since 1954 and is available in a generic brand format.

Conditions Treated

Type Of Medicine

  • Furanocoumarin
  • Antipsoriatic
  • Photosensitizing agent
  • Psoralen

Side Effects

Occasionally, in affecting the way the skin cells of the body process light, Methoxsalen may also cause unwanted symptoms. Some of these symptoms can endanger your long-term health. Should you experience any of the symptoms listed below, report them to your doctor right away:

You will experience mild skin redness for one to two days after you take your first dose of Methoxsalen, which is normal and should not cause you concern. However, if the redness is accompanied by blisters or becomes painful, let your doctor know right away.

Methoxsalen treatment places you at a higher risk for developing certain skin cancers. Perform regular skin examinations on yourself and let your doctor know of any sores that aren't healing, new growths on the skin or changes to any existing growths in the way they feel or appear.

Your skin may become prematurely aged in appearance after your dose of Methoxsalen, similar to a person who tans excessively. This effect is permanent.


Take your prescribed dosage of Methoxsalen exactly as your doctor has written it for you. Do not deviate from the amount you are supposed to take or the frequency in which you are to take it and do not take it longer than you are prescribed.

Patients who are diagnosed with psoriasis and mycosis fungoides and prescribed the capsule form of Methoxsalen are typically directed to take 0.6 milligrams per kilogram of body weight if they are over 12 years of age. This dosage should be timed to be two hours before their UVA light treatment, which will occur two to three times per week in two-day increments.

Vitiligo patients over 12 years of age will be prescribed 20 milligrams of Methoxsalen per day to be taken two to four hours prior to their UVA light therapy treatment. This treatment will be administered two to three times per week in two-day increments.

Patients over 12 who are prescribed the soft gelatin capsule form of Methoxsalen for treatment of their psoriasis will typically be given a dose equal to 0.4 milligrams per kilogram of body weight to be taken 90 to 120 minutes prior to their UVA light therapy, which occurs two to three times per week in two-day increments.

If you miss a dose and it is too close to your UVA therapy treatment, you need to get in touch with your physician who will want to reschedule your light therapy. Check with your doctor if you miss a dose and do not double dose.

It will take up to eight weeks for you to experience an improvement in your condition. Continue to follow your doctor's prescribed amount of Methoxsalen carefully, with the correct amount taken as specified prior to your light therapy treatment.

Patients experiencing stomach upset when taking their Methoxsalen hard gelatin capsules may find that taking them with a meal or with milk may ease this symptom. Patients who take the soft gelatin capsules are able to take their dosage with low-fat foods or milk to avoid stomach upset.


Reactions to this medication or others that you have experienced in the past should be communicated to your physician prior to taking your first dose of Methoxsalen. Include any sensitivity you have experienced to dyes, perfumes, preservatives, foods or animals as well.

You will be provided with a printed patient information leaflet that you should read and comprehend prior to taking your first dose of Methoxsalen. Ask any questions necessary of your physician or pharmacist to be sure that you understand how this medication will work on your condition, what should be avoided during your treatment and any adverse health effects to be alert for.

Methoxsalen may interact poorly with certain foods, which should be avoided:

  • Lime
  • Parsley
  • Figs
  • Parsnips
  • Carrots
  • Mustard
  • Celery

Otherwise, it is up to you if you would like to take your dosage with milk or food to avoid any stomach upset from the medication. Patients who are taking the soft gelatin capsules should take them with low-fat milk or food only.

Pediatric patients who are younger than 12 have been proven to be more sensitive to the adverse health effects of this medication than adult patients and are therefore not candidates for treatment with Methoxsalen.

It is unknown if Methoxsalen works different for geriatric patients, as this age group has not been studied with regard to safety or effectiveness. Use in this age group should be done with caution.

No adequate data has been provided that proves Methoxsalen is safe or effective in pregnant women. Women should not take Methoxsalen treatment while they are pregnant and should avoid becoming pregnant while taking the medication. Discuss the possible risks to your unborn child with your doctor if you are pregnant and need treatment with this medication.

Studies have not been performed on nursing mothers to determine if Methoxsalen is passed to their infants via their breast milk. As this medication is not safe for young children, it is recommended that nursing mothers avoid Methoxsalen treatment until their children have been weaned.

Certain medications interact poorly with each other and that is the case with several medications and natural substances when combined with Methoxsalen. To avoid any risks to your health, it is best to avoid taking other medications during your treatment with this drug. At least let your physician know and seek approval to take the prescriptions you are currently on, any over-the-counter medications you take regularly and the vitamin or herbal supplements you are treated with.

The following medications should be avoided when taking Methoxsalen, but may be necessary for you. Alert your physician to the fact that you take these so that your dosage can be adjusted to protect your health:

  • Clozapine
  • Anagrelide
  • Tegafur
  • Pirfenidone

The risk for certain adverse health effects may be greater if you are taking the following medicines, which should be disclosed to your physician:

  • Phenytoin

  • Fosphenytoin

Discuss your consumption of alcoholic beverages and use of tobacco products, if applicable, with your physician in regard to their interactivity with Methoxsalen. Your physician may advise you to stop these activities while you are taking this medication.

Disclose your full medical history to your physician in case you suffer from any conditions that will be made worse by taking Methoxsalen. Make a special point to tell your doctor if you have:


There may be active ingredients in Methoxsalen capsules that your body interacts poorly with. Alert your physician if you have ever experienced allergy symptoms to this or other substances.

You will be required to visit your physician for regular check-ups to determine if Methoxsalen is effective on your condition. You will also be observed for any adverse effects on your health due to the drug and will most likely have your eyes tested for this purpose.

Your skin will be more sensitive to the sun during your treatment, with your lips being one of the most vulnerable areas. Minimize your sun exposure, even through windows indoors. If you must be outdoors, take the following precautions:

Before treatment:

  • Cover your skin with protective clothing like full-length slacks and sleeves, gloves and hats with brims for at least one day prior to taking your Methoxsalen.
  • Use a lip sunblock of at least SPF15.
  • Check with your physician prior to using any sun protection lotions or other treatments on your other skin, as these areas are being treated and should not have these types of products applied.

After treatment:

  • Keep skin covered as above for at least eight hours, protecting your lips with SPF15 sunblock treatment.
  • After treatment, your doctor may approve the use of sun protection lotions and other treatments on your skin. Check with your doctor to be sure.

Use extra caution for the next two days after each treatment if you have any outdoor time planned. Avoid sunbathing at any time during your treatment.

Protect your eyes after your dose of Methoxsalen, as they can also become more sensitive to the sun after you have taken this medication. Wear wrap-around sunglasses that are formulated to absorb or totally block UV light. A serious increase in your risk of developing cataracts will occur when you take this medication, so consult your doctor on the proper sunglasses to wear. You may even be affected by sunlight coming through windows when you are indoors, so be aware of this risk and take the appropriate steps to protect yourself.

You may experience dry, itchy skin as the result of your treatment with Methoxsalen. Before you use any product on your skin, make sure you get it approved for use by your physician.

If you are pregnant or miss a period when you are taking Methoxsalen, notify your doctor immediately, as this medication has been known to cause fetal harm. Use effective birth control methods while you are being treated with Methoxsalen. Women who are breastfeeding should also avoid being treated with Methoxsalen, as it is undetermined if there is a risk to the infant involved.

Perform regular self examinations for signs of skin cancer, which include new or changing skin growths such as moles, scaly or crusted growths that appear suddenly, freckles or brown spots that appear where they weren't before and any changes to existing growths or spots on your skin. Continue to perform regular skin checks throughout your life, reporting any unusual skin symptoms to your physician.

Avoid taking this medication if you already have a health condition that makes you more sensitive to light such as porphyria, lupus or albinism or if you have had skin cancer already. If you have had eye surgery or injury to the lenses in your eyes because of trauma or genetic conditions, avoid use of Methoxsalen.

If you accidentally overdose yourself on Methoxsalen, seek emergency medical help through your physician or local EMS service or the poison control hotline.

Hypersensitivity to Methoxsalen can manifest itself through symptoms such as difficulty breathing, hives, swollen throat, face, lips or tongue. Seek emergency medical assistance if you have any of these signs or symptoms.

Let other physicians who care for you know that you are taking Methoxsalen capsules and UVA light therapy treatments, as they may run tests on you that are affected by this medication. Include any dental professionals who treat you at this time as well.


Keep your Methoxsalen capsules in their original packaging, closed and at room temperature. Do not allow your medication to be exposed to excessive moisture, heat, cold or light. Do not allow Methoxsalen to freeze and discard it safely if it does. Keep this and other medications out of sight and reach of children and pets. Dispose of this medication safely, according to local guidelines that you can obtain from your physician or pharmacist.


Skin conditions such as vitiligo, psoriasis, eczema and cutaneous lymphomas of some types require treatment that exposes the patients to UVA light. This treatment can be made more efficient if Methoxsalen is used a few hours prior to the light therapy, as it makes skin more sensitive to light. Derived from naturally occurring plant enzymes, the extracted Methoxsalen is a photosensitizing substance and affects the skin, eyes, lips and other areas of the body.

In making the skin more sensitive to light, Methoxsalen may also cause adverse health effects. There is an increased risk of irreversible premature aging as well as some skin cancers and eye injuries. Patients should protect themselves from the sun even when indoors during their treatment, even if they have not taken their first dose of Methoxsalen. Patients should remember to protect their lips with SPF 15 sun block or higher, but should not use sun block on the rest of their bodies without checking with their doctor first. Patients should wear protective clothing, hats with brims and full coverage sunglasses that deflect UV rays during their treatment.

Some patients have reported itching skin, headaches, nausea, depression, difficulty sleeping and dizziness when they've taken their first dose of Methoxsalen. Report any health or mood changes to your physician if they occur when you start taking this medication. Read all patient information provided and avoid the list of foods and medications indicated for your safety and the effectiveness of your treatment. Discuss any questions you may have with your physician or pharmacist.

Be alert for any changes to your skin including new growths and pigments as well as changes to old growths and freckles. It is recommended that you regularly examine yourself for signs of skin cancer for the rest of your life, as your risk is heightened with this treatment.

Avoid taking any other medications during this time unless they are specifically approved by your physician. Supply your medical staff with a list of medications you take even if they are non-prescription as well as your full medical history. Include any conditions that mean you are already sensitive to light such as lupus, sun allergy, and porphyria or skin cancer.