Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. 8-Mop
  2. Oxsoralen-Ultra

Descriptions


Methoxsalen belongs to the group of medicines called psoralens. It is used along with ultraviolet light (found in sunlight and some special lamps) in a treatment called PUVA to treat vitiligo, a disease in which skin color is lost, and psoriasis, a skin condition associated with red and scaly patches.

Methoxsalen is also used with ultraviolet light in the treatment of white blood cells. This treatment is called photopheresis and is used to treat the skin problems associated with mycosis fungoides, which is a type of lymphoma.

Methoxsalen may also be used for other conditions as determined by your doctor.

This medicine is available only with your doctor's prescription.

This product is available in the following dosage forms:

  • Capsule, Liquid Filled

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Methoxsalen is a very strong medicine that increases the skin's sensitivity to sunlight. In addition to causing serious sunburns if not properly used, it has been reported to increase the chance of skin cancer and cataracts. Also, like too much sunlight, PUVA can cause premature aging of the skin. Therefore, methoxsalen should be used only as directed and it should not be used simply for suntanning. Before using this medicine, be sure that you have discussed its use with your doctor.

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Some of the side effects are more likely to occur in children up to 12 years of age, since these children may be more sensitive to the effects of methoxsalen.

Geriatric

Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of methoxsalen in the elderly with use in other age groups.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Anagrelide
  • Tegafur

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Fosphenytoin
  • Phenytoin

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Allergy to sunlight (or family history of) or
  • Infection or
  • Lupus erythematosus or
  • Porphyria or
  • Skin cancer (history of) or
  • Skin conditions (other) or
  • Stomach problems—Use of PUVA may make the condition worse
  • Eye problems, such as cataracts or loss of the lens of the eye—The light treatment may make the condition worse or may cause damage to the eye
  • Heart or blood vessel disease (severe)—The heat or prolonged standing associated with each light treatment may make the condition worse
  • Liver disease—Condition may cause increased blood levels of the medicine and cause an increase in side effects

Proper Use

Eating certain foods while you are taking methoxsalen may increase your skin's sensitivity to sunlight. To help prevent this, avoid eating limes, figs, parsley, parsnips, mustard, carrots, and celery while you are being treated with this medicine.

Methoxsalen usually comes with patient directions. Read them carefully before using this medicine.

This medicine may take 6 to 8 weeks to really help your condition. Do not increase the amount of methoxsalen you are taking or spend extra time in the sunlight or under an ultraviolet lamp. This will not make the medicine act any more quickly and may result in a serious burn.

If this medicine upsets your stomach:

  • Patients taking the hard gelatin capsules may take them with food or milk.
  • Patients taking the soft gelatin capsules may take them with low-fat food or low-fat milk.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (hard gelatin capsule):
    • For treating mycosis fungoides and psoriasis:
      • Adults and children 12 years of age and over—Dose is based on body weight and must be determined by your doctor. However, the usual dose is 0.6 mg per kilogram (kg) (0.27 mg per pound) of body weight taken two hours before UVA exposure. This treatment (methoxsalen and UVA) is given two or three times a week with the treatment spaced at least forty-eight hours apart.
      • Children up to 12 years of age—Dose must be determined by your doctor.
    • For vitiligo:
      • Adults and children 12 years of age and over—20 milligrams (mg) per day taken two to four hours before ultraviolet light A (UVA) exposure. This treatment (methoxsalen and UVA) is given two or three times a week with the treatment spaced at least forty-eight hours apart.
      • Children up to 12 years of age—Dose must be determined by your doctor.
  • For oral dosage form (soft gelatin capsule):
    • For psoriasis:
      • Adults and children 12 years of age and over—Dose is based on body weight and must be determined by your doctor. The usual dose is 0.4 mg per kg (0.18 mg per pound) of body weight taken one and one-half to two hours before UVA exposure. This treatment (methoxsalen and UVA) is given two or three times a week, with the treatment spaced at least forty-eight hours apart.
      • Children up to 12 years of age—Dose must be determined by your doctor.

Missed Dose

Call your doctor or pharmacist for instructions.

If you are late in taking, or miss taking, a dose of this medicine, notify your doctor so your light treatment can be rescheduled. Remember that exposure to sunlight or ultraviolet light must take place a certain number of hours after you take the medicine or it will not work. For patients taking the hard gelatin capsules, this is 2 to 4 hours. For patients taking the soft gelatin capsules, this is 1½ to 2 hours. If you have any questions about this, check with your doctor.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Precautions

Your doctor should check your progress at regular visits to make sure this medicine is working and that it does not cause unwanted effects. Eye examinations should be included.

This medicine increases the sensitivity of your skin and lips to sunlight. Therefore, exposure to the sun, even through window glass or on a cloudy day, could cause a serious burn. If you must go out during the daylight hours:

  • Before each treatment, cover your skin for at least 24 hours by wearing protective clothing, such as long-sleeved shirts, full-length slacks, wide-brimmed hat, and gloves. In addition, protect your lips with a special sun block lipstick that has a skin protection factor (SPF) of at least 15. Check with your doctor before using sun block products on other parts of your body before a treatment, since sun block products should not be used on the areas of your skin that are to be treated.
  • After each treatment, cover your skin for at least 8 hours by wearing protective clothing. In addition, use a sun block product that has a skin protection factor (SPF) of at least 15 on your lips and on those areas of your body that cannot be covered.

If you have any questions about this, check with your health care professional.

Your skin may continue to be sensitive to sunlight for some time after treatment with this medicine. Use extra caution for at least 48 hours following each treatment if you plan to spend any time in the sun. In addition, do not sunbathe anytime during your course of treatment with methoxsalen.

For 24 hours after you take each dose of methoxsalen, your eyes should be protected during daylight hours with special wraparound sunglasses that totally block or absorb ultraviolet light (ordinary sunglasses are not adequate). This is to prevent cataracts. Your doctor will tell you what kind of sunglasses to use. These glasses should be worn even in indirect light, such as light coming through window glass or on a cloudy day.

This medicine may cause your skin to become dry or itchy. However, check with your doctor before applying anything to your skin to treat this problem.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Itching of skin
  2. nausea

Less common

  1. Dizziness
  2. headache
  3. mental depression
  4. nervousness
  5. trouble in sleeping

Treatment with this medicine usually causes a slight reddening of your skin 24 to 48 hours after the treatment. This is an expected effect and is no cause for concern. However, check with your doctor right away if your skin becomes sore and red or blistered.

There is an increased risk of developing skin cancer after use of methoxsalen. You should check your body regularly and show your doctor any skin sores that do not heal, new skin growths, and skin growths that have changed in the way they look or feel.

Premature aging of the skin may occur as a result of prolonged methoxsalen therapy. This effect is permanent and is similar to what happens when a person sunbathes for long periods of time.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Portions of this document last updated: Feb. 01, 2024

Original article: https://www.mayoclinic.org/drugs-supplements/methoxsalen-oral-route/side-effects/drg-20064761