This medication is used to treat cutaneous T-cell lymphoma (CTCL), a type of cancer that affects the skin and blood and sometimes the lymph nodes and other organs. CTCL is caused by the uncontrolled growth of abnormal white blood cells in the skin. This drug is used in a procedure called photopheresis. Some of your blood is removed from your body through a vein and goes into a special machine that separates the white blood cells. The machine adds methoxsalen to these white blood cells, then shines ultraviolet (UV) light on them. Then the machine returns the treated cells (and the rest of your blood) to your body through the same vein. Your immune system is thought to react to the treated cells and other similar untreated T-cells that are not working properly. This effect helps to restore your immune balance and lessens the skin problems (such as rash, plaques, tumors) of CTCL. Methoxsalen is known as a psoralen photosensitizer. It works by making the treated white blood cells more sensitive to UV light.

See Uses section.

This medication is injected into your collected white blood cells during photopheresis by a health care professional. This medication is used as directed by your doctor, usually once a day for 2 days in a row. Photopheresis is usually repeated every 4 weeks depending on your response to treatment.

The dosage is based on your medical condition, the amount of white blood cells collected, and response to treatment.

See also Precautions section.

Dizziness, headache, weakness, leg cramps, or bitter/sour taste in the mouth may occur. Skin freckling, dry skin, and skin aging may also occur. If these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• depression
• swollen ankles/feet
• new/unusual skin sores
• irregular heartbeat

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before using methoxsalen, tell your doctor or pharmacist if you are allergic to it; or to sunlight; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• unusual or bad reactions to other psoralen products
• conditions that make you sensitive to light (such as lupus, certain porphyrias, xeroderma pigmentosum, albinism)
• removal of natural lens in the eye
• coal tar/UVA treatment
• radiation treatment
• arsenic treatments
• other skin cancer (melanoma, basal cell or squamous cell carcinomas)
• cataracts
• liver problems
• kidney problems
• heart problems

For 24 hours after treatment with this medication, your eyes and skin will be more sensitive to the sun, including sunlight through a glass window. Limit your time in the sun. Avoid tanning booths and sunlamps. To protect your skin during this time, use sunscreen and wear protective clothing when outdoors. To protect your eyes, wear dark wrap-around UV-absorbing sunglasses. Tell your doctor right away if you have vision changes, skin blisters/redness/swelling/peeling, or if you get sunburned. Ask your doctor for details.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using methoxsalen. Methoxsalen may harm an unborn baby. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

A product that may interact with this drug is:

• fezolinetant

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: serious burning/blistering of skin.

Lab and/or medical tests (such as blood counts) should be done while you are using this medication. Keep all medical and lab appointments. Consult your doctor for more details.

It is important to get each scheduled treatment with this medication as directed. If you miss a treatment, ask your doctor for a new treatment schedule.

Not applicable. This medication is given in a hospital or clinic and will not be stored at home.