This medication is a photosensitizer (psoralen derivative), used for vitiligo along with ultraviolet light. 

Contraindicated in patients with porphyria (reddish-purple color urine), acute autoimmune disease or white patches and in children less than 12 years.

PO- Adults and children 12 years of age and over— The recommended dose is 20 to 40 mg, two to four hours before ultraviolet light A (UVA) exposure.

It comes as a tablet to take by mouth, with food or milk.

• Caution should be exercised in patients with history of allergy to sunlight, auto immune disease, vision problems, heart, kidney or liver disease, infection, stomach problem, skin cancer, any allergy, elderly, during pregnancy and breastfeeding.

• Avoid exposure to sunlight.

• Take proper diet as directed by your physician; otherwise it may increase your skin sensitivity.

•  Most Common: Itching, irritation and nausea.
•  Skin: Blistering, redness, rash and swelling.
•  Central Nervous System: Dizziness, headache, depression, nervousness and trouble in speaking.

Proper dressing needed for the affected area before and after the treatment.

Store it at room temperature (150 to 300 C) away from heat and light.