Ive used it and it stimulates melanin production in the skin, the melanocytes producing a tan, its the steroid of tanning.
Its a drug thats prescribed to black people who lose their pigmentation like in blotches sometimes, I call em albino spots, called vitiligo but whitefolk can take and get tan with it, say they want to go for a hiking trip near the equator, good if youre whitie to get a tan first before you go so that have a tan to protect you from the sun. So they prescribe trisoralen. Taken about a half hour before you use the tanning bed. Itll make you a brotha.