Hi. Thanks for posting your concern at HCM Melanocyl lotion and Repigmin lotion are essentially the same. Both of them contain 1% 8-Methoxypsoralen (8-MOP). It can be used either as a diluted solution OR neat depending on the advice of your dermatologist. Local application at the site of vitiligo patches should be followed sun exposure after 30 min for 1-5 min initially, which is gradually increased. The goal is to attain a faint pinkish erythema which is considered adequate sun exposure. If you experience deep erthema or pain, blisters etc it should be immediately stopped and you should immediately see your dermatologist. take care