Before using this drug, inform your doctor about your current list of medications, over the counter products (e.g. Vitamins, herbal supplements, etc.), allergies, pre-existing diseases, and current health conditions (e.g. Pregnancy, upcoming surgery, etc.). Some health conditions may make you more susceptible to the side-effects of the drug. Take as directed by your doctor or follow the direction printed on the product insert. Dosage is based on your condition. Tell your doctor if your condition persists or worsens. Your face becomes black when you are sunlight because due to to depigmentation which is the side effect of this drug. I suggest you to drink lots of water apply raw potato and aloevera with lemon it will do wonders.