Suggest Treatment For Dry Penis Tip

Hello, I'm using Accutane for my acnes about 3 weeks now. The thing is aside from the lip dryness, I have a blood red uretha and when I walk my penis tip sticks to my boxers which causes pain. It seems very dry, I used normal creams but didn't work. I use 50 mg everyday, and 19 years old male. While urinating I don't have any pain but I don't know what to do with my dry penis tip.Thank you for your answer..