Does practicing masturbation due to obsessive-compulsive disorder make a person impure, knowing that there is a treatment for OCD that takes time to show its effect, and that he cannot purify himself repeatedly to avoid illness and affecting his studies and psychological state?

We ask Allah to grant you healing. You must resist the whispers and thoughts to avoid the forbidden masturbation. Seek help through supplication (du'a), fasting, and both lawful and physical remedies. If you are unable to resist and are overcome by the act, then there is no sin upon you. You must perform ghusl (ritual bath) every time semen, which necessitates ghusl, is discharged. Prayer is not permissible until after ghusl. If you fear harm from performing ghusl, then wash the parts of your body that will not be harmed by washing, and perform tayammum (dry ablution) for the remainder.