Thanks for consulting at my virtual clinic. I have carefully worked through your case, and I can realize your health worries. Being your physician, I assure you not to worry as I will take care all of your medical concerns. Alopecia may be due to a variety of cause. For males it is mostly related to male hormone testosterone. Marijuana does not prevent alopecia. consult a near by dermatologist or Trichologists who could help you with the diagnosis of the cause of alopecia and treatment of alopecia. lots of good treatments are available to reduce you hair loss and also to bring back the fallen hairs. Hope it helps. If you need further, detailed and quick assistance related to any health issues in future, feel free to ask me a question directly from my profile. Have a wonderful time ahead. Best Regards! Dr. Arunmozhi varman