Hello, Thanks for asking your question here. I am Dr Alok Sinha, MD Psychiatry, from India. I will try my best to answer your query. Marijuana (cannabis) is a very commonly abused drug. Recent reasearches have prooved that long term use of cannabis causes permanent changes in brain (shrinkage in brain volume) as well as serious mental illness like psychosis, anxiety, depression and deficit in higher mental functions. These effects usually become visible after10 years of regular use. Although you claim consuming it once or twice but our experience says that sooner or later an occasional drug abuser becomes daily abuser. Secondly the changes in brain and the nature of mental illness is permanent. Although Marijuana does not cause impotency per se but it may cause various kinds of psychiatric problems including other sexual dysfunctions. Are you ready to take chance at the cost of your mental health? Certainly not. So, I suggest you to quit this habit at the earliest and live a drug free life. Hope this answers your query. All the best.