Yes. Marijuana could be sabotaging your manhood.
Cannabis is gaining more attention in the media and medical journals along with its legalization. Many people are touting its benefits from pain relief, anti-inflammatory and cancer fighting.
But marijuana can be a major cause of Erectile Dysfunction (ED). A study in The Journal of Sexual Medicine found THC receptors to be located in penis tissue. It appears THC can decrease the erectile function of cavernosa tissue, which is one the major tissues in the penis.
After speaking with a very experienced naturopath, he too noticed this trend in several marijuana users. So the science fits!
Other supporting studies even show chronic marijuanna users have weakened orgasms 
ED drugs are VERY
expensive, have several side effects and often are unsatisfying for some men. There are many approaches I take with male patients and each is a personalized to each man. I must use a whole, body approach because oftentimes ED is not physical but Psychological.
1. Shamloul R, Bella AJ. Impact of cannabis use on male sexual health. J Sex Med. 2011;84:971–975.
2. Johnson SD, Phelps DL, Cottler LB. The association of sexual dysfunction and substance use among a community epidemiological sample. Arch Sex Behav. 2004;33(1):55–63.