In addition to these factors
diabetes, blockage of the blood vessels, and adverse effects from medications, both prescribed and recreational (marijuana and cocaine) may all play roles in sexual functioning. Disease states such as hypertension, diabetes, heart disease, and obesity can affect the blood flow into the penis. Blockage in any of the major arteries feeding the blood supply to the penis can lead to inability to obtain and maintain an erection. Diabetes, for example, this can also affect the mechanism of erection and cause ejaculatory disorders such as backward ejaculation of the fluid to the bladder instead of out of the tip of the penis at the time of orgasm.

Medications that are often identified as causes of erectile disorder which include medications used to treat depression, blood pressure lowering medications, cholesterol medications, and drugs used to treat prostate cancer.  Excessive alcohol use is the most common substance that can lead to ED, though cocaine, heroin, and marijuana have all been linked as well.