Stiffy Solution: The good news is, almost all of these conditions can be successfully treated if you catch them early on. And since erectile problems may be the first side effect your dude has experienced, seeking medical treatment for his erectile problems may be the thing to get him into a doctor's office. So if your dude is a well-rested, non-drinking, non-smoking, paragon of relaxation who suddenly can't get wood, urge him to talk to his doctor — his misbehaving penis may actually be communicating something way more important than "Not tonight, honey."
Another study compared the response of surgically and medically castrated rabbits to vardenafil with that of control rabbits.  Castrated rabbits did not respond to vardenafil, whereas noncastrated rabbits did respond appropriately. This result suggests that a minimum amount of testosterone is necessary for PDE5 inhibitors to produce an erection.
Patient can inject medications directly into the corpora cavernosa to help attain and maintain erections. Medications such as papaverine hydrochloride, phentolamine, and prostaglandin E1 (alprostadil) can be used alone or in combinations to attain erections. All of these medications are vasodilators and work by increasing blood flow into the penis. Prostaglandin E1 (Caverject, Edex) is easier to obtain; however, it is associated with penile pain in some individuals. The use of combinations of two or three of these medications can decrease the risk of having penile pain.
In some cases, nocturnal penile tumescence testing is performed to find out whether the man has erections while asleep. Healthy men usually have about four or five erections throughout the night. The man applies a device to the penis called a Rigiscan before going to bed at night, and the device can determine whether he has had erections. (If a man is able to have normal erections at night, this suggests a psychological cause for his impotence.)
However, in contrast, a recent systematic review of published studies, the authors concluded that overall, the addition of testosterone to PDE-5 inhibitors might benefit patients with ED associated with testosterone levels of less than 300 ng/dL (10.4 nmol/L) who failed monotherapy.  A limitation of existing studies are their heterogeneous nature and methodological drawbacks.
Thanks to over a decade of primetime television commercials, most of us can name at least one drug that treats erectile problems. However, far fewer of us can name drugs that may actually cause the problem. In reality, MedlinePlus reported that there are far more of these, and even common drugs such those to treat depression and heartburn can make it difficult to get an erection.
Christine graduated from San Francisco State University with a BA in English Literature. Shortly after she completed a Post Baccalaureate certificate in Pre-health professions and started her journey in healthcare! Christine is currently completing her Master of Science in Health Care Administration at California State University East Bay and will graduate in June of 2018. She has prior experience working and volunteering in various hospital and health care settings including nephrology, post-surgery geriatrics, cardiac electrophysiology, and orthopedics. Christine is excited to be a part of the Lemonaid team and contributing towards their mission of providing accessible health care to all. On her spare time Christine enjoys running, Olympic lifting, and visiting all of the national parks in the United States!
It appears that testosterone has NOS-independent pathways as well. In one study, castrated rats were implanted with testosterone pellets and then divided into a group that received an NOS inhibitor (L-nitro-L-arginine methyl ester [L-NAME]) and a control group that received no enzyme.  The castrated rats that were given testosterone pellets and L-NAME still had partial erections, a result suggesting the presence of a pathway independent of NOS activity.
In some cases, ED can be a warning sign of more serious disease. One study suggests ED is a strong predictor of heart attack, stroke, and death from cardiovascular disease. The researchers say all men diagnosed with ED should be evaluated for cardiovascular disease. This does not mean every man with ED will develop heart disease, or that every man with heart disease has ED, but patients should be aware of the link.