The first line and by far the most common treatment today is with the prescription drug sildenafil citrate, sold under the brand name Viagra. An estimated 20 million prescriptions for the pill have been filled since it was approved by the FDA in March 1998. It is also the most effective treatment with a success rate of more than 60%. The drug boosts levels of a substance called cyclic GMP, which is responsible for widening the blood vessels of the penis. In clinical studies, Viagra produced headaches in 16% of men who took it, and other side effects included flushing, indigestion, and stuffy nose.
Chlamydia and erectile dysfunction: What's the link? Some people who have chlamydia also experience erectile dysfunction (ED), which involves problems getting or maintaining an erection. Chlamydia can infect the prostate gland, leading to prostatitis, pain, and ED. In this article, learn more about the link between this common infection and ED, and treatments for both. Read now
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.
The Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) study, designed to determine whether an individual man’s sexual outcomes after most common treatments for early-stage prostate cancer could be accurately predicted on the basis of baseline characteristics and treatment plans, found that 2 years after treatment, 177 (35%) of 511 men who underwent prostatectomy reported the ability to attain functional erections suitable for intercourse. 
#6 It’s performance anxiety. Many men suffer from performance anxiety, and that’s another reason you can’t get hard. Simply put, you’re too nervous to get your dick up. And that’s okay, it happens! This is likely to happen if you haven’t had sex in a while or if you’re starting up with a new partner. Sex is supposed to be fun, but worrying over your prowess between the sheets can make sex the exact opposite of what’s it’s supposed to be. [Read: 13 ways to overcome sexual anxiety and perform]
Stress is another factor that can be a cause or effect of ED. If you're stressed at work, at home, and in your relationships, it's going to take a toll on your sexual function. Your mind is elsewhere, and relaxing when you finally make it between the sheets is a long shot. Now you’re stressed because you can’t get it up (talk about the ultimate catch-22), so you're stuck in this sad, frustrating cycle. “ED really affects the psyche of a guy, regardless of the etiology, Gittens says. “If you have a problem getting an erection one night, you’re probably going to be anxious and worried your partner might see you as less of a man the next time you try to get an erection.” There's a pill that will help with this, and it's not promoted on television with middle-aged men in sports cars. It's a damn chill pill.
What’s important to take away from this is that, because erections can occur throughout the day for no reason, erectile dysfunction can be difficult to diagnose. Some men achieve erections for no reason, yet when provided with stimuli, they aren’t able to. Some men, on the other hand, only get aroused when directly stimulated. This means that healthcare professionals need to take into account many variables prior to diagnosing and treating erectile dysfunction.
The 4 ED medicines we prescribe – Generic sildenafil 20 mg, Viagra (also sildenafil), Cialis (Tadalafil), or Levitra (Vardenafil) - are generally safe but shouldn’t be used as recreational drugs. They’re meant to treat a medical condition and can cause serious side effects including but not limited to an erection lasting more than four hours, sudden loss of vision in one or both eyes, and sudden decrease or loss of hearing.
Can apple cider vinegar treat erectile dysfunction? Apple cider vinegar is thought to have many health benefits, but can it help treat erectile dysfunction (ED)? ED can result from cardiovascular problems, diabetes, and other factors. Apple cider vinegar may help improve symptoms of conditions related to ED. Find out how it may help, and how to use it safely. A Home-Based Walking Program Improves Erectile Dysfunction in Men With an Acute Myocardial Infarction. The American Journal of Cardiology, 115(5), 5741-575. Retrieved from http://www.ajconline.org/article/S0002-9149(14)02270-X/abstract