Yohimbine hydrochloride is the principal alkaloid of the bark of the African yohimbe tree. It is primarily selective for the presynaptic alpha-2 receptor that enhances the central release of norepinephrine1,2 or even epinephrine,3 although the latter is controversial.4 This central action increases sexual arousal2,5 and appears similar to the central alpha-2 adrenergic mechanism that initiates hot flashes.6 Peripherally, yohimbine may partially antagonize norepinephrine-induced contraction of corporeal cavernosal smooth muscle.7,8 The action is that of an antagonist to postjunctional alpha-2 adrenergic receptors, but a direct effect on vascular smooth muscle is also possible.9
The art of acupuncture has become the new treatment for everything from back pain, depression, and even ED. Impotence could be more of a state of mind, and acupuncture may help. Through this alternative therapy, fine needles are placed in various parts of the body to relieve pain or stress. Although there are many mixed studies for acupuncture and ED, many tend to confirm positive results. A 1999 study found acupuncture improved the quality of erection and even restored sexual activity in 39 percent of participants.
Several studies have shown that erectile dysfunction is somehow linked to problems with cardiovascular health — which one comes first has been the question. It makes sense; the penis becomes erect through a complex system of blood vessels and spongy tissue called the corpora cavernosa — this is where the blood gets trapped, causing the erection. When problems arise through this system, whether they’re caused in the brain or through problems with the blood vessels, the penis can’t get erect.

Penile implants - are generally used if physical damage (like an accident) makes the anatomical parts needed for an erection not work. These are inserted by surgery and can provide a permanent treatment choice if others fail to work. The implants can be semi-rigid or inflatable. They can be pretty expensive and are not usually available on the NHS.
We studied the involvement of zinc in the sexual behavioral response of male rats. The study design employed a rat model to predict the human sexual response to elemental zinc supplementation. Rats were used because they are very social and copulate under a variety of circumstances, regardless of the presence of a human experimenter. They are practical (small and easy to handle) and certain tissues and neuroendocrine systems are strikingly similar to humans.[13]
Yohimbine: The main component of an African tree bark, yohimbine is probably one of the most problematic of all natural remedies for ED. Some research suggests that yohimbine can improve a type of sexual dysfunction that is linked with a drug used to treat depression. However, studies have linked yohimbine to a number of side effects, which can include anxiety, increased blood pressure, and a fast, irregular heartbeat. Like all natural remedies, yohimbine should only be used after advice and under supervision from a doctor.
E.D. may just be that early warning sign. Erections depend on blood flow, and blood flow depends on nice, wide-open arteries. Atherosclerosis doesn’t just affect the arteries around your heart; if you have plaque build-up, you are likely to have it all around the arterial system — and the penile artery is one of the smallest arteries you have (no matter what you claim about your size). So if you have atherosclerosis, then the plaque there will be one of the first places where you would notice a decline in blood flow.
Geraerts, I., van Poppel, H., Devoogdt, N., de Groef, A., Fieuws, S., & van Kampen, M. (2016, January–February). Pelvic floor muscle training for erectile dysfunction and climacturia 1 year after nerve sparing radical prostatectomy: A randomized controlled trial [Abstract]. International Journal of Impotence Research, 28(1), 9–13. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/26538105
Usually there will not be a specific treatment that will lead to the improvement of erectile dysfunction. However, there are treatments that will allow erections to happen and can be used to allow sexual activity to take place. There are three main types of treatments: non-invasive treatments such as tablet medicines and external devices (e.g. vacuum device); penile injections; or for men who have not had success with other treatments, surgery may be an option.
Physical exercises are only one part of overcoming sexual dysfunctions. If you're serious about restoring full control sexually then you need to understand which of your current thoughts and actions are causing your failure. After you understand how your problem works, THEN you can apply the correct thought and action sequence to stay in control sexually!
Yohimbe supplements haven't been tested for safety and keep in mind that the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established. You can get tips on using supplements here, but if you're considering the use of Yohimbe, it is essential that you talk with your physician first. 
The results, published earlier this month, show that the 80 men in the study with moderate or severe erectile dysfunction (ED) and high cholesterol reported an improvement in their ability to maintain an erection after supplementing their diet with niacin. The 80 men who took a placebo pill, who also began the study with only mild ED, did not experience a change in their symptoms, the researchers said.
Many studies have been conducted on this topic; their results have been challenged by lack of controlled groups and non-randomization. Randomized controlled trials (RCTs) are generally accepted as the most valid method for determining the efficacy of a therapeutic intervention, because the biases associated with other experimental designs can be avoided.Non-randomized controlled trials, can detect associations between an intervention and an outcome. But they cannot rule out the possibility that the association was caused by a third factor linked to both intervention and outcome. Random allocation ensures no systematic differences between intervention groups in factors, known and unknown, that may affect outcome. Randomized controlled trials are the most rigorous way of determining whether a cause-effect relation exists between treatment and outcome and for assessing the cost effectiveness of a treatment (45, 22).
The researchers noted that "when patients were stratified according to the baseline severity of ED, the patients with moderate and severe ED who received niacin showed a significant improvement in IIEF-Q3 scores (0.56 0.96 [P = 0.037] and 1.03 1.20 [P < 0.001], respectively) and IIEF-Q4 scores (0.56 1.03 [P = 0.048] and 0.84 1.05 [P < 0.001], respectively] compared with baseline values, but not for the placebo group...For patients not receiving statins treatment, there was a significant improvement in IIEF-Q3 scores (0.47 1.16 [P = 0.004]) for the niacin group, but not for the placebo group. Niacin alone can improve the erectile function in patients suffering from moderate to severe ED and dyslipidemia." [3]
It’s important to note that high levels of zinc can reduce available copper in the body and affect iron levels. High levels of zinc can also interfere with different kinds of medications. Though it is estimated that 40 milligrams of zinc supplement are safe for men to take daily, there is no long-term research into the effects that this practice could yield.