Both ED and low testosterone (hypogonadism) increase with age. The incidence of the latter is 40% in men aged 45 years and older.  Testosterone is known to be important in mood, cognition, vitality, bone health, and muscle and fat composition. It also plays a key role in sexual dysfunction (eg, low libido, poor erection quality, ejaculatory or orgasmic dysfunction, reduced spontaneous erections, or reduced sexual activity). 
It may also become a treatment for anemia, bone density and strength problems. In a 2017 study published in the journal of the American Medical Association (JAMA), testosterone treatments corrected anemia in older men with low testosterone levels better than a placebo. Another 2017 study published in JAMA found that older men with low testosterone had increased bone strength and density after treatment when compared with a placebo.
For some men who are aging, the idea of testosterone replacement therapy seems like an enticing option. Effects such as increased vigour, increased muscle strength, enhanced memory, sharpened concentration, a boost in libido and increased energy levels can make this drug seem like the miracle anti-aging therapy. However, it is unclear whether or not this therapy can offer any health benefits to men who simply have a normal age-related decline in testosterone. Few large studies have examined the effects of this therapy in men who have a healthy testosterone level and the few smaller studies that have been conducted reveal conflicting results.
There are treatments available to help you to get and maintain an erection. In addition, making healthy changes to your lifestyle could help with impotence. Switching to a healthier balanced diet, taking more exercise and cutting down on or giving up alcohol and cigarettes could help you to see an improvement in sexual function. If you think that the problem may be related to stress or anxiety, counselling can also help.
When I first started TRT, my physician prescribed a cream that you rub into your skin. The cream version of TRT is not too convenient, because if someone touches you while you have the cream on, the testosterone can rub off on him/her. This can be really bad around kids or pregnant women. If you’re sleeping next to someone, the cream can get on the sheets and transfer over that way, too. The cream can be annoying, but it works. There’s also a gel version called AndroGel; I skipped it because it doesn’t absorb as well as the cream does.