Meta-analysis of 98 studies has identified 37 different risk factors. Men who are obese (BMI of over 30) are three times more likely to have ED and there is emerging evidence that Covid-19 infections can lead to erection problems.
In men over the age of 40 there is usually a physiological cause, most commonly around blood flow to the penis. Common reasons for this include cardiovascular disease, atherosclerosis, high cholesterol, hypertension, diabetes and smoking.
Low testosterone is another recognised cause or contributing factor. Hypogonadism affects 8% of men aged 50 to 79 and it also increases the risk of CVD.
Lifestyle factors associated with chronic inflammation — such as smoking, lack of physical activity, unhealthy diets, excess alcohol, metabolic syndrome and obesity — are believed to contribute to ED by reducing nitric oxide (NO) availability.
In men under 40, ED is most commonly caused by psychological issues including anxiety, depression, inhibited sexual desire and excessive use of pornography.
The Kinsey Institute identified PIED — pornography-induced erectile dysfunction — as a problem in 2007 and consumer surveys show 67% of men with ED believe pornography puts them under pressure to perform sexually.
ED can also occur as a side-effect of prescription medicines including beta blockers, SSRI and tricyclic antidepressants, LHRH analogues used to treat some cancers, and histamine H2-receptor antagonists used to treat duodenal ulcers.
Neurological conditions including Parkinson’s disease and multiple sclerosis can also cause ED.