Meta-analysis of 98 studies has identified 37 different risk factors.[1] Men who are obese (BMI of over 30) are three times more likely to have ED[2] and there is emerging evidence that Covid-19 infections can lead to erection problems.[3]

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.[4]

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.[5]

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.[6]

In men under 40, ED is most commonly caused by psychological issues including anxiety, depression, inhibited sexual desire and excessive use of pornography.[7]

The Kinsey Institute identified PIED — pornography-induced erectile dysfunction — as a problem in 2007[8] and consumer surveys show 67% of men with ED believe pornography puts them under pressure to perform sexually.[9]

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.[1]

Neurological conditions including Parkinson’s disease and multiple sclerosis can also cause ED.[2]