Erectile dysfunction, or impotence, is defined by the National Institute of Health as: "the persistent or recurrent inability to attain or maintain an erection sufficient for sexual intercourse." Erectile dysfunction is a common problem which is thought to affect at least one in ten men over the age of 21 - that's an estimated 2.3m men in the UK alone.
Until about 20 years ago, erectile dysfunction was considered to be a purely psychological problem, but research now suggests that physical problems are present in about 75% of sufferers. However, the majority of men with erectile dysfunction experience a combination of psychological and physical causes, ranging from diseases like diabetes, kidney failure and high cholesterol, to stress, anxiety and depression.