Erectile dysfunction, also known as impotence, is the inability to get and maintain an erection.
According to the NHS, it is a common condition, particularly in older men and those living in London.
It is thought half of all men between 40 and 70 years will have it to some degree.
There are a range of causes for erectile dysfunction, including psychological and physical.
It can be a sign of a health condition, like high blood pressure, high cholesterol or diabetes.
Additionally it may be down to hormonal issues, and surgery or injury.
Here are three harmless reasons you can’t maintain an erection during sex.
Drinking too much alcohol could cause erectile dysfunction.
It is a depressant on your central nervous system, which decreases blood flow to your penis.
Sticking to the UK Chief Medical Officer’s recommendation of no more than 14 units per week could help.
The University of Maryland have identified a number of medications that can cause erectile dysfunction.
These include high blood pressure medications, beta-blockers and diuretics.
Depressants can also interfere, and a Stanford University study found that 75 per cent of depressed patients experience a fall in libido.
Psychological causes like stress about work or relationships could be another reason.
According to a study published in the journal Hormones and Behaviour it can raise levels off the stress hormone cortisol which can block the effects of testosterone.
This can interfere with libido and cause problems with erection.
However, according to the NHS, erectile dysfunction can also be caused by more serious psychological problems like anxiety, depression and relationship problems, and for these you should eek professional help.