According to the Sexual Advice Association¹, there is a combination of both physical and psychological factors as outlined below:

Physical (on the body):

• The narrowing of blood vessels to the penis – Causes can include high blood pressure, high cholesterol and diabetes
• Conditions that affect the nervous system – including Multiple Sclerosis (MS), Parkinson’s disease, stroke, diabetes and spinal injury or disorder
• Hormonal problems – including under or overactive thyroid, a low testosterone level
• Surgery and radiation therapy for the bladder, prostate or rectal cancer
• Injury to the penis
• Excessive alcohol consumption
• Side effects of prescribed medication – including diuretics (tablets that make you pee), some types of drugs taken for blood pressure, beta-blockers (slows down the heart), anti-depressant medication and anti-epileptic medication.

Psychological (in the mind):

• Depression
• Suffering stress and anxiety at work or home
• The person’s partner has sexual problems
• Relationship problems due to stress, poor communication or other problems
• Lack of self-confidence having failed before with ED and the fear of it happening again
• Worried about sexual orientation
• Suffered sexual abuse previously
• Having no desire for sex

ED is more likely to occur with people that do not follow a healthy lifestyle for example: smokers, being overweight and those that are not physically active/get enough activity.

^{1 https://sexualadviceassociation.co.uk/erectile-dysfunction/}