Viagra is the best known one and other brands include tadalafil (brand name Cialis) and vardenafil (Levitra).
Before taking the tablets, men in the clinical trials had said their quality of life and relationships were "relatively good", but there were issues with sexual satisfaction.
Many of these men also had depression symptoms and felt low, the website reports.
While the medication did generally increase the men's satisfaction and self-esteem, they didn't report an improvement in their overall life satisfaction or their overall relationship satisfaction.
Experts say the study, published in the Journal of Sexual Medicine, highlights the need to highlight psychological issues, and not just the mechanics.
Dr Andrew Kramer, a urologist at the University of Maryland Medical Centre, told LiveScience: "It's simplistic to think that fixing an erection issue would solve relationship issues. Happiness is very complicated, and erections are just one small piece of it... a lot of couples still need additional therapy."
The research paper added that there is "growing evidence that the negative effects of erectile dysfunction extend beyond the inability to have sex, and impact men's emotional and psychological well-being.
"Treatments that target both physical and psychosocial aspects of ED are likely to be the most effective treatments for men with ED," the study said.
Though erectile dysfunction is more common in older men - around 65 per cent of the over-60s suffer from it - around 40 per cent of men will have suffered from the problem by the age of 40.
There are many physical causes for it, explains Dr Arun Ghosh, a GP specialising in sexual health at the Spire Liverpool Hospital.
It can be caused by nerve damage from diabetes, or surgery for prostate cancer.
Another cause is reduced blood flow due to smoking, raised cholesterol levels or high blood pressure. Common medications such as anti-depressants and blood pressure tablets can also hamper performance, as can stress and even regular cycling.
Dr Ghosh says the problem is also closely bound up with flagging libido: 'A lot of these men are suffering from testosterone deficiency syndrome, due to reaching their 40s and putting on weight around the stomach.
'This causes testosterone levels to drop, resulting in a loss of libido and erectile function. It's worth asking for a blood test if you hit 40 and start developing these symptoms.'
How does Viagra work?
Viagra helps by elevating the levels of the chemical that causes the tissues in the body to relax.
The effects on erectile function were discovered accidentally - it was originally developed to improve blood supply to the heart in angina sufferers.
It is prescribed for patients such as Mr Aziz, who have restricted blood flow, because it's artery-widening properties mean blood can get to the muscles that need it.
However its effect on the arteries can also have negative effects: patients who take the drug may suffer from flushed skin. It can also cause headaches and nausea.
As well as the problem of mechanics, there is a psychological component to erectile dysfunction. "If you've had a problem even once before, then you're always going to be worried it will happen again," explains Dr Ghosh.
"In fact, one of the main roles of any treatment is to give men a psychological boost. It's vitally important to use treatment alongside some kind of sexual counselling or therapy, even if the cause is due to something physical such as diabetes.
"A man's partner will often say: 'Don't worry about it' - but even if he's trying not to think about his performance, he will think about not thinking about it. And before you know it, performance anxiety has kicked in.
"Anxiety and stress stop the pituitary gland secreting the hormones needed for sex. The body goes into 'fight or flight' mode, shutting down all non-essential functions - with sex being one of them."
- DAILY MAIL
