Viagra - the facts

Libido

Viagra does not increase the libido. For some middle-aged men a loss of libido may simply be a natural part of growing older; but if you think there is some other cause, a visit to your GP and possible referral to a therapist will be of much more use than a pill. It cannot produce desire; it simply helps to make a penis erect once the desire is there.

Similar drugs to Viagra

Levitra and Cialis

These belong to the same class of drugs as Viagra, and are known as PDE-5 inhibitors. They work by relaxing the blood vessels in the penis, allowing blood to flow into it and cause an erection.

Viagra and Levitra are very similar; both are taken about an hour before sexual activity and their effects last between four and five hours.

Cialis works more quickly and lasts for longer. It becomes effective in the body after 20 minutes and remains active for 36 hours. It has been nicknamed The Weekend, because men can take it on a Friday night and still be raring to go on a Sunday morning.

Viagra effectiveness

When appropriately prescribed, the drugs generally work well. The overall success rate is about 80 per cent, although it's closer to 60 per cent in men who are impotent because of diabetes complications.

All three drugs can have similar side effects, including stomach upset, headache and facial flushing. However men prescribed nitrate-based medicines, used to treat angina, must NOT take them, as the combination could cause blood pressure to drop to an unsafe or life-threatening level. They are also risky for men with very low or uncontrolled high blood pressure.

New approaches

PT-141 is a new type of treatment undergoing trials. It differs dramatically from other drugs in that it aims to stimulate desire. Its US manufacturers are also optimistic that planned trials will show it works for women as well as men. It's taken nasally, rather than by mouth, and early research findings suggest it might be a safer option than the other drugs. If the trials prove successful it is likely to be marketed in about three years' time.

Who can get the treatment

Strict criteria surround NHS prescription of oral impotence drugs. Men are eligible only if they suffer from one of a specific list of diseases or injuries, including prostate cancer, kidney failure, diabetes, multiple sclerosis, spina bifida, Parkinson's disease and spinal cord or severe pelvic injury. NHS prescriptions are restricted to one tablet a week.

The treatment is available on private prescription but is expensive at about £9 a pill. All three drugs are sold widely on the web, with countless sites offering the pills by post.

Other options

Since 1994, men have had the option of injecting a drug called alprostadil into the penis to achieve an erection. It works by relaxing the muscles in erectile tissue, which allows blood to flow more easily into the penis. Although it is effective, unsurprisingly many men feel the cure is worse than the disease.

A system called MUSE is a less daunting prospect since the same drug is administered as a pessary via a special applicator into the urethra - the tube through which urine is discharged. Both the injection and MUSE are available on prescription from GPs.

Vacuum pumps

Vacuum pumps, either hand- or battery-operated, work by creating a vacuum around the penis and so allowing blood to flow into it. A ring is then passed over the base of the penis to prevent blood flowing out again.

Pumps work within two to three minutes, have no side effects and the resultant erection lasts for about half an hour. While some couples may dislike the mechanical preparations involved before love-making, pumps are cheap, easily available and you don't have to see a doctor to get one.