Viagra is being used by young people in British nightclubs in potentially lethal combination with cocaine, Ecstasy, and other illegal drugs, researchers said.

"The recreational use of Viagra by apparently healthy women and men is now occurring in Britain," Judith Aldridge and Fiona Measham, senior researchers at the University of Manchester, said in a letter posted on The British Medical Journal Internet site.

Aldridge and Measham interviewed young adults at nightclubs in northern England within weeks of the launch of the drug in Britain in 1998. Customers and staff said the triangular blue pills made by the U.S. pharmaceutical company Pfizer were readily available for 10 pounds (US$16) for a 50 mg tablet. Most of the men and women who admitted taking Viagra used it simultaneously with other drugs and alcohol.

"Of particular concern is the combination use of Viagra with amyl nitrite ('poppers'), both of which dilate blood vessels, and can result in a dangerous drop in blood pressure potentially causing heart attack or stroke," the researchers said.

All of the people who admitted using Viagra reported positive effects: enhanced sexual desire and lovemaking, and feelings of warmth. They got the drug from friends, partners, dealers, sex shops, or via the Internet.

Ironically, the drug is not as freely available for many impotent men who need it. Fearful that demand could bankrupt the country's government-funded National Health Service (NHS), Health Secretary Frank Dobson issued proposals suggesting Viagra should only be prescribed in the NHS system for men whose impotence is caused by a physical condition.

The move infuriated doctors who said the policy was unacceptable and unethical. The British Medical Association advised doctors to defy the government and prescribe the drug to patients who would benefit from it.

Earlier in 1999, a British urologist warned that misuse of Viagra as an aphrodisiac to improve sexual performance could cause prolonged erections that could lead to permanent impotence.