People who regularly use cocaine could be causing serious damage to their hearts, experts have warned.
Cocaine damages the heart
It follows a study by Professor John Henry of Imperial College London, one of the country's leading drugs experts.
He found that one in three young men who turned up at one of the biggest A&E units in the capital with chest pains had been taking cocaine.
He said many cocaine users were unaware of the serious health risks associated with taking the drug.
Professor Henry carried out anonymous urine tests on 450 men under the age of 30 who turned up at the A&E department at St Mary's Hospital in Hospital with chest pains.
One in three tested positive for cocaine, according to a report in the Daily Mail newspaper.
"This is a lower rate than some American studies have found but higher than we expected and very worrying," he said.
The study is expected to be published in a medical journal later this year.
A growing number of young people are regularly using cocaine. This has been partly fuelled by the drop in its price in recent years.
Seven years ago, a gram of cocaine cost around £70. Now, a gram costs around £40.
Latest figures from the British Crime Survey show that cocaine usage jumped by 30% in a year.
Deaths from cocaine have also increased - up from 18 in 1996 to 95 last year.
Professor Henry said many cocaine users are unaware of the health risks.
"The public image it has is of being something recreational and mild, which is very far from the truth."
Cocaine triggers a high by increasing levels of dopamine in the brain.
Pressure on heart
However, it also puts massive pressure on the heart.
Doctors say they are seeing an increasing number of young people whose hearts resemble those of people twice their age.
Mr John Heyworth of the British Association of Accident and Emergency Medicine described Professor Henry's findings as worrying.
"Cocaine is often seen as being glamorous but nobody mentions the risk of heart attack, particularly among young men in their 20s and 30s.
"This is an important and alarming study and demonstrates the scale of the problem."
Mr Don MacKechnie, chairman of the BMA's A&E
committee, said people should be aware of the risks.
"It can be fatal. Young people die from taking cocaine, the same as they do from any other recreational drug.
"I think people have to be aware of that. If you gamble be prepared for that eventuality."
Harry Shapiro from the UK charity DrugScope said physical damage came with prolonged regular use of cocaine.
"In order to keep the effects of cocaine going, it needs to be taken repeatedly.
"This can put a strain on the heart and blood pressure will go up," he told BBC News Online.
"If you have any medical problem, even one you are unaware of, this could cause difficulties."
Mr Shapiro said the drug can also lead to psychological problems.
"When people stop taking cocaine after a weekend, they can feel terribly depressed. For many people, this depression can be profound."