However, its popularity has waned in the past year as increasing numbers of users have discovered the tablets are often adulterated with other drugs and substances as diverse as fish-tank cleaning powder and dog worming pills.
Ecstasy, or MDMA as it is known in its pure form, first appeared in British clubs in the summer of 1989. For recreational users, it was the dream drug, producing a mild, euphoric "rush", together with feelings of exhilaration, for only pounds 10 to pounds 20 per tablet.
At higher doses, ecstasy triggered hallucinations which enhanced the frenzied atmos- phere of raves.
But the falling reliability and cost of the drug has caused many clubbers to opt for cheaper alternatives.
Amphetamine or "speed" is now more popular than ecstasy, according to drug workers, largely because a pounds 10, one-gram bag can last a week, compared to the 10-hour buzz of an ecstasy tablet.
LSD, at about pounds 2 a tablet or blotter, is also far cheaper. Both of the drugs are also more reliable.
About 90 per cent of the tablets come from the Netherlands. Drug experts believe that, because of the tighter Dutch quality controls, many suppliers sell their adulterated and low quality pills to the United Kingdom.
In the Netherlands, users can have their tablets analysed and tested for purity by street agencies and in some night clubs. The Dutch government believes this helps identify any contaminated and dangerous batches, news of which quickly spreads among drug users.
The makers often mix LSD or amphetamine into ecstasy tablets, although caffeine and tiny quantities of heroin have also been found.
The side-effects range from raging thirst and raised body temperature to convulsions, collapse and death.
Since 1990, there have been more than 50 ecstasy-related deaths, although drug workers point out that this is a low number compared to the hundreds of thousands of people who take the drug.
In 46 of the 50 fatalities, heatstroke was to blame. This is largely because the drug allows people to exert themselves for a long time without rest and without fluid. Some long-term users suffer depression, panic attacks, mental breakdown and possibly schizophrenia.
The manufacturers of ecstasy have maintained a grip on the market by producing different names for their drug, although the tablets all contain similar ingredients.
The tablets that are sold under the name of "Doves" have an indentation shaped like a dove. Tablets are also sold in different colours - there are white "Love Doves", black and red "Denis the Menace" tablets, "Pink Cadillacs" and "Disco Biscuits".
The tablets that are believed to have been taken by the three teenagers in Blackpool were called "Brown Doves".
Few drug workers have heard of this make before, although one user said that she had bought one from Manchester recently and it had a mild effect.