Narcan also saved the lives of 18 heroin abusers in April.

Tayside Police’s drugs co-ordinator, Detective Inspector Wendy Symington, said, “It’s worrying and we are lucky that more people have not died.

“We are concerned about the number of non-fatal overdoses that have occurred over the last few months. In many cases, if medical assistance had not been administered, these would have been drugs deaths, numbers of which are increasing in Tayside annually.”

A shot in the arm can save a drug abuser’s life because Narcan reverses the symptoms produced by narcotic drugs, such as difficulty breathing and coma.

It’s injected into the muscle tissue of the upper arm and is quickly released into the bloodstream.

When users take too much of any opiate, they nod off, and from one to three hours later lose the will to breathe.

When Narcan is administered, it removes the heroin from their receptors and links onto the receptors themselves and blocks the drug’s effects for 30 to 90 minutes.

Victims should still go to hospital, but those 30 to 90 minutes are enough to save someone’s life.

Inspector Symington said, “Narcan is an opioid antidote which can reverse the effects of an overdose if used quickly, but it is very important people are aware of their responsibilities in an emergency.

“The emergency services must be called, even if you think the person has recovered.

“If the person is unconscious, they should be put in the recovery position before help arrives. Give them the best chance to survive. Pouring cold water on the person or slapping them to bring them round is a myth — it does not work.

“People have to understand that if illegal, controlled or prescription drugs are taken in excessive amounts, there is a real possibility that overdose will occur or in the worst scenario, death.

“Tayside Police work very closely with other statutory and voluntary agencies to try to reduce the harm that drug misuse causes, harm that clearly impacts upon drug misusers themselves, their families and communities within Tayside.

“Overdose-prevention training is being cascaded throughout Tayside, which aims to reduce the incidence of fatal and non-fatal overdose.”

Inspector Symington revealed that 100 overdoses of controlled, prescription and illegal drugs occurred between February and April.

“Remember these are only the ones we hear about or attend — there will be others,” she said.

At least 17 people have died of suspected drugs overdoses in Dundee since the turn of the year, with heroin a factor in most cases.

Statistics covering the period between 1997 and 2006 show a 17% increase in drug-related fatalities in Tayside, a period which has coincided with huge increases in the purity of street heroin.

Some has been as high as 64% pure, exposing users to risk of overdose.

A survey of heroin users in Dundee, published earlier this year, found most were taking the drug daily and spending an average of £18,000 a year to feed their habit.