More than a dozen deaths from suspected heroin overdoses in the past two weeks across England have prompted an official warning to drug users.

There have been at least 46 poisonings resulting in 16 deaths in south London, the South East, South West and East of England, Public Health England (PHE) said.

Investigations are ongoing but the health body said most of the cases had happened in the past 10-14 days.

PHE said there are early signs that the overdoses might have been caused by heroin mixed with a potent and dangerous synthetic opioid, but it is carrying out more work before it can confirm any links between the cases.

The organisation said it is “urgently investigating” alongside the National Police Chiefs’ Council (NPCC) and National Crime Agency (NCA) and will work to prevent further deaths.

PHE has issued an alert to all local public health and drug services, making them aware of the problem and asking them to reach out to drug users outside of the drug treatment system.

Rosanna O’Connor, PHE’s director of drugs, alcohol, tobacco and justice, said: “We are urging drug users to be extra careful following reports of a sharp rise in the number of overdoses potentially connected to heroin, tragically with some deaths.

“We are urgently investigating with the police and local partners.

“We strongly advise anyone using drugs not to use alone and to test a small amount first.”

She said people need to be aware of the signs of an opioid overdose, namely shallow breathing, loss of consciousness and blue lips or fingertips, and to act fast by calling an ambulance immediately and using the opioid antidote, naloxone, if available.

NCA deputy director Miles Bonfield said: “The National Crime Agency is leading and co-ordinating the law enforcement response to the drug overdose incidents, working closely with the National Police Chiefs’ Council, Public Health England and others, to gather intelligence and assess the situation.

“Drug dealers pose a serious threat to our communities, as they exploit vulnerable people for their own gain. As always, our primary objective is to protect lives and we are working hard with our partners to minimise harm.

“I would urge people to take the time to read the official advice from Public Health England so you know the risks and signs to look out for and if you are offered drugs, report it to your local police.”

NPCC drugs co-ordinator lead Mark Lay said there is nothing at present to suggest a direct link between any of the areas affected.

He said: “Drug dealers target and exploit some of the most vulnerable people in society. Forces are working at pace with local partners to ensure that such communities are being informed of the risks, and the dangers of drug and substance abuse.

“As always, I would urge anyone who is offered drugs to contact their local force with any information which might help the police to find those responsible and get dangerous drugs off the streets. “

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