Public Health England (PHE) has issued a warning of a sharp rise in the number of overdoses linked to people using drugs in several areas across the country.

There are early signs that the overdoses may be caused by heroin mixed with a potent and dangerous synthetic opioid, but further work is needed to confirm any links between the cases.

Synthetic Opioids: Carfentanyl and Fentanyl

Fentanyl - also spelled fentanil, is a powerful opioid used as a pain medication and together with other medications for anesthesia. It's also used as a recreational drug, sometimes mixed with heroin, methamphetamine, or cocaine. It has a rapid onset and its effects generally last under two hours.

Common side effects include nausea or vomiting, constipation, sedation, confusion, and injuries related to poor coordination. Serious side effects may include decreased respiratory rate (respiratory depression), serotonin syndrome, low blood pressure, or the development of an opioid use disorder

It is around 100 times stronger than morphine, about 50 times stronger than heroin. Some fentanyl analogues such as carfentanil are up to ~10,000 times stronger than morphine.

Carfentanyl is a lipophilic chemical that can easily cross the blood-brain barrier, carfentanil has a very rapid onset of action but is shorter acting than fentanyl.

For pain relief, a unit of carfentanil is one hundred times as potent as fentanyl, five thousand times as potent as heroin, and ten thousand times as potent as morphine.

To date, there have been at least 46 poisonings resulting in 16 deaths but investigations are still ongoing. The areas affected include South London, the South East, South West, and East of England.

Heroin: Reducing the Risk

Many of the most harmful effects of heroin relate to sharing or reusing needles for injection.

Many heroin users start out smoking it, then as the addiction grows, switch to injection. Although snorting, smoking, and injecting are all dangerous, there are more serious risks associated with injection. These include contracting hepatitis and HIV through unclean needles. 

Snorting or smoking heroin doesn't have quite as instant or strong an effect, but it does reduce the risk. 

Never use heroin alone, and lower your dosage. 

However, despite as much harm minimisation as possible - heroin is an incredibly toxic drug that's easily mixed with various cutting agents. If you're struggling with heroin addiction you must consider treatment options. 

We strongly advise all drug users to get support from local drug services, as being in treatment greatly reduces the risks of harm and overdose.