NSW Health is warning the community about the dangers of nitazenes following the hospitalisation of two people in NSW with severe opioid overdoses.

The two people suffered severe opioid overdoses after taking what they believed to be oxycodone tablets.

The fake oxycodone tablets have been described as yellow unmarked round tablets, sold as ‘OxyContin 40 mg’.

Nitazenes are extremely potent synthetic opioids which are more likely to decrease or stop breathing than other opioids.

NSW Poisons Information Centre Medical Director Dr Darren Roberts said these drugs are extremely dangerous, as they can be hundreds of times more potent than oxycodone and can cause severe overdose or death.

“Nitazenes are extremely potent and can vary widely in their strength," Dr Roberts said.

“As they are illicit and unregulated, there is no way of knowing what type of nitazene is present or what dosage is being taken. The strength and contents can vary widely, even within the same batch.

“It is extremely important that people recognise the signs of an opioid overdose.

“Opioids can cause pin-point pupils, drowsiness, loss of consciousness, slowed breathing/snoring and skin turning blue/grey, and can be life-threatening.

Nitazenes have been detected in vapes and in fake tablets, such as benzodiazepines, and in drugs thought to be heroin or MDMA.

“It's strongly recommended that anyone who uses illicit drugs carry naloxone," Dr Roberts said.

Take home naloxone is a life saving treatment which can temporarily reverse an opioid overdose, including with nitazenes.

Nitazenes can last longer in the body than oxycodone, heroin and naloxone. Higher and repeated doses of naloxone may be required as well as hospital treatment.

Anyone who uses naloxone should call Triple Zero (000) for an Ambulance immediately after use for follow up care. You won't get into trouble for seeking medical care. If you feel unwell, or if your friend feels unwell, do something about it.

Take home naloxone is available as an easy-to-use nasal spray or injection from some pharmacies and other health services. For more information on the take-home naloxone program visit: Your Room - Naloxone.

Naloxone is available from the NUAA via mail in a discreet package. Order via their online shop or call (02) 9171 6650.

Anyone who has concerns about adverse effects from drugs should contact the NSW Poisons Information Centre on 13 11 26, at any time 24/7.

For support and information on drug and alcohol problems, contact the Alcohol and Drug Information Service on 1800 250 015. This is a 24/7 service offering confidential and anonymous telephone counselling and information.

NSW public drug warnings are available at Public drug warnings.