In July alone, synthetic cannabis has been blamed for a spate of Auckland deaths.

A 31-year-old woman found dead at a west Auckland address was believed to have been smoking synthetic cannabis, police say.

Her death, in the suburb of Kelston, is the ninth thought to have been linked to synthetic cannabis use in Auckland in the past month.

Emergency departments around the region said they had seen a spike in patients who had used the psychoactive substance.

SUPPLIED Auckland teenager Devonte Pierce died earlier in July. Police believe his death may also have been linked to synthetic cannabis use.

Many were suffering hallucinations and seizures leading to cardiac arrest.

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Acting Detective Inspector Peter Florence said the public could be assured police were taking synthetic cannabis harm "very seriously".

"We are doing everything we can to get synthetic cannabis off our streets.

"Police officers across the country are conducting search warrants and seizing synthetic cannabis and we are continuing to put suppliers and manufacturers before the courts."

On Thursday, police arrested two people in St Lukes who had up to three kilograms of the illegal drug.

They had been charged with possession for supply, he said.

Earlier this week police also seized 50 bags of the drug from a Ranui address in west Auckland while another operation in Avondale resulted in 12 arrests.

Although the Kelston woman may have been smoking synthetic cannabis a short time before her death, there may have been other contributing factors, police said.

The matter has been referred to the Coroner who will ultimately determine the cause of death.

Earlier in July Chief Coroner Judge Deborah Marshall issued a health warning over escalating synthetic cannabis harm.

"I've also been advised by St John that there have been a significant number of non-fatal cases where people have been hospitalised after using the drug, which is known to cause potentially fatal seizures," she said.

"While the police and coronial investigations are still at an early stage, and the final causes of death have yet to be established, the number of cases where synthetic cannabis appear to have been a contributing factor has prompted me to issue this public warning."

People can contact their local police station with information about synthetic cannabis sale or they can provide information anonymously to Crimestoppers on 0800 555 111.

"This is causing harm to our community, and we urge those smoking synthetic cannabis to stop immediately and seek help," Detective Inspector Florence said.