A 23-year-old woman from Ilford has died after eating what she thought was a cannabis sweet, bought on social media.
Police have issued an urgent warning around the safety of the sweets, which are known as gummies and often presented in child-friendly packaging.
A man has since been charged with a raft of drug offences in relation to the incident.
On March 29, the woman ordered the “cannabis sweets” to her home in Ilford off a messaging app.
Police said the batch was packaged in “Trrlli Peachie O’s” branding.
The 23-year-old and a friend, 21, each ate one sweet and immediately felt unwell.
The 23-year-old woman died in hospital on Saturday.
The Met said her identity is not being released at this time.
A special post-mortem examination will be arranged in due course.
Police are also carrying out tests on sweets which were recovered.
The second woman has been discharged after hospital treatment.
Detectives are urgently trying to identify any other cases where Londoners have become seriously unwell after eating cannabis sweets, gummies and similar products.
Scotland Yard said officers are aware of one potentially linked case, in which a woman was taken unwell earlier in March after eating a cannabis sweet in Tower Hamlets.
She was taken to hospital and later discharged. Enquiries are ongoing to establish whether this sweet was part of the batch of sweets associated with the Ilford death.
A man was arrested on Friday, and has been charged with possession with intent to supply Class B synthetic cannabinoid, being concerned in the supply of a synthetic cannabinoid, and possession with intent to supply a psychoactive substance.
Ch Supt Stuart Bell, who polices Redbridge borough, said: “I must warn the public against taking any illegal substances, including those packaged in the form of cannabis sweets.
“Please do not buy or consume these products.
“They are illegal and, because of the child-friendly packaging, they can pose a risk of accidental consumption.
“The particular batch of sweets were contained in packaging featuring ‘Trrlli Peachie O’s’ branding.
“It has not been confirmed at this stage where the sweets were manufactured.
“Drug dealers harm communities and risk the safety of individuals.
“We will take positive action to target those engaged in this activity as well as those found in possession of these substances.”
Anyone with information about people selling illegal products such as these is asked to speak with local officers, call police on 101 or, to remain anonymous, contact Crimestoppers.