Poisoning from synthetic or semisynthetic substances in puff bars, gummies, and e-cigarettes is on the rise. The Danish health authority has issued a new warning after several young Danes were hospitalised – similar poisonings were reported in Sweden.

In the past year, the Danish Health Authority has issued multiple public warnings that the use of disposable puff bars or e-cigarettes containing synthetic or semisynthetic cannabinoids could lead to poisoning, as they may be more harmful to humans than organic cannabis.

Since 2024, Denmark has banned the use, possession, and sale of such products if they contain sweet flavours or exceed legal nicotine levels. Despite the attention, in early 2025, the Danish media reported several new hospital admissions among young people.

Five people aged between 16 and 18 had to be taken to the hospital after smoking puff bars in Tønder in January. The Danish Health Authority has since issued a new warning.

“Every young person who takes drugs is one too many. You shouldn’t be fooled by the fact that the products come in pretty packaging, and now we’re also seeing drug traffickers putting drugs in them,” Maja Bæksgaard Jørgensen, head of section at the Danish Health Authority, told Euractiv.

She warned that there is a black market, particularly online.

Semisynthetic cannabinoids

A total of six cases were reported at Danish hospitals in January 2025, Dorte Fris Palmqvist, an anaesthetist and consultant at Bispebjerg Hospital in Copenhagen who works for the Danish Poison Control Hotline, which covers Denmark, Greenland, and the Faroe Islands, told Euractiv.

“[They] were not just from puff bars. The synthetic and semisynthetic cannabinoids can also be eaten, for example, in a cake or smoked like cannabis,” she said.

A puff bar has become a slang term for e-cigarettes or vapes, borrowed from a brand with the same name.

Semisynthetic cannabinoids that were not covered by international drug conventions began to appear on the European drugs market in 2022. The first substance identified was hexahydrocannabinol (HHC) in May 2022.

In Denmark, doctors saw the first poisoning in late 2023.

“Our first patient who had ingested a semisynthetic cannabinoid and developed severe symptoms requiring hospitalisation [was] in the autumn of 2023. Since then, we have seen an increase in enquiries to Poison Control regarding semisynthetic and synthetic cannabinoids,” Dorte Fris Palmqvist said.

The calls to Poison Control came both from healthcare workers, mostly hospital doctors, and members of the public.

In 2024, the number of calls about poisonings had risen to 75, of which 57 were about people under 18. Another 97 calls concerned symptoms from smoking e-cigarettes, she said. 

Nicotine products

Sweden’s Poisons Information Centre has experienced a rise in enquiries about poisonings from nicotine products containing especially semisynthetic cannabinoids from 2022 to 2024.

The number of calls from hospital doctors alone increased from 1 in 2022 to 84 in 2023 and 88 in 2024.

“In early 2025, we have so far registered seven reports of poisoning by semisynthetic cannabinoids, of which two were from hospitals regarding patients,” Aza Kader, a pharmacist at the Centre, told Euractiv.

In cases where the Poisons Information Centre has been involved, the symptoms have often been similar to those of organic cannabis (THC) use.

“However, patients have often presented with more severe and prolonged symptoms, mainly anxiety, worry and lethargy. When smoking, symptoms usually resolve within 4-6 hours but occasionally last up to 12 hours. When ingested, however, the symptoms are much more prolonged – some patients have experienced prolonged loss of consciousness with symptoms persisting for up to four days after eating sweets,” Kader said.

No antidote

Meanwhile, he also explained that there is no antidote for poisoning from synthetic or semisynthetic cannabinoids, so hospitals can only treat the symptoms.

Many products contain synthetic or semisynthetic cannabinoids, but not all are forbidden to sell in Sweden.

“The substances are structurally similar to THC, the psychoactive component of cannabis, but small changes in their molecular structure mean that several of them are not yet classified as narcotic drugs and are gradually being classified. They are most commonly sold as vapes/e-cigarettes or as candy,” Aza Kader said.

Pan-EU problem

Cases of intoxication or psychosis requiring hospitalisation after smoking vapes containing synthetic or semisynthetic cannabinoids have also been reported from France, Ireland and the United Kingdom.

The EU Drugs Agency, EUDA, is stepping up its work to identify new potent substances.

Its current EU Early Warning System (EWS) will be supplemented by a European Drug Alert System (EDAS) and a European Threat Assessment System (ETAS), which is planned to be fully operational in 2025, according to the agency’s recently published work programme.

“These systems will enhance timely health and security risk communications, with several pilot threat assessment exercises planned for this year,” the EU agency said.

[Edited by Vasiliki Angouridi, Brian Maguire]