The police have warned that one hit or pull could leave users in hospital fighting for their lives.
At least 14 people were hospitalised after smoking it over the weekend, the police said.
They include young adults and school children. They were hospitalised since Sunday after they smoked the unknown substance.
The substance is packaged in a small black bag and found mainly in Pretoria West, Pretoria Gardens, Daspoort and Hercules.
“What is most alarming is that the product is accessible over the counter at tobacco shops, tuck shops and adult shops. It is then mixed with cigarette tobacco or rolled on its own,” Tshwane West SAPS cluster spokesperson Captain Augustinah Selepe said.
On Monday afternoon, three teenagers from Pretoria West had to be rushed to hospital after smoking the substance. BestCare emergency services spokesperson Xander Loubser said three teens were in a serious condition and were treated for symptoms including seizures, psychosis, nausea, vomiting and hallucinations.
Various government departments have been contacted to look into the matter.
Parents are urged to speak to their children about the risks of using any type of drug, whether legal or not.