A new synthetic drug makes people feel “superhuman” and has led to a series of dangerous incidents, United States police are warning.

Known as flakka, its effects include hallucinations, rage, delirium, paranoia and a sharp rise in body temperature which leads users to take off their clothes.

One naked man tried to kick in the door of the Fort Lauderdale Police Department in Florida because he thought a mob was trying to kill him. Another, experiencing similar hallucinations, tried to climb the police station fence and became impaled on a spike, police said. He was taken to hospital and survived.

Other cases included a man who ran naked through a neighbourhood convinced he was the Norse god Thor, and tried to have sex with a tree.

Last week, Qushanna Doby, 20, was charged with child neglect after her 1-year-old baby was found abandoned in the street. She said she had blacked out after taking the drug and couldn’t remember where she left the child.

Flakka is mostly made in China and Pakistan and smuggled to the US through the post. It is usually sold in crystal form and can be smoked, injected or swallowed.

Don Maines, a drug treatment expert in Fort Lauderdale, said: “They feel stronger and more sensitive to touch. But then the paranoia sets in. It seems to be universal that they think someone is chasing them. It’s just a dangerous, dangerous drug.”