Police in the US are investigating after 33 people were treated in hospital after suffering a bad reaction to a batch of drugs.

Large numbers of people were spotted collapsing and being sick in the middle of a street in New York. In total, 33 of them were taken to hospital on Tuesday, suffering from a suspected overdose of K2 – a type of synthetic cannabis made from man-made chemicals.

The incident happened at around 9.30am in Brooklyn’s Bedford-Stuyvesant neighbourhood, an area known for being popular with drug addicts who use K2.

Eye-witnesses reported seeing people lying unconscious in the street and falling to the ground.

According to the New York Post, the police went to an area outside a community garden after receiving reports of a group of people with an altered mental state. All of the people involved are expected to recover with medical treatment.

Synthetic drugs can have a strong effect on users

Research has found that synthetic cannabis can have a stronger effect than the natural drug. And users often don’t know what the drug they are taking actually contains so it is hard for them to predict how their body will react to the substance.

K2, which is also known as Spice, Dank, Smacked and AK-47, has become popular in New York with two people dying as a result of taking it. Since 2015, more than 6,000 people in the city have sent to hospital after feeling unwell from taking K2.

In fact, the substance has become such a problem the Mayor of New York, Bill de Blasio, made it illegal in October last year. Now anyone who produces or sells K2 in New York City can be jailed for up to a year or fined more than $100,000.

New synthetic versions of illegal substances can be challenging to detect using drug testing. Tests can identify whether someone has taken a particular drug within a certain timescale but usually focus on well-known substances like cannabis, heroin, cocaine, MDMA, ketamine and amphetamine.

But testing could be developed to pick up some of the ingredients found in this new breed of chemical drugs. And using a drugs test can be a good starting point if you are concerned someone you love may be abusing drugs or you have noticed a sudden change in behaviour.