Dangerous ‘legal highs’ are replacing cocaine and cannabis as the drugs to abuse among some young people, police believe.

Police attended nearly three times as many incidents involving the chemicals last year compared to the year before, new research shows.

Officers believe one possible reason for the rise is changing habits among youngsters, as well as the increased availability and range of the drugs, sold both online and on the high street.

A Sussex Police spokesman said: “Some younger people are using these products instead of illegal controlled drugs such as cocaine, cannabis and amphetamine, because they are told that they are legal and therefore make the assumption that they are safe and cheaper. That is an unwise assumption.”

Although known as legal highs, the drugs are typically not authorised for human consumption and are often sold as room freshener or plant food to get around the law.

Sussex Police recorded 75 incidents involving the drugs in 2014, compared to 24 in 2013 and just four in 2011.

Most call-outs were reported as ‘medical’ or ‘suspicious behaviour’, while some involved domestic abuse or antisocial behaviour, according to the figures from the Centre for Social Justice. Sussex Police said it was working with hospitals, neighbouring forces and other partners to try and get a handle on the problem and identify cases where prosecution might be necessary.

A spokesman added: “However, this is a national issue which needs structured and sensible approach by police and their partner agencies to protect users, and prosecute suppliers wherever there is evidence of criminal activity.”

A West Sussex County Council spokesperson highlighted the danger of the drugs, noting: “The term ‘legal high’ is misleading as it implies that they are safe or approved for people to use, when in reality it means that they’ve not been declared illegal.

“Non prescription substances vary hugely and can carry serious health risks.

“The chemicals that they contain have, in most cases, never been used in drugs for human consumption before. This means they haven’t been tested to show that they are safe.”

A Brighton and Hove City Council spokesman said the issues were “by no means straightforward” but there were a “range of powers” available to help tackle the problem depending on the circumstances, such as closure orders and civil or criminal proceedings.

University of Sussex medical student Hester Stewart died after taking the unclassified party drug GBL in 2009.

Since then her mother Maryon has set up the Angelus Foundation charity.

Last October she wrote a letter to David Cameron pleading with him to publish a report into the dangers of legal highs.

The figures

Researchers from the Centre for Social Justice asked the question: For each of the last four years for which figures are available, how many incidents have been recorded where the term ‘legal high’ has been logged? Sussex Police said there were 75 in 2014, 24 in 2013, 12 in 2012 and four in 2011.

Of the 2014 incidents, 25 were reported as a medical/concern incident, and 22 as suspicious. One was initially described in the category of violent crime.

As a comparison, Lancashire police recorded 347 incidents and Lincolnshire police 820.

Sussex Police could not comment on the comparison as forces record incidents differently.