Toronto police say more people are getting behind the wheel while on drugs this year compared to last year.

They say 25 drivers have been charged with impaired driving due to drug use so far this year, up from 10 at this time last year. That's an increase of 150 per cent.

"Surprisingly, it's not necessarily marijuana that's causing the rise," said Const. Clint Stibbe. "It's actually what they call a poly drug where there's more than one drug in an individual's system."

Stibbe says Toronto police are still charging people for driving impaired by marijuana but officers are seeing the "biggest growth" from cases where drugs have been combined, such as narcotics and depressants.

Meanwhile, the number of alcohol-related charges has dropped by roughly seven per cent — 431 as of last week, compared to 464 to the same time last year.

A major difference between dealing with alcohol-related and drug-related impaired driving cases is that there's no approved roadside device to test for drugs, says Stibbe.

driving stoned

Drivers impaired by drugs face criminal charges but do not currently have their licence automatically suspended. (Shutterstock)

Right now, the only way drug impairment can be checked roadside is through a drug recognition officer.

"They can do a sobriety test at the roadside and they can actually make those assessments there," said Stibbe.

"But if it's just an officer who maybe doesn't have that training then it is a situation where you would be placed under arrest for impaired operation and then dealt with accordingly based on the test you're subjected to when you get back to the station."

Drivers impaired by drugs face criminal charges but do not currently have their licence automatically suspended like those who fail a breathalyzer test.

That is set to change this fall after legislative amendments take effect.

"Going forward we have to accept that drugs are becoming more common place in society and as a result our enforcement has to be more focused," said Stibbe.

"Drugs remain in your system for a very long time and the impairment starts at a very low amount."

With files from The Canadian Press