Tough new NSW laws banning a range of synthetic drugs come into effect on Monday, the state government says.

In a statement, the government said the new legislation made it an offence to possess, manufacture, supply or advertise "psychoactive substances".

It said penalties for breaching the laws included a $2200 fine or two years imprisonment.

"There is no silver bullet to protect people from the scourge of these psychoactive substances, but the NSW government now has groundbreaking laws in place which will continue to make a significant impact," Fair Trading Minister Anthony Roberts said.

The new laws also make it an offence to possess, supply, or manufacture substances listed in Schedule 9 of the Commonwealth Poisons Standard, the O'Farrell government says.

Under the laws, it's also an offence to manufacture, supply or advertise any psychoactive substance for sale for human consumption.

The changes come after 45 new substances, which consist mainly of synthetic substances, were deemed prohibited drugs in September.

Minister for Mental Health, Kevin Humphries, said synthetic drugs were "a real danger to people's safety".

"These products can contain untested chemicals, with unknown toxicity," he said.

"(Users) are playing Russian roulette with their health."