The mother of a young Irish boy has pleaded with the government to introduce legislation to make cannabis treatment legal.

Yvonne Cahalane says she has had to move to America to get the treatment for her son Tristan (2), who suffers from Dravet syndrome.

The syndrome is known as a severe form of epilepsy.

"It's a complicated process, there isn't a medication that's out there, in the pharmaceutical industry at least, that can control it" she told Newstalk Breakfast.

"The seizures are long and they can end up to going up to 500 a day for some people".

She says her son was having up to 20 varying types of seizures a day, and that he was prone to a lot of injuries.

"We wanted to find something...out there that would work", she explains about what led them to the cannabis treatment.

"It's a cannabis oil - just the whole plant, so that you have the broad spectrum of all the compounds in the plant".

The product can come in drops, patches or a thick paste.

"It has done wonders, he's a new child...Within days there was a difference", Yvonne says.

She says their US visa is up in December, and is calling on the Irish government to help.

A petition for Tristan has also been set up by his mother.