How some prisoners will do anything to get hold of Spice - known as 'green crack'

"It's called green crack, once you have taken it once, you're on it."

That is Dave's experience of the so-called legal high Spice, which he became addicted to after taking in prison.

And figures given to Newsbeat suggest Dave is far from alone.

The government says it takes "a zero tolerance approach to drugs in prison" but Spice was pretty easy to find, Dave says.

"The minute I picked up that legal high I couldn't put it down," he explains.

"I was a crack head for many years and found it easier to get off crack cocaine than this.

"I was using it to block out my feelings and emotions because I didn't want to show other prisoners how I was feeling."

Dave went to prison for robbery and selling Class A drugs and he says he lost touch with his family and two children.

He admits that he used Spice to block out the pain.

"I became more paranoid through smoking it... peeping out of the cracks of my cell door and [I] couldn't be around people.

"I always felt like I was having heart attacks. I was in a bad place."

While in prison he worked as a cleaner and says he would often clean up the mess following an inmate's bad reaction to Spice.

He describes "people going over on it" and "people having seizures" and "a lot of people in pain".

And he told us about a particularly frightening experience.

"Someone ran into a wall head first because he was so paranoid. He thought that's where his cell was. He cut his head open and his bowels went."

Dave has mental health problems and thinks using Spice has made things worse.

He says he's more paranoid than ever before and will require medication for the rest of his life.

But he's hopeful that since getting treatment for his addiction his life will continue to improve.

"I've got people I love back in my life. I can be a son, I can be a father."

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