As a study shows an increase in the use of "speedballing", the practice of taking heroin and cocaine together, one user described what impact this addiction has had on his life.
More drug users are taking heroin and cocaine together
Dave, 23, moved to Manchester a year ago and has been living rough in the city centre.
He was already on heroin, but swiftly moved onto speedballing after moving to the city.
"Drug dealers here sell heroin and crack together as a package deal.
"Everyone else was doing it, so I didn't even think about it and have been speedballing for a year.
"You get more of a rush compared to other drugs and it is very addictive."
It got to the stage, where Dave was spending most of his money on his habit.
"As I've been living on the streets, I've been getting money through begging.
"On weekends, I can get £150 and it reached a point where I could easily spend almost all of it on speedballing."
"You stop paying attention to your body.
"Sometimes I go through several days without eating, because the drugs are so addictive you don't feel like eating and it takes its toll on your body."
Dave finally decided to seek help after his girlfriend convinced him to go on the heroin substitute methadone.
He also sought help from the Manchester drugs charity Lifeline, who have provided him with counselling and clean needles.
He advises would-be drug users to speak to current addicts to get a reality check.
"If you talk to someone who's been doing speedballing for a long time, you'll see how it's affected them.
"They've probably wasted away into a walking skeleton and are dying inside.
"When I was in prison I used to do drug workshops at schools, describing how my life fell apart before my eyes because of drugs.
"I hope the message gets through."