Ketamine: 'I thought my bladder was going to explode'
K bladder, caused by the drug ketamine, is a bigger problem in the UK than anywhere else in Europe, according to the country's leading expert.
David Gillatt, chief urologist at Bristol University, says the condition has forced him to remove the bladders of young people.
Two former users, Matt and Jamie, have been telling Newsbeat about their use of ketamine.
Warning: You may find some of the details in their stories distressing.
Matt, 28, from Bristol
"I started taking ketamine in clubs and parties in Bristol but things started to spiral out of control after nearly going to jail.
"I was just using it to cope with life really, just using more and more until my body couldn't hack it and I started getting really ill.
"It started creeping into every aspect of my life and that becoming the main part of my life. I started selling drugs to support that.
"Everyone around me started getting stomach cramps and getting really ill and peeing blood.
"All the other drugs pretty much went out of the window.
"I hated being me. I think I was trying to kill myself without actually giving up.
"At my worst I was taking 15g a day. I was buying in bulk thinking I'd ration it out but I was doing it all in one night.
"Eventually using all the time because it was taking away the pain that I was in physically, but it was causing all the pain as well making my body deteriorate.
"It was the only thing that would stop how much pain I was in but it was what was causing it. I was stuck in a cycle.
"I've woken up on the bathroom floor with blood everywhere fitting out on the floor, where I have been in so much pain. I eventually got into heroin because it was the only thing that got anywhere near to easing the pain that ketamine caused.
"I had a catheter fitted. It was a tube going in through my stomach into my bladder because my bladder had just shut down basically.
"My bladder collapsed around the catheter. I was still taking ketamine because I was in a massive amount of physical pain.
"I had numerous suicide attempts because I couldn't cope with how much pain I was in. I was actually peeing out chunks of my bladder.
"The bladder wall was falling apart. There was so much scar tissue. I was permanently curled up in a ball unable to stop sweating just in absolute agony.
"I'm four months clean now of all drugs but I am still awaiting another operation to check to see how bad my bladder is.
"Eventually I might have to have my bladder removed and half my bowel removed to make a new bladder. I'm scared about the side effects of the operation, not being able to have kids, the prospect of it not working.
"It's an evil drug which is just corrosive on your body it just strips you down in a matter of years. It was uncontrollable."
Jamie, 29, from Wakefield
"When I was really bad on it, basically spending £600 a week on it my bladder was absolutely destroyed.
"I was going to the toilet numerous times every hour. At one point I couldn't actually pee because my blood was clotted.
"It was the worst pain I have ever had. I never want to feel that again. I thought I was going to lose my bladder."
"It started as a weekend thing and then it soon deteriorated into Friday, Saturday, Sunday, Monday and it just went on and on to a point where it was daily.
"There was a point where I was having one hour of sleep a night - 23 hours a day on ketamine.
"I lost five or six stone in weight, down to eight and a half stone.
"I got really bad stomach cramps. It's like a really sharp pain in your stomach, it does not go away. It lasts for about three to four days and you're pretty much bed ridden. You can't walk apart from walking like a hunch back.
"The first time I peed blood, I was trying to pee and a tiny bit came out and then all of a sudden I could see this large thing come through me and it was a blood clot and five or six just flew out.
"I got in the bath and to see if I could pee in the bath to relieve the pain with warm water and then I couldn't go at all.
"I went to the hospital. I spent four nights in hospital. They had to stick some water into my bladder, put me on a catheter and flushed my system out.
"At that point I was still taking ketamine in hospital. Looking back I can't believe how daft I was.
"I probably estimate I spent £80,000 on ketamine over my addiction. I am currently £41,000 in debt.
"It's hindering me a lot more than I expected. I have got to pay back what I owe. Pay back my debt to society too."
Jamie's mum Sue told Newsbeat: "I know now that I have got my son back, because I used to say 'You're not my son when you take ketamine'.
"It's nice to have him back."
If you need help with any of the issues raised in this article you can get help from Talk to Frank.