Ketamine can cause very serious bladder problems, with the urgent and frequen need to pee. This can be very painful and often pee can be blood-stained and can contain tissue from the wall of the bladder. Although stopping using ketamine can help, sometimes the damage can be so serious that the bladder needs to be removed by surgery. The urinary tract, from the kidneys down to the bladder, can also be badly affected and incontinence (uncontrolled peeing) may also develop.