Powdered ketamine is often cut with other drugs, so it’s very hard to tell what the long-term effects will be—interactions can be very unpredictable.
Consequently, the long-term effects are varied, but they fall into several main areas.
As with any anesthetic, ketamine reduces—or even eliminates—pain. It’s hard for users to tell whether they’ve injured themselves, so they can end up hurting themselves severely.
Some people have suffered from broken legs and effectively crippled themselves because they couldn’t tell that something wasn’t right. Walking on a broken leg can result in compound fractures, penetration of the skin, sepsis, and serious nerve damage.
Once the effects of ketamine have worn off, users might experience severe abdominal pain.
It can also cause a thickening of the bladder and urinary tract, and this can force some long-term addicts to have their bladders removed as the walls are too thick and prevent urine from passing through. Other issues include kidney problems, which are caused by the drug’s interaction with the kidneys as it is reduced into its metabolites.
Amphetamines should never be mixed with ketamine because they can cause very high blood pressure.