Ketamine is both a hospital medicine and a street drug. In medical settings it is an anesthetic and a treatment for depression (see Article 13). Outside medicine it is used for its dissociative effects, which can feel like detachment from body and surroundings. This article covers what people should know about the risks.

What it does

Ketamine blocks NMDA receptors in the brain, producing dissociation: a sense of separation from your body and environment, altered perception, and reduced pain. Effects begin quickly and last a relatively short time compared with psychedelics, though the aftereffects can linger. At higher amounts, people can become unable to move or respond, a state often called a “K-hole,” which can be frightening.

Immediate risks

Accidents and injury. Dissociation reduces coordination, balance, and pain awareness. People fall, get hurt without noticing, or walk into traffic. Being in a safe place with someone sober nearby matters a great deal.

Vomiting while impaired. Nausea is common. If someone is unable to respond and vomits, they can choke. The recovery position (on their side) helps protect the airway.

Dangerous combinations. Ketamine combined with alcohol, opioids, benzodiazepines, or GHB increases the risk of breathing problems, loss of consciousness, and vomiting. Combinations are among the biggest avoidable risks.

Heart effects. Ketamine can raise heart rate and blood pressure.

Psychological effects. Some people experience confusion, anxiety, or panic during or after use. Rarely, symptoms such as paranoia can persist.

Vulnerability. Impaired people are at higher risk of theft, assault, and being taken advantage of. Use only with people you trust.

Long-term harms

Bladder and urinary problems. Regular use is associated with ketamine-related cystitis: pain, urgency, frequent urination, blood in urine, and in severe cases lasting bladder damage that can require surgery. These effects are well documented in frequent users. Early symptoms are a signal to stop and see a doctor, since damage may be partly reversible if caught early.

Abdominal pain. Some regular users develop severe stomach pain, sometimes nicknamed “K-cramps.”

Dependence. Ketamine can be psychologically addictive, with cravings and escalating use.

Cognitive effects. Heavy, long-term use is associated with memory problems.

Nasal damage. Snorting can irritate and damage nasal tissue.

Supply risks

Street ketamine is often not what it is sold as. Look-alike products and adulterants circulate. Drug checking, where available, can help. Because fentanyl contamination has been found in unregulated stimulants and pills, carrying naloxone is sensible for anyone who uses drugs socially. Reagent tests have limits (see the drug checking article).

Harm reduction principles

Without giving amounts or schedules, the main public-health messages are:

• Don’t use alone, and ensure at least one sober person is present who can help if something goes wrong.
• Stay in a safe, familiar place, away from water, stairs, roads, and heights.
• Avoid mixing with alcohol or other depressants.
• Avoid frequent use; give your body long breaks, since risk of bladder harm rises with frequency and amount.
• Don’t drive, and don’t take part in any activity that requires coordination until fully recovered.
• Watch for bladder symptoms and get medical advice early.
• Know the signs of an emergency: unresponsive, blue lips, very slow or irregular breathing, or repeated vomiting. Call emergency services.

Medical ketamine versus street ketamine

The clinical use of ketamine for depression is not the same as recreational use. Medical doses are controlled, patients are screened and monitored, and the product is pharmaceutical-grade. Clinical benefit does not imply that unsupervised use is safe or therapeutic.

Getting help

If you’re using more than you want to, having bladder pain, or finding it hard to stop, a family doctor or addiction service can help. You don’t need to have hit bottom to ask.

The takeaway

Ketamine’s biggest risks are accidents, dangerous combinations, and, with repeated use, bladder damage. Planning ahead and looking out for each other lowers risk, and early symptoms of bladder trouble should never be ignored.

Sources: General pharmacology and public-health harm-reduction guidance. Confirm specifics at DanceSafe, TripSit, or PsychonautWiki.