Ketamine can be swallowed, snorted or injected. It’s also sometimes smoked with cannabis or tobacco. The effects of ketamine may be experienced within one minute if injected, 5–15 minutes if snorted, and up to 30 minutes if swallowed. Its effects can last for around an hour, however an individual’s coordination or senses may be affected for up to 24 hours after initial use.4

Effects of ketamine

Use of any drug can have risks. It’s important to be careful when taking any type of drug.

Ketamine affects everyone differently, based on:

  • size, weight and health
  • whether the person is used to taking it
  • whether other drugs are taken around the same time
  • the amount taken
  • the strength of the drug (varies from batch to batch)

The following effects may be experienced:

  • feeling happy and relaxed
  • feeling detached from your body
  • lowered sensitivity to pain
  • visual and auditory hallucinations
  • confusion and clumsiness
  • increased heart rate and blood pressure
  • drowsiness
  • slurred speech and blurred vision
  • anxiety and panic
  • vomiting
  • Going into a k-hole (intense detachment from reality, usually only happens at high doses).3,4,6
How long do drugs stay in your system?

Overdose

If you take a large amount of ketamine or have a strong batch, you could overdose.

The risk of death from ketamine alone is low, due to its ability to cause unconsciousness with minimal impact on airway reflexes or blood circulation.6 However, individuals are at a higher risk of physical harm/accidents while under the influence of the ketamine.6

Call an ambulance straight away by dialling triple zero (000) if you, or someone else, has any of the following symptoms (Emergency services are there to help and can provide instructions over the phone):

  • difficulty breathing
  • blurred vision
  • high blood pressure, fast heartbeat
  • convulsions/seizures
  • delirium or psychosis
  • unconsciousness.3,4,6

Coming down

The day after using ketamine, you may experience:

  • memory loss
  • impaired judgement, disorientation
  • irritability and restlessness
  • clumsiness
  • aches and pains
  • anxiety.1,3,7

Long-term effects

Regular use of ketamine may eventually cause:

  • flashbacks
  • poor sense of smell (from snorting)
  • mood and personality changes, depression
  • poor memory, thinking and concentration
  • abnormal liver or kidney function
  • ketamine bladder syndrome (see below)
  • abdominal pain
  • needing to use more to get the same effect
  • dependence on ketamine
  • financial, work and social problems.3,6

Ketamine bladder syndrome

Large, repeated doses of ketamine may eventually cause ‘ketamine bladder syndrome’ – a painful condition needing ongoing treatment.

Symptoms include difficulty holding in urine, incontinence, which can cause ulceration in the bladder.

Anyone suffering from ketamine bladder syndrome should speak to a health professional immediately.3

Ketamine and mental health

Clinical trials and studies have assessed ketamine as a treatment for depression and shown good results.7

Currently esketamine hydrochloride a form of ketamine, is available as a nasal spray for the management of treatment-resistant depression in Australia.

On 1 May 2025, this prescription nasal spray, branded as Spravato®, was made available on the Pharmaceutical Benefits Scheme (PBS) for adults with treatment-resistant depression.8 This listing means the federal government subsidises the cost of Spravato®, making the medication more affordable.

Daily users of ketamine can experience psychotic-related symptoms, especially among people who have a history of mental illness.4

Tolerance and dependence

People who regularly use ketamine can become dependent on the drug. They may feel they need ketamine to go about their normal activities like working, studying and socialising, or just to get through the day. They may also develop a tolerance to it, which means they need to take larger amounts of ketamine to get the same effect.3

Mixing ketamine with other drugs

Mixing ketamine with other drugs can have unpredictable effects and increase the risk of harm.

  • Ketamine and alcohol: nausea and vomiting at lower doses. Can lead to more serious effects at higher doses such as passing out and vomit aspiration.
  • Ketamine and benzos/opioids/GHB: nausea, vomiting, vomit aspiration, difficulty breathing, passing out, and possible death.
  • Ketamine and ice/speed/cocaine: increase in blood pressure.8

Use of more than one drug or type of drug consumed at the same time is called polydrug use.4