Ketamine is classed as a dissociative anaesthetic drug although its chemical structure ensures it is an adaptable medication that can provide a range of health-associated benefits for use by medical professionals.
Ketamine induces a physical state of sedation in patients enabling them to feel relaxed and calm, it also allows people in pain to detach themselves from their discomfort.
The effects of ketamine can be felt within minutes if injected, 10-20 minutes if snorted and 30 minutes if swallowed which is a short space of time for a drug administered orally to take effect.
Its effects tend to last for one hour, but this can fluctuate depending on the strength of the ketamine that has been consumed. (11)
As ketamine is a psychoactive drug its chemical properties attach to receptors in the brain and cause a range of effects which can change our mood, perception, cognition and behaviour.
Like all medications, the complex chemical content of the drug means that it contains several effects that may appeal to recreational drug users who are seeking to elevate their mood, experience distortions to their perception and escape from their everyday life.
The commonly desired effects of ketamine are:
The effects of ketamine ingestion include:
Ketamine’s chemical properties target several brain functions making it a very complex drug that will take time to be fully understood by scientists.
Ketamine can affect the opioid receptors in the brain which explains why it provides feelings of euphoria and can also assist with pain relief.
Ketamine also significantly affects the glutamate neurotransmitter in the brain which plays a prominent role in building and maintaining connections between neurons in the brain.
This ensures that all the neurons in the brain communicate efficiently with each other to keep brain activity flowing efficiently. (16)
Ketamine causes a different effect on the glutamate system depending on how much ketamine a person takes. At low doses, glutamate production is boosted to a high level meaning there is a surge in communication between neurons.
This explains why recreational users will experience effects such as pleasure, hallucinations and a sense of detachment.
At high doses, however, glutamate’s effects are blocked which means neural connections are diminished which could result in a user/patient becoming sedated as they experience strong hallucinations which may be unpleasant.
Consuming higher levels of ketamine will eventually lead to a state associated with general anaesthesia. (16)
Due to its chemical makeup ketamine provides a range of physical benefits that can be used for several medical purposes, including:
As a dissociative anaesthetic, the number one use for ketamine will be as an effective drug for sedating patients before they undergo operations or other medical procedures.
Ketamine tends to be used alone or in combination with other anaesthetics such as nitrous oxide and used in accident and emergency hospital departments over a short-term period, particularly to:
Ketamine has been established as a safe drug for children for sedation in accident and emergency department settings. (12)
Ketamine has high credibility as an analgesic medication and is therefore excellent for pain relief outside surgical operating theatres.
It produces similar pain-relieving effects to both morphine and fentanyl, but it has the added bonus of not having a depressive effect on the respiratory process, making it a safe drug to use.
Medical practitioners tend to use lower doses of ketamine to relieve severe pain, as low doses of ketamine are capable of treating pain and do not cause strong dissociative effects. (2)
Some common examples of the types of pain that ketamine helps with include:
Research from China in 2015 has found that ketamine can be effective in treating Refractory Status Epilepticus (RSE) which is a form of epilepsy that several other medical approaches to treating seizures have been unsuccessful in treating.
This was an important discovery as the usual anti-seizure drugs do not work on this condition which can lead to brain damage and death if not treated.
Luckily ketamine takes effect quickly and targets key brain areas with its anticonvulsant effects meaning healthy connections between nerve cells in the brain are maintained. (15)
Over recent years it has come to the attention of medical researchers that ketamine’s properties can alleviate symptoms of depression in patients who have not responded well to the usual, standard treatments for depression.
Ketamine has also been shown to reduce feelings of suicide in people who were previously contemplating the act. (6,7)
Research has provided evidence that ketamine does generate an antidepressant effect when it has been analysed during clinical trials examining the use of single intravenous infusions in people with depression.
Almost one-third of patients report an improvement in their condition three days after receiving the ketamine infusion, and just under 75% of patients reported feeling better for at least one day after receiving ketamine.
Over half of the people who took part in clinical trials stated that the benefits they received from ketamine were significantly positive enough to ensure they would carry on using it given the chance. (8)
Ersketamine is a drug which is chemically similar to ketamine and has shown similar positive effects in treating depression.
Research involving over 800 patients who consumed ketamine intranasally when combined with a new anti-depressant medication showed that over 40% of patients experienced a reduction in depressive symptoms.
Results of the study showed that many of their symptoms disappeared completely within 12 months of treatment. (8,16)
Clinical research trials have revealed that ketamine can also help treat postpartum depression, which is a common and potentially severe psychological disorder that can negatively impact the mother, child and the whole family.
Depression is seen as a frequent complication associated with childbirth with the condition affecting 10-15 % of mothers.
In a carefully designed experiment medical practitioners give one group of mothers a dose of ketamine as part of the anaesthesia process before giving birth, whereas another group were anaesthetised without ketamine before giving birth.
When assessing all the mothers for postpartum depression 6 weeks later it was found that the mothers who did not receive ketamine as part of their anaesthesia were more likely to be diagnosed with depression.
It was concluded that using ketamine as part of the anaesthesia process during pregnancy can help prevent postpartum depression.
However, these findings need to be confirmed in other research studies before it becomes established as a regular practice. (1)
Asthma has been described as an inflammatory disorder of the airways leading to chest tightness, coughing, wheezing and difficulty breathing which can be fatal.
Close analysis of ketamine’s effects also reveals that it can act as a bronchodilator and therefore ease the breathing process for patients with inflamed airways as a consequence of asthma.
Medical research carried out in India in 2013 revealed that when ketamine was used on patients with breathing difficulties (brought on by asthma) who had not responded well to other established treatments, their condition improved rapidly after receiving the drug.
There was also an improvement in the way their blood carried oxygen around the body to important organs. (3,5)
Several scientific studies analysing ketamine’s effects have found that it produces an anti-inflammatory effect meaning it can reduce inflammation and swelling in the human body after injury, trauma and infection.
Ketamine can therefore play a key role in maintaining homeostasis (physical balance) in our internal biology and ensuring tissues and organs can function efficiently. (9)
Research studies have reported evidence of ketamine’s significance in protecting brain cells, tissues and vital connections. This makes it a useful treatment option for people who have experienced head trauma and brain injury.
Ketamine has also been found to be effective for stabilising cardiovascular activity and therefore controlling the pressure in key arteries which carry blood to the brain to ensure it operates normally. (4,8)
A common physical consequence of becoming stressed or depressed is a loss of connections between brain neurons.
Ketamine has been shown to reverse the poor-quality neural connections that have developed in the brain over time which can slowly help to make the brain heal and carry out its usual functions.
Ketamine has several biological and chemical characteristics which explain why it can be applied to many different areas of medicine, such as:
Ketamine has the advantage of being a fast-acting drug when consumed when compared with other anti-depressant drugs and its positive, anti-depressive effects can take effect within a short period.
Ketamine is considered a safe drug to use medically and its clinical record pays testament to that. The risk of death from just taking ketamine alone is minimal, particularly when its use is overseen by medical experts, and there is no history of any complications associated with its use. (7,13)
Ketamine produces a mild stimulatory effect on the heart but does not suppress the respiratory process nor does it hinder the gag reflex which can cause a person to choke if it is not functioning effectively.
However, when ketamine needs to be used in higher doses there is a cause for concern as high doses of ketamine can lead to a higher toxic presence in the heart and respiratory system.
Ketamine is a drug that can be administered into the body via several routes because it is water and lipid soluble meaning it can pass easily through membranes in the body and take effect once ingested into the body.
Ketamine is therefore a drug that can be utilised as medication in several clinical scenarios. (4,8,11)
Ketamine can be consumed through the following routes:
As ketamine is a powerful, multi-use drug that is not yet fully understood by scientists it also has many disadvantages, including:
Ketamine’s chemicals can affect several brain processes, not just one, and many of these effects have not completely been established or fully investigated yet.
There is still so much to know in terms of ketamine’s long terms effects on several aspects of our physical and mental functioning.
Until ketamine is fully understood doctors will always be cautious about using the drug in some situations.
Like all medications and recreational drugs, ketamine causes a range of uncomfortable side effects that need to be endured which can affect people in different ways.
The main, common side effects that people experience when taking ketamine are likely to experience are:
There are other many other potential side effects apparent after ketamine use that patients can experience that fall into the following categories:
There are also several other drawbacks to ketamine as a medicine, including:
Despite its positive results in helping patients with depression improve their condition, ketamine has not yet been approved as a licensed treatment for depression.
This is because despite producing promising results, not enough research has been carried out in clinical trials to check that it is an efficient and safe drug to use over a long-term period. (4,7,8)
There may be some adverse and harmful consequences that have not been accounted for yet so there still remains a great deal of uncertainty about its use as a medication for depression.
Despite the promising results of ketamine infusion to treat depression, there are some patients that have experienced troublesome effects after going through the procedure.
Approximately one in ten people have reported finding the treatment challenging and some patients have reported a deterioration in their depressive symptoms whilst having the treatment with a small number of patients reporting suicidal thoughts.
On the whole, these symptoms pass in 15-30 minutes after the procedure although there have been a minority of patients who felt this way for two weeks after treatment.
In some cases, this is enough for them to stop receiving ketamine infusion altogether, although eventually after receiving one or two more ketamine infusions the negative side effects do subside for the majority of people receiving the treatment. (8,11)
Ketamine is a highly addictive drug so its use should be limited to a short-term period which is usually around 2-4 weeks if possible, if not then close medical supervision is essential.
Ketamine has a short half-life (1 -3 hours) and is a drug that takes effect quickly making it a high risk for physical dependence and addiction. A drug’s half-life refers to the period of time it takes for half the drug to leave the body.
Usually, the shorter the half-life of a drug the greater the risk for physical dependence as the body tends to develop a tolerance quickly to drugs with a short half-life. (14)
This means that anyone taking ketamine will gradually need to take higher doses to benefit from its physical effects.
After 2-3 weeks of increasing their dose strength ketamine users will find that they will experience withdrawal symptoms if they suddenly stop taking the drug.
This is a clear sign that they have developed a physical dependence on ketamine which can easily lead to ketamine addiction, a condition that would require medical treatment. (10,13)
(1) Alipoor, M. et al (2021) The effect of ketamine on preventing postpartum depression. Journal of Medicine and Life. 14(1). available@The effect of ketamine on preventing postpartum depression – PMC (nih.gov)
(2) Bell, R., Kalso, E. (2018) Ketamine for pain management. Pain reports. Sept-Oct 3(5) Available@ Ketamine for pain management – PMC (nih.gov)
(3) Farshadfar, K. et al (2021) The effects of nebulized ketamine and intravenous magnesium sulfate on corticosteroid resistant asthma exacerbation; a randomized clinical trial. Asthma Research and Practice 7. available@ The effects of nebulized ketamine and intravenous magnesium sulfate on corticosteroid resistant asthma exacerbation; a randomized clinical trial | Asthma Research and Practice | Full Text (biomedcentral.com)
(4) Gao, M. et al (2016) Ketamine use in current clinical practice. Acta Pharmacologica Sinica 37(7). available@Ketamine use in current clinical practice – PMC (nih.gov)
(5) Goyal, S. & Agrawal, A. (2013) Ketamine in status asthmaticus: A review. Indian Journal of Critical Care Medicine. 17(3) available@ Ketamine in status asthmaticus: A review – PMC (nih.gov)
(6) Harvard Health Medical School (2019) Ketamine for major depression: New tool, new questions. Available@ Ketamine for major depression: New tool, new questions – Harvard Health
(7) Harvard Health Medical School (2022) Ketamine for treatment-resistant depression: When and where is it safe? available@ Ketamine for treatment-resistant depression: When and where is it safe? – Harvard Health
(8) Kurdi, M., Theerth, K. & Deva, R. (2014) Ketamine: Current applications in anaesthesia, pain, and critical care. Anaesthesia Essays and Research. Sept – Dec 8 (3). Ketamine: Current applications in anesthesia, pain, and critical care – PMC (nih.gov)
(9) Loix, S. et al (2011) The anti-inflammatory effects of ketamine: State of the art. National Library of Medicine. available@ The anti-inflammatory effects of ketamine: state of the art – PubMed (nih.gov)
(10) Rassool, G.H. (2011) Understanding Addictive Behaviours. Palgrave MacMillan. New York.
(11) Rosenbaum, S. et al (2022) Ketamine. Ketamine – StatPearls – NCBI Bookshelf (nih.gov)
(12) Royal Children’s Hospital Melbourne. (2023) Ketamine use for procedural sedation. available@ Clinical Practice Guidelines : Ketamine use for procedural sedation (rch.org.au)
(13) Royal College of Psychiatrists (2017) Statement on Ketamine to treat depression. Available@ectcommittee-ketamine-to-treat-depression-statement-feb17.pdf (rcpsych.ac.uk)
(14) Wharrad, H. (2015) Pharmacology: Half-life of drugs. available@RLO: Pharmacology: Half-life of Drugs (nottingham.ac.uk)
(15) Yao Fang, Y. et al (2015) Ketamine for the treatment of refractory status epilepticus available@ Ketamine for the treatment of refractory status epilepticus – PubMed (nih.gov)
(16) Yin, H, (2021) What ketamine actually does to the brain. New Frontiers: Psychiatric and TMS.available@What ketamine actually does to the brain – New Frontiers Psychiatry & TMS | Milwaukee Psychiatrist
Boris is our editor-in-chief at Rehab 4 Addiction. Boris is an addiction expert with more than 20 years in the field. His expertise covers a broad of topics relating to addiction, rehab and recovery. Boris is an addiction therapist and assists in the alcohol detox and rehab process. Boris has been featured on a variety of websites, including the BBC, Verywell Mind and Healthline. You can connect with Boris online at LinkedIn or X.com.
