Ketamine: a promising alternative for treatment-resistant depression

Written by: Dr Vimal Sivasanker
Edited by: Emma McLeod

When conventional treatments for depression aren’t successful, ketamine is a potential alternative. Is it right for you? Dr Vimal Sivasanker is a leading psychiatrist in London and Elstree who provides this treatment for his patients. After reading his comprehensive and easy to follow explanation, you’ll understand all the key aspects of taking ketamine for depression.

A woman looking into the distance with a forlorn expression,

What is ketamine?

Ketamine is an anaesthetic drug which was developed in the 1960s and, about 20 years ago, it was recognised as having an effect on depression. Recent studies have confirmed that ketamine has a very strong and quick-onset effect for treatment-resistant depression. Depression is classed as treatment-resistant when two other antidepressant medications haven’t worked.


Ketamine isn’t licensed for depression or pain and is only licensed as an anaesthetic. So, while it’s off-label, there is certainly evidence to support prescribing it for depression. I prescribe ketamine in my practice for several patients who have treatment-resistant depression.


How does ketamine manage depression?

Ketamine is different from other antidepressants. Most others work on a group of chemicals called monoamines (which includes serotonin and noradrenaline) and these work by increasing the amount of those chemicals in the brain. Ketamine, however, works differently. It works on a different chemical called glutamate and also increases the connections between different nerve cells in the brain. Furthermore, it can be used alongside conventional antidepressants if necessary.


How is ketamine taken?

Ketamine can be taken in a number of ways, but the route I use to treat depression in through a vein. Unlike when ketamine is given as an anaesthetic, this does not involve giving a large dose in one go to send you to sleep. Ketamine is slowly passed through the vein over about 40 minutes when treating depression, under the supervision of an anaesthetist, so the patient does not go to sleep. This is known as a ketamine infusion.


Does taking ketamine pose risks?

Like all treatments, ketamine has side effects. A common one that people describe is something called dissociation (feeling out of their own body). This varies in intensity, from mild and strange to severe and frightening (the latter is rare). There is some evidence that dissociation is a marker of how much ketamine has got into the brain and into the areas we want it to reach. Therefore, we look for some degree of dissociation to evaluate if the patient has had enough ketamine. This would be at a level which they can tolerate and it will indicate if the dose of ketamine is enough to affect the relevant part of the brain.


Other transient side effects are dizziness and change in blood pressure, but these are short-lived and usually end before the patient ends their treatment session. Bladder problems are very uncommon in prescribed ketamine treatment but may occur in people who abuse ketamine. This side effect is very rare in treatment because of the measures we take to evaluate the doses and monitor side effects.


Can patients become addicted to ketamine during treatment?

In the doses we prescribe for treatment-resistant depression, it is extremely unlikely that patients become addicted. At most in a medical setting, if a person takes too much over a long period of time, they might become tolerant, making it less effective, but consistent monitoring makes this uncommon.


How does a psychiatrist decide the frequency and dose?


The initial frequency of treatment is twice a week for three weeks. We do this to see if someone has a response to the treatment. Then, we re-evaluate to see if it has been successful.



A dose is initially decided on body weight. Then it will be reviewed and adjusted according to their response to the initial period of treatment.


How long do results last?

The effect of ketamine treatment is short-term in the initial period, about seven to ten days. This is why we initially provide it twice a week for three weeks. If the patient has a response to ketamine by the end of the three weeks, they might want to move on to maintenance treatment, which would be once every week or two weeks. We would then review their progress to see if the results can be maintained and potentially, treatment sessions even further spaced out. When we space out the sessions, patients receive ketamine less often and, as a result, the risk of becoming tolerant to it is decreased.


Are there alternatives to ketamine?

Because ketamine is used in treatment-resistant depression (meaning two other antidepressants have been tried and were not successful), patients will have tried other forms of treatment before ketamine is proposed. Ketamine is one of several potential treatments that are tried after antidepressants haven’t succeeded in managing depression. These include adding in lithium or antipsychotics, or other neuromodulation treatments like ECT (electroconvulsive therapy) or TMS (transcranial magnetic stimulation).


Each treatment has pros and cons and whether or not ketamine is the best alternative for you would be discussed in your assessment with your psychiatrist.


Visit Dr Sivasanker’s profile to discover how he can help you diagnose and manage depression.

By Dr Vimal Sivasanker

Dr Vimal Sivasanker is a leading consultant adult psychiatrist in London and Watford who specialises in a wide range of psychiatric disorders, including depression, anxiety and obsessive-compulsive disorder. He also treats complex psychological problems such as bipolar affective disorder (manic depression) and psychosis.

Dr Sivasanker completed his medical training at St Catharine’s College, Cambridge and at St Bartholomew’s and the Royal London School of Medicine. He completed psychiatric training on the East London, Cambridge and East Anglia rotations. Dr Sivasanker has worked extensively in inner-city and rural areas, treating a broad range of psychiatric disorders.

He holds an interest in neuromodulation for psychiatric disorders and is currently the Vice Chair of the Royal College of Psychiatrists’ Committee on electroconvulsive therapy (ECT) and related treatments. Dr Sivasanker has written and developed training competencies for the College as well as delivering training at a national and international level.

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