8 Ketamine Side Effects to Know About When Using It for Depression

Ketamine (Ketalar) is an injectable medication that’s FDA approved for surgical anesthesia. But at lower doses, ketamine is used off-label for depression. And it’s becoming a more popular choice in light of emerging evidence that it can rapidly improve depression symptoms. 

But like any medication — especially one used for anesthesia — ketamine comes with some serious side effects. So if you’re considering this treatment, it’s important to learn about the safety risks.

A quick note before we dive in. In this article, we focus on the intravenous (IV) form of ketamine. But there’s a nasal spray form — esketamine (Spravato) — that’s FDA approved for people living with treatment-resistant depression or depression with suicidal thoughts. Another GoodRx article covers Spravato side effects in depth.

Ketamine side effects at a glance

We go through the side effects and safety risks in greater detail in the sections below. But if you’re looking for a quick list, the most common ketamine side effects include:

• Dissociation (feeling disconnected from your thoughts and surroundings)

• Drowsiness

• Dizziness

• Disorientation

• Nausea and vomiting

• Temporary increased anxiety

• Mild increase in blood pressure and heart rate

These side effects usually go away in the first few hours after treatment. But ketamine’s antidepressant effects typically last much longer. People often experience continued relief from their depression for several weeks after treatment. 

Serious ketamine side effects are less likely with doses used for depression. They’re more likely with higher doses of ketamine used for anesthesia — or when ketamine is misused. Rare but serious side effects may include:

• Hallucinations (seeing or hearing things that aren’t there)

• Dangerously high blood pressure 

• Increased strain on the heart

• Slowed breathing

• Dependence 

Below, we’ll look at eight notable ketamine side effects in greater detail.

1. Dissociation

At higher doses, ketamine is used as an anesthetic for anything from small procedures to major surgeries. This means it causes sedation or complete loss of consciousness. 

Dissociation can occur with the lower doses of ketamine used for depression. This is a trance-like state of feeling disconnected from your body or the world around you.

You might start feeling strange or woozy as ketamine enters your system. Hallucinations, numbness, and temporarily losing the ability to speak are also possible. This is part of the reason a healthcare professional will monitor you for a few hours after you receive ketamine. By the time you leave, you should no longer be feeling any dissociative effects.

Arrange for someone to drive you home after your ketamine treatment. Having a support person stay with you at home is a good idea, too. If you have any unusual experiences or still feel strange the next day, let your care team know.

2. Drowsiness

Drowsiness is one the most common side effects of ketamine. So it’s a good idea to take it easy for the rest of the day after your ketamine treatment. This includes avoiding activities that require alertness, like driving or caring for a small child.

If you take other medications that cause drowsiness, excessive sleepiness may be more likely. Be sure to provide your healthcare team a complete list of all the medications you take before receiving ketamine. This will help them check for ketamine interactions that may worsen drowsiness or other side effects.

3. Dizziness

Many people report dizziness after receiving ketamine. Dizziness is usually temporary, but be careful to avoid falls and injuries. Some tips include:

• Make sure your walkways at home are cleared of tripping hazards. 

• Consider having someone stay with you the day you have treatment. They can help you get around and make sure you feel steady on your feet. 

• Take your time changing positions (like standing up) or changing direction (like turning around while walking). These movements can provoke dizzy spells.

• Stay well hydrated. Dehydration can contribute to dizziness.

If you’re feeling dizzy when it’s time to head home after your appointment, let someone at the clinic know this. They may want to monitor you a bit longer before you go home.

4. Nausea and vomiting

Nausea is also one of the most commonly reported side effects of ketamine. Your healthcare team may recommend you avoid eating or drinking in the hours before your treatment to help prevent nausea and vomiting. They may also prescribe a medication to help, such as ondansetron (Zofran). Or they may even suggest you take the medication in advance of your ketamine dose if you’re prone to feeling queasy.

5. Increased blood pressure

Ketamine can raise your blood pressure. Changes in blood pressure are usually minor, but they’re more likely with higher doses. And larger increases in blood pressure might be more likely if you have uncontrolled high blood pressure already. This is why it’s important to receive ketamine treatment with close medical supervision and monitoring.

A healthcare professional will check your vital signs before, during, and after your ketamine treatment. If your blood pressure is too high before you receive the medication, they may delay treatment or give you medication to bring it down. Up to 20% of people receiving IV ketamine for depression may require blood pressure medication during their infusion.

If you have any pre-existing heart conditions, your healthcare team should talk with you about the specific safety risks involved. In addition to increases in blood pressure, other heart problems — like abnormal heart rhythm — are also possible with IV ketamine. It’s very important to inform your care team if you experience chest pain, trouble breathing, or intense dizziness at any point before or after treatment.

6. Slowed breathing

Ketamine can slow your breathing — but this is rare. It’s more likely that breathing slows down when ketamine is used for sedation or when it’s combined with other sedating medications. Examples include:

• Benzodiazepines like alprazolam (Xanax)

• Opioids like hydrocodone

• Muscle relaxers like cyclobenzaprine

• Barbiturates like phenobarbital

• Alcohol

Your care team may recommend avoiding certain medications before you receive ketamine. And they’ll also monitor your vital signs to make sure you’re breathing normally before you go home.

7. Suicidal thoughts and behaviors

Ketamine might help reduce suicidal thoughts related to your depression. But ketamine treatments don’t work for everyone. And it’s possible to develop new thoughts of self-harm after starting treatment.

If you or a loved one develop warning signs of suicidal ideation during or after ketamine treatment, get medical care right away.

Good to know: If your loved one is experiencing suicidal thoughts, find tips on how to talk to them about it in this video.

If you or someone you know is having thoughts of suicide, you’re not alone, and help is available. Call the National Suicide Prevention Lifeline at 988, or text HOME to 741-741 to reach the Crisis Text Line.

8. Misuse

Ketamine is a controlled substance because it has a risk of dependence and misuse. These risks are less likely when ketamine is given in a medical setting for depression because the doses are controlled, monitored, and spaced an appropriate amount of time apart.

Even though misuse is a risk, this is still unlikely in most people who are considering ketamine treatment. In other words, a single treatment doesn’t lead to addiction. People with a past or present substance use disorder may be at greater risk for potential misuse. 

The FDA also warns against home use of ketamine pills or nasal sprays made by compounding pharmacies. Unregulated forms of ketamine can put you at increased risk of overdose and more serious side effects if you use it on your own at home. Potential risks and side effects also change with repeated ketamine misuse. For example, this can lead to liver injury or a serious condition called interstitial cystitis — bladder inflammation that may lead to kidney damage.

If you or someone you know struggles with substance use, help is available. Call SAMHSA’s National Helpline at 1-800-662-4357 to learn about resources in your area.

Frequently asked questions

Why trust our experts?

Written by:

Daphne Berryhill, RPh

Daphne Berryhill, RPh, has two decades of experience as a clinical pharmacist. She spent most of her career in the Chicago area practicing in-home infusion.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Our editorial standards

Meet our experts