Ketamine Side Effects: A Comprehensive Guide
Ketamine is a uniquely powerful compound with a complex and evolving story in medicine and wellness. To understand its side effects is to appreciate its dual nature: it is a valuable therapeutic tool and a substance with significant risks when used improperly. This evidence-based guide offers a compassionate exploration of ketamine’s side effects, empowering you to navigate your wellness journey with clarity and confidence.
How Ketamine Works as a Therapeutic Tool
Ketamine was originally created as an anesthetic, but it’s become one of the more intriguing tools in modern psychiatry. At lower doses, it targets the brain’s glutamate system, specifically the NMDA receptors involved in learning and neural plasticity. By briefly interrupting those pathways, ketamine encourages the brain to form new connections. This plasticity is believed to underlie its fast-acting antidepressant effects – sometimes within hours.
The psychological experience also matters. The dissociative state that ketamine creates – feeling removed from your body or transported into a more introspective space – can give people enough distance to examine thoughts or emotions that usually feel overwhelming. In a clinical environment, that shift becomes a therapeutic opportunity. Clinicians prepare patients beforehand and guide them afterward, helping make the experience meaningful rather than disorienting.
Common Short-Term Side Effects During and After a Session
When administered clinically, ketamine’s short-term side effects are mostly predictable. They show up during or immediately after a session, peak quickly, and fade within a few hours. Most people walk out feeling a little spacey and slowed down, and then they’re back to baseline by the next day
Psychological Effects
The psychological effects – dissociation, distorted time, dreamlike visuals – are common during a ketamine experience. People often describe feeling detached from their body or surroundings, as if they stepped sideways out of themselves. It can be surreal, introspective, or quietly profound, depending on the person and the dose.
In a clinic, facilitators should help you stay oriented, comfortable, and calm as the experience unfolds. For many people, that temporary shift in perspective becomes the most meaningful part of the session, offering clarity or emotional release once the medicine wears off.
Physical Effects
On the physical side, ketamine is usually uneventful. Mild nausea, dizziness, or a bump in blood pressure or heart rate can happen, but clinicians monitor these changes in real time.
Most physical symptoms resolve quickly after the session ends. You might feel heavy-limbed, tired, or slightly drained for the rest of the day, but the sensations taper as your system clears the drug. By the next morning, most people feel completely normal – sometimes even clearer than usual.
Cognitive Effects
During an infusion, your thinking may slow down. Concentration gets fuzzy and your short-term memory can feel unreliable, like your brain briefly switched to airplane mode. This is expected and entirely temporary.
As ketamine metabolizes, your cognitive function snaps back, typically within a few hours. By the time you’ve slept on it, the mental fog is gone, and many people report a better mood and perspective in the days that follow.
Potential Long-Term Risks and Serious Side Effects
Used occasionally and under medical supervision, ketamine has a strong safety record. But like most drugs with powerful neurological effects, the risks shift dramatically when you move from structured clinical care to frequent, high-dose, recreational use. Recognizing that differences are key to understanding ketamine’s long-term risk profile.
Bladder Damage and Cognitive Impairment (With Chronic Abuse)
One serious complication tied to long-term ketamine misuse is something called ketamine-induced ulcerative cystitis – a painful, progressive condition that can inflame and even shrink the bladder. A 2022 review states that regular ketamine use can increase the risk of contracting it by three to four fold. At its worst, it can lead to incontinence or require surgical intervention. The key words there are “regular” and “use”.
If you’re using ketamine under the watchful eye of a licensed facilitator, and adhering to a treatment plan, you’re unlikely to experience KIC. And remember that you should be screened and briefed before starting treatment. If you have concerns, talk to your facilitator; they should be able to tell you what to watch out for – frequent urination, pain, or blood in the urine are a few signs – so you can catch issues before they escalate.
Remember that ketamine is a brain-altering drug, and chronic use has been found to cause long-term cognitive impairment, mood disorders, and psychotic and dissociative symptoms. There is some research that shows certain traits, like executive function and memory, can return after abstaining from ketamine for a set period; in the linked study, that period was 12 weeks.
Cardiovascular Considerations
Your heart rate and blood pressure can rise after taking ketamine. Typically, those effects are temporary, and they should be manageable under the supervision of a professional. That said, anyone with hypertension, heart disease, or other cardiovascular disorders should proceed with caution.
Any reputable clinic will insist on full medical histories and baseline vitals before approving treatment. Some patients may require additional monitoring; others may be advised not to proceed at all.
The Potential for Psychological Dependence
Ketamine isn’t considered physically addictive since it doesn’t produce withdrawal symptoms like opioids or alcohol do. But some people can become psychologically hooked on the feelings of dissociation or the emotional lift ketamine provides. And then they’re chasing that effect by taking more ketamine more often.
A person will still experience those same sensations at a clinic, but the sessions are spaced out, the doses are regulated, and patients partake in follow-up sessions. Providers also monitor for signs of misuse and adjust treatment plans if needed.
The Role of Individual Factors in Side Effects
Ketamine doesn’t land the same way for everyone. Your age, weight, medical history, psychiatric background, and even your personality or expectations can shape how the experience feels and how side effects present. Two people can receive the exact same dose and walk away with completely different takeaways: one might feel relaxed and introspective, while another might experience stronger dissociation or temporary discomfort.
Individuals with conditions like anxiety disorders, bipolar disorder, or past trauma may respond differently, sometimes requiring additional preparation or closer support during and after treatment. Medications matter, too; certain antidepressants, mood stabilizers, or blood-pressure drugs can influence how ketamine metabolizes in the body or how intensely side effects appear.
That’s why reputable clinics insist on comprehensive screening before treatment to deep dive into medical history, psychiatric history, current prescriptions, and goals for therapy. The more providers know, the more precisely they can tailor dosing, pacing, and support. In practice, this personalization is what keeps ketamine therapy not just effective, but safe.
Frequently Asked Questions
How long do the immediate side effects of a ketamine session last?
Most short-term effects – like dizziness, nausea, or dissociation – fade within one to two hours after a session. Some people feel mentally or physically “off” until the next morning, but nearly everyone returns to baseline within 24 hours.
Can ketamine cause permanent brain damage?
There’s no evidence that medically supervised, low-dose, intermittent ketamine causes lasting brain damage. The cognitive and structural risks documented in research come from chronic, high-dose recreational abuse, which is a very different use pattern than clinical treatment.
Are the side effects of esketamine (Spravato®) different from ketamine?
Esketamine is one-half of the ketamine molecule, so its side effects are similar: dissociation, dizziness, nausea, and temporary blood-pressure increases. Because it’s FDA-approved, it must be taken in certified clinics with monitoring before, during, and after each dose.
What is a “k-hole,” and is it dangerous?
A k-hole refers to a high-dose, recreational dissociative state where a person feels deeply detached from their body and surroundings. It can be frightening or disorienting but isn’t typically physically dangerous on its own. Clinical dosing is intentionally far lower, though guided dissociation can still occur in a supported therapeutic setting.
Is it safe to mix ketamine with other substances?
No. Combining ketamine with alcohol, benzodiazepines, opioids, or other depressants can severely slow breathing and consciousness and can be life-threatening. This is why clinics screen for substance use and review all medications beforehand.
How do I know if I’m having a serious side effect?
In a clinical setting, your team monitors your vitals, mental state, and overall response throughout the session. They’re trained to tell the difference between expected therapeutic effects and signs of trouble—and they can intervene quickly if needed. Communicating what you’re feeling is part of the process.
Sources
- Yip R, Swainson J, Khullar A, McIntyre RS, Skoblenick K. Intravenous ketamine for depression: A clinical discussion reconsidering best practices in acute hypertension management. Front Psychiatry. 2022;13:1017504. Published 2022 Sep 29. doi:10.3389/fpsyt.2022.1017504
- Anderson DJ, Zhou J, Cao D, et al. Ketamine-Induced Cystitis: A Comprehensive Review of the Urologic Effects of This Psychoactive Drug. Health Psychol Res. 2022;10(3):38247. Published 2022 Sep 15. doi:10.52965/001c.38247
- Strous, J. F. M., Weeland, C. J., van der Draai, F. A., Daams, J. G., Denys, D., Lok, A., Schoevers, R. A., & Figee, M. (2022). Brain Changes Associated With Long-Term Ketamine Abuse, A Systematic Review. Frontiers in Neuroanatomy, 16. https://doi.org/10.3389/fnana.2022.795231
- Tang, W. K., Lau, C. G., Ungvari, G. S., Lin, S.-K., & Lane, H.-Y. (2019). Recovery of cognitive functioning following abstinence from ketamine. Addictive Behaviors, 99, 106081–106081. https://doi.org/10.1016/j.addbeh.2019.106081
