Short-Term and Long-Term Side Effects of Ketamine Treatment

July 3, 2026
Ketamine Therapy

Dr. Elyas Parsa, DO

What are the side effects of ketamine treatment? Explore common short-term effects, potential long-term risks, and how ketamine therapy is safely administered.

I’ve administered hundreds of ketamine treatments. And one of the first things I tell patients is this: you will feel something. That’s kind of the point.

But there’s a difference between expected effects and concerning side effects. There’s a difference between a temporary sensation and a lasting problem. And there’s a massive difference between what happens at therapeutic doses in a clinical setting versus what happens in uncontrolled environments.

If you’re researching ketamine side effects, you’re probably weighing whether this treatment is right for you. Maybe you’re dealing with treatment-resistant depression. Maybe chronic pain has stolen years of your life. Maybe you’ve tried everything else and you’re cautiously hopeful about ketamine but also appropriately skeptical.

Let me walk you through what the evidence actually shows, what I see in my Livermore clinic, and what you should genuinely expect.

Ketamine Infusion Side Effects: Does the Form Matter?

How ketamine enters your body changes what you feel and how intensely you feel it.

Intravenous (IV) infusions deliver ketamine directly into your bloodstream. This means faster onset (usually within a few minutes), more precise dosing control, and typically more predictable effects. It also means the dissociative experience tends to be more pronounced. Patients often describe floating, a sense of detachment from their body, or visual distortions. These are expected, not harmful. They’re part of how ketamine works on the brain’s default mode network.

Intramuscular (IM) injections have a slightly slower onset than IV but still act quickly (within 10 minutes). The experience is similar to IV, though some patients find it slightly less intense. The entire session also lasts up to an hour and a half, compared to 50 minutes for IV therapy.

Sublingual lozenges and nasal sprays (like Spravato, the FDA-approved esketamine) have lower bioavailability. This means more variable absorption, often a milder experience, and sometimes less reliable therapeutic effects.

In clinical practice, we prefer IM injections. While drip rate of an IV infusion can be adjusted if there are side effects, it’s typically not worth the hassle that comes along with it (IV in the patient’s arm, a beeping pump, potential annoying alarms from the pump – all things that distract from the experience).
Common side effects across all forms include:

Common side effects across all forms include:

Nausea (manageable with anti-nausea medication)
Dizziness or lightheadedness
Temporary increases in blood pressure and heart rate
Dissociation (feeling detached from your surroundings)
Blurred vision
Fatigue afterward

These typically resolve within one to two hours after the infusion ends. Whether you experience these side effects or not, you will need a ride home. You shouldn’t drive or make major decisions for the rest of the day. But by the next morning, most patients feel completely normal and free of side effects.

Short-Term Side Effects of Ketamine

Let’s separate “side effects” from “effects.” Effects are, quite simply, the expected effects of ketamine. This is what we expect to happen when ketamine is administered.

When ketamine works, it induces a temporary altered state of consciousness. Some people find this peaceful, even profound. Others find it unsettling the first time. Neither response is wrong.

During the infusion itself, patients commonly experience:

Dissociation: A sense of being separate from your body or watching yourself from outside. This is ketamine’s action on NMDA receptors, which temporarily quiets the brain’s usual patterns of rumination and self-criticism.
Perceptual changes: Colors may seem brighter. Sounds might feel distant. Some patients describe dreamlike imagery.
Emotional release: Occasionally, people cry during treatment. Or laugh. This isn’t a side effect so much as processing happening in real time.
Physical sensations: Heaviness in the limbs, warmth, or tingling.

After the infusion, for the next few hours:

Grogginess or mental fogginess
Mild headache (less common, usually responsive to hydration)
Fatigue
Nausea that fades within an hour or two.
- Clinically we also see that nausea is more associated with resistance to the medication, which is why coaching and therapy is a critical part of the treatment. A professional practitioner can welcome patients to embrace the effects and experience the benefits.

These short-term effects are well-documented and expected. A 2019 review in the Journal of Clinical Psychiatry found that most acute side effects of subanesthetic ketamine resolve within two hours of completion.

Here in our Livermore ketamine clinic, I always have patients rest in our clinic until they feel grounded. We don’t rush anyone out the door.

Long-Term Side Effects of Ketamine: What Does the Evidence Say?

This is where careful distinctions matter.

Most long-term side effect data comes from two populations: chronic recreational users (high doses, frequent use, no medical supervision) and chronic pain patients receiving ketamine over months or years.

In recreational users taking high doses repeatedly, the literature documents:

Urinary tract damage: Ketamine-induced cystitis can cause bladder pain, urgency, and in severe cases, permanent bladder damage. This is dose-dependent and typically seen with daily or near-daily abuse at high doses.
Cognitive effects: Some studies suggest memory impairment in heavy long-term users, though it’s difficult to separate ketamine’s effects from other factors like polysubstance use.
Hepatotoxicity: Liver enzyme elevations have been reported in chronic high-dose users.

Here’s the important context: therapeutic ketamine protocols use dramatically lower doses at much lower frequencies than recreational use. A typical treatment-resistant depression protocol might involve six sessions over three weeks, then occasional boosters. That’s a fundamentally different exposure pattern than daily recreational use.

In patients receiving therapeutic ketamine for depression or chronic pain, long-term adverse effects are relatively rare when treatment is properly monitored. A 2020 systematic review found that repeated low-dose ketamine infusions did not produce significant cognitive impairment or urinary symptoms at standard therapeutic doses.

That said, we still monitor. At Mind Balance Flow, I check in about urinary symptoms, cognitive concerns, and overall wellbeing at every visit. Patients coming from across the Bay Area expect that level of attentiveness in our clinic.

Dose-Dependent Effects: Low Dose vs. High Dose

Ketamine’s effects scale with dose. Understanding this helps demystify what you’ll experience. At Mind Balance Flow, we administer a dose referred to as subanesthetic, which is a dose much lower than what is given for anesthesia.

Low subanesthetic doses (typically 0.5 mg/kg for depression protocols) produce:

Mild to moderate dissociation
Possible perceptual changes
Preserved breathing and protective reflexes
- Translation: you’ll continue to breathe normally and have normal reactions that keep you from choking or gagging
Therapeutic neuroplasticity effects (enhanced BDNF, synaptogenesis)
- Translation: Patients with depression typically have low BDNF (Brain-Derived Neurotrophic Factor, which is essentially a growth protein for brain cells), shrinkage in certain areas of the brain, and fewer synapses between neurons. Ketamine helps to boost all of these.

Higher doses (approaching anesthetic levels) produce:

More profound dissociation (“K-hole” in recreational terminology)
Higher risk of nausea and psychological distress
Greater cardiovascular effects
Note: We do not use high doses in our clinic due to these effects.

Overdose (typically only possible with unsupervised use) can cause:

Severe respiratory depression
Dangerous drops in blood pressure
Unconsciousness
Risk of aspiration

In a clinical setting with proper monitoring, overdose is essentially not a concern. We calculate your dose based on your weight, adjust based on your response, and watch you throughout. It’s the difference between being in a swimming pool with a lifeguard versus swimming alone in the ocean at night.

Do Side Effects Differ Based on What Ketamine Is Treating?

This is a question I get often: “Are ketamine side effects for depression different than for pain?”

The short answer is no. The medication produces the same pharmacological effects regardless of indication. Ketamine blocks NMDA receptors, modulates glutamate signaling, and triggers downstream neuroplastic changes whether you’re treating depression, PTSD, anxiety, or chronic pain.

However, there are practical differences in how treatment protocols may differ:

Depression protocols typically use doses in the lower range. Side effects are predictable and generally mild.

Chronic pain protocols sometimes use higher doses. This can increase the intensity of dissociative effects and the likelihood of nausea. Some pain clinics use multi-hour or even multi-day infusions for conditions like complex regional pain syndrome (CRPS).

Psychological response may also differ. A patient with depression might experience emotional breakthroughs during treatment such as crying, insights, or memories surfacing. A patient primarily seeking pain relief might notice these less or attribute them to the relief of finally being pain-free.

The preparation we do also matters. Patients receiving ketamine for depression or trauma often benefit from integration support for processing what came up during the treatment. This doesn’t change the physical side effects, but it changes how the experience feels overall.

How Long Do the Effects of Ketamine Last?

This depends on which effects you’re asking about.

Acute dissociative effects typically last 45 to 90 minutes after the infusion ends. Some residual grogginess may persist for 2 to 4 hours.

Therapeutic antidepressant effects can begin within hours to days. Research suggests rapid improvement in depression scores, often within 24 hours for responders. The duration of benefit varies. Some patients feel better for days, others for weeks. This is why we follow up with patients and often recommend additional treatment sessions weeks to months after their initial 6 week treatment.

Neuroplasticity effects (the structural changes in brain connectivity) are harder to measure subjectively but likely persist longer than the mood effects. Studies using neuroimaging show changes in functional connectivity that correlate with clinical improvement.

For most patients at our Livermore clinic, the pattern looks like this: acute effects resolve same day, mood improvement becomes noticeable over the following week, and we plan boosters based on when symptoms start to return (often 3 to 6 weeks, though highly individual).

Ketamine Has Real Side Effects

The side effects of ketamine are generally manageable, time-limited, and far less severe than what many patients have already endured from years of treatment-resistant depression or chronic pain.

The most important factor is context. Therapeutic ketamine in a clinical setting with proper monitoring, personalized dosing, and integration support is fundamentally different from recreational use. The risks are dramatically lower. The benefits are more accessible.

If you’re in the Tri-Valley or East Bay, or greater Bay Area and considering ketamine treatment, I’d encourage you to schedule a consultation. Ask hard questions. Expect honest answers. That’s how good medicine should work.
We offer free consultations at Mind Balance Flow to help you determine if ketamine therapy is appropriate for your situation. You can schedule online here.