Ketamine Therapy Side Effects: What to Expect During and After Treatment

Ketamine therapy can cause side effects during treatment and for a period afterward. Common effects include dissociation, dizziness, nausea, sedation, changes in perception, and temporary increases in blood pressure.

Most of these effects happen during the treatment session or shortly afterward. How strong they feel can depend on the dose, treatment method, other medications, and your individual response.

Spravato and IV ketamine also have some differences in their side effect profiles and monitoring requirements.

If you're considering treatment, here's what you should know about the side effects you may experience and which symptoms deserve more attention.

What Are the Most Common Side Effects of Ketamine Therapy?

The side effects people experience most often tend to affect perception, balance, alertness, blood pressure, and the stomach.

Not everyone experiences the same effects.

Some people feel only mildly different during a session. Others experience noticeable dissociation, dizziness, or sedation.

A 2025 systematic review found dizziness, dissociation, nausea, sedation, blood pressure increases, vertigo, and blurred vision among the more common effects reported with ketamine or esketamine.

Dissociation Can Feel Strange, but It Isn't Always a Sign Something Is Wrong

Dissociation is one of the side effects most closely associated with ketamine treatment.

It can feel like you're separated from your body, watching yourself from a distance, or experiencing the room differently than usual.

Your sense of time may change. Sounds or visual details may seem different. Some people describe the experience as dreamlike or feel less connected to their surroundings.

These sensations can be mild or intense.

Spravato's FDA prescribing information specifically warns about dissociation and perceptual changes. These effects are one reason patients are observed after receiving the medication.

If you're nervous about the experience itself, our guide to what to expect at your first ketamine session explains what typically happens from arrival through recovery.

Dizziness and Poor Coordination Are Common During Recovery

Ketamine can temporarily affect balance, coordination, attention, and reaction time.

You may feel lightheaded when sitting up or standing. Some people feel as though the room is spinning.

This is one reason you shouldn't plan to drive yourself home after treatment.

Spravato has a specific FDA restriction. Patients shouldn't drive or operate machinery until the next day after a restful sleep.

Instructions after IV or IM ketamine can differ by clinic. Follow the discharge instructions given by your treating provider.

Nausea and Vomiting Can Occur

Nausea is another commonly reported side effect of ketamine and Spravato.

Some patients also vomit, although this is less common.

Clinics may give you instructions about eating and drinking before treatment. Follow your clinic's directions rather than assuming every treatment has the same fasting rules.

Spravato has specific instructions because nausea and vomiting can occur. Patients are told not to eat for at least two hours before treatment.

They are also told not to drink liquids for at least 30 minutes before treatment.

A provider may also use medication to help control nausea when appropriate.

You May Feel Sleepy or Mentally Foggy After Treatment

Sedation can range from feeling relaxed and tired to feeling unusually sleepy.

Attention and reaction time may also be impaired for a period after treatment.

You shouldn't assume that feeling awake means you're ready to drive, work, or make important decisions.

Plan for recovery time after your appointment and follow the clinic's transportation instructions.

Ketamine Can Temporarily Raise Blood Pressure

Both ketamine and Spravato can increase blood pressure.

You might not feel this happening, which is why clinics measure blood pressure instead of relying on symptoms alone.

Spravato providers check blood pressure before treatment and again afterward. The FDA requires monitoring for at least two hours after each Spravato session.

IV ketamine providers also monitor vital signs during treatment.

Blood pressure changes are especially important for people with certain cardiovascular conditions. Your provider should review your medical history before approving treatment.

How Long Do Ketamine Side Effects Last?

Many of the most noticeable side effects occur during the treatment session and decrease during the recovery period.

Dissociation, dizziness, altered perception, and sedation often begin soon after treatment starts.

Some people continue to feel tired, foggy, mildly dizzy, or different for several hours afterward.

Spravato's patient information states that common side effects usually occur shortly after treatment and go away the same day.

That doesn't mean every patient follows the same timeline.

Dose, treatment method, other medications, and individual sensitivity can all affect how long you feel different.

If symptoms last much longer than your clinic told you to expect, contact the provider who treated you.

Are IV Ketamine and Spravato Side Effects Different?

There is considerable overlap, but the two treatments aren't identical.

Spravato contains esketamine and is given as a nasal spray in certified healthcare settings.

IV ketamine uses ketamine given directly into a vein. Its psychiatric use is off-label.

If you're choosing between them, read our full comparison of IV ketamine vs. Spravato.

IV Ketamine Side Effects

Commonly reported effects with ketamine include:

• Dissociation
• Changes in perception
• Increased blood pressure and heart rate
• Dizziness
• Nausea and vomiting
• Blurred or double vision
• Sleepiness
• Confusion or agitation during recovery

The exact experience varies with dose and how the medication is administered.

IV administration also gives the treating clinician direct control over the infusion rate.

If you're specifically looking for this treatment, browse ketamine infusion clinics.

Spravato Side Effects

The FDA lists several common adverse reactions with Spravato.

They include:

• Dissociation
• Dizziness
• Nausea
• Sedation
• Vertigo
• Numbness or reduced sensation
• Anxiety
• Lethargy
• Increased blood pressure
• Vomiting
• Feeling intoxicated
• Headache

Spravato can also cause a bad or unusual taste in the mouth.

Because of the risks of sedation, dissociation, and respiratory depression, patients must be monitored for at least two hours after each treatment.

Spravato is available only through certified healthcare settings under the FDA's REMS safety program.

You can browse Spravato treatment centers in the KetamineFinder directory.

Are There Serious Side Effects of Ketamine Therapy?

Serious reactions are less common than temporary effects such as dizziness or dissociation, but they can happen.

Risks that providers watch for include:

• Significant increases in blood pressure
• Severe sedation
• Respiratory depression
• Severe confusion or agitation
• Abnormal heart rate or rhythm
• Allergic reactions
• Problems related to abuse or misuse

Spravato carries boxed warnings for sedation, dissociation, respiratory depression, abuse and misuse, and suicidal thoughts and behaviors in certain patients.

Ketamine injection labeling also warns about blood pressure changes, respiratory depression, and other serious reactions.

This is why medical screening and monitoring matter.

A clinic should know your medications, health history, and relevant medical conditions before treatment begins.

What About Bladder and Urinary Problems?

Ketamine has been linked to bladder and urinary tract problems, especially with frequent or prolonged exposure.

Reported problems include:

• Painful urination
• Increased urinary frequency
• Urgency
• Blood in the urine
• Bladder inflammation
• Reduced bladder capacity

Much of the strongest evidence comes from chronic heavy ketamine exposure and misuse.

That isn't the same exposure pattern used in most medically supervised psychiatric treatment.

However, current ketamine labeling also notes urinary and bladder problems associated with chronic use.

Spravato labeling includes a warning about ulcerative or interstitial cystitis and recommends monitoring for urinary symptoms during treatment.

Tell your provider if you develop new urinary symptoms during a treatment course.

Can Repeated Ketamine Treatment Affect the Liver?

Repeated ketamine exposure has also been associated with liver and bile duct problems.

Current ketamine injection labeling includes warnings about drug-induced liver injury and hepatobiliary dysfunction with recurrent use.

The risk isn't the same for every patient or every treatment schedule.

That labeling recommends baseline liver function tests for patients on a treatment plan that uses recurrent dosing, with periodic monitoring during treatment.

Don't start or stop treatment based on a general side effect list. Discuss your individual risks with the clinician treating you.

Can Ketamine Affect Memory or Thinking?

Short-term changes in attention, reaction time, and thinking can occur around the treatment session.

Spravato studies found temporary cognitive impairment shortly after a dose, with performance returning to baseline about two hours later.

The longer-term question is less straightforward.

Current evidence from medically supervised treatment hasn't shown the same pattern associated with chronic heavy recreational ketamine use.

Researchers are still studying the effects of repeated psychiatric treatment over longer periods.

What Can Increase the Risk of Side Effects?

Your response to ketamine depends on more than the medication itself.

Factors that may affect side effects include:

• Dose
• Route of administration
• Other medications
• Alcohol or other substances
• Blood pressure
• Cardiovascular history
• Previous reactions to ketamine
• Individual sensitivity
• Other medical or psychiatric conditions

Certain medications can also increase sedation or affect blood pressure.

Give your provider a complete medication and supplement list before treatment.

Don't leave out alcohol, recreational drugs, or medications taken only occasionally. Those details can change how a clinician plans and monitors treatment.

When Should You Contact Your Ketamine Provider?

Your clinic should tell you which side effects are expected and what to do if they persist.

Contact the clinic if symptoms are stronger than expected, last longer than expected, or concern you after you leave.

Seek urgent medical care for severe symptoms such as trouble breathing, chest pain, seizures, loss of consciousness, or a sudden severe headache.

Spravato's FDA information specifically warns patients to report symptoms that could indicate a dangerous blood pressure increase.

These include chest pain, shortness of breath, sudden severe headache, changes in vision, and seizures.

Follow the emergency instructions given by your own provider.

How Clinics Reduce and Monitor Side Effects

Side effect management begins before the medication is given.

A well-run clinic should have a clear process for screening, monitoring, recovery, and responding to unexpected reactions.

Depending on the treatment, that may include:

• Reviewing your medical and psychiatric history
• Reviewing medications and substance use
• Checking blood pressure before treatment
• Monitoring blood pressure and heart rate
• Watching your level of alertness
• Monitoring breathing when appropriate
• Adjusting treatment based on your response
• Observing you during recovery
• Giving clear transportation and discharge instructions

Monitoring protocols differ between Spravato, IV ketamine, IM ketamine, and other treatments.

When comparing providers, our guide to how to choose a ketamine clinic explains what to look for before scheduling.

Side Effects Are One Part of Choosing the Right Treatment

Ketamine and Spravato can cause noticeable short-term effects, particularly dissociation, dizziness, sedation, nausea, and blood pressure changes.

Most patients receiving in-person treatment are monitored while these effects are most likely to occur.

The risks also aren't identical across every treatment method or every patient.

Your medical history, medications, treatment type, and dose all matter.

If you're considering treatment, start by discussing those factors with a qualified provider who can assess whether ketamine or Spravato is appropriate for you.

You can find ketamine clinics near you, browse Spravato treatment centers, or search ketamine infusion clinics.

If you're still learning how the treatments work, start with our guide to what ketamine therapy is and how it works.