Ketamine therapy feels different from anything most people have experienced in a medical setting. During a session, you’ll likely feel a sense of floating or detachment from your body, altered perception of time, and sometimes a dreamlike state that can range from peaceful to strange. The entire appointment, from check-in to walking out the door, typically takes a couple of hours, though the drug’s active effects last roughly 40 to 60 minutes.
What the Session Feels Like
The most common descriptions patients give are feeling “spacey,” “floaty,” “loopy,” or like they’re dreaming while still awake. You remain conscious but feel disconnected from your surroundings and your body in a way that can be disorienting at first. Time perception shifts noticeably: a 40-minute infusion might feel like 15 minutes or two hours, depending on the person.
Beyond basic dissociation, many people report experiences that are harder to pin down. Some describe a profound sense of peacefulness or unity, unusual bodily sensations like warmth or tingling, or vivid internal imagery with eyes closed. Others feel disinhibited, emotionally open, or have what they describe as spiritual experiences. Not everyone finds the experience pleasant. Some sessions feel bizarre or uncomfortable, and the intensity can vary from one treatment to the next even for the same person.
The dissociative effects begin within minutes of starting an IV infusion and peak about midway through. As the infusion ends, they fade relatively quickly. Most people feel mostly normal within 30 to 60 minutes after the drip stops, though some grogginess and mild coordination issues can linger for a few hours.
How a Typical Appointment Works
You’ll arrive at a clinic and have your vital signs checked, including blood pressure. This matters because ketamine can cause significant blood pressure spikes during treatment, particularly if you’re older or already have elevated blood pressure. Your blood pressure is typically recorded every 10 minutes throughout the session.
For IV ketamine, the standard dose is administered over 40 to 100 minutes. You’ll sit or recline in a comfortable room, often with the option to listen to music or use an eye mask. A clinician monitors you throughout. The nasal spray version (esketamine, brand name Spravato) is self-administered under supervision, with sessions involving 56 or 84 milligrams sprayed in a series of puffs.
After the active treatment ends, you stay at the clinic for an observation period while staff check that your blood pressure has normalized and you’re alert enough to leave. You won’t be allowed to drive yourself home, so plan for someone to pick you up. Most people feel well enough to eat and move around normally by the evening, though some report fatigue or mild fogginess for the rest of the day.
IV Ketamine vs. Nasal Spray
The two main options are IV ketamine, which clinics compound and administer off-label, and the FDA-approved nasal spray esketamine. Both produce similar response and remission rates for treatment-resistant depression. The practical difference is speed: in one study from the Mayo Clinic, IV ketamine achieved remission in significantly fewer treatments than the nasal spray, roughly five times faster when adjusted for patient characteristics.
A typical course involves 3 to 6 IV ketamine sessions or 6 to 8 nasal spray sessions before a clinician reassesses whether the treatment is working. IV sessions are usually scheduled two to three times per week during this initial loading phase. The nasal spray follows a similar twice-weekly schedule initially, then tapers to weekly or biweekly. Guidelines generally recommend a maximum treatment duration of 12 weeks for a given course.
When You Might Notice a Difference
Unlike traditional antidepressants that take weeks to build up, ketamine can produce noticeable mood shifts within hours or days of a single session. Some people describe it as a lifting of heaviness or a quieting of relentless negative thoughts. This rapid effect is one of the main reasons ketamine has generated so much interest for severe depression.
The catch is that these effects are often temporary after a single session. The loading phase of multiple treatments over two to three weeks is designed to build a more sustained response. Clinicians typically reassess after the initial series to determine whether you’re responding and what a maintenance schedule might look like. Some people do well with occasional booster sessions every few weeks; others find the benefits fade more quickly.
How It Works in the Brain
Ketamine works differently from standard antidepressants. Rather than adjusting serotonin or norepinephrine levels, it blocks a specific receptor involved in how brain cells communicate. This triggers a cascade that strengthens connections between neurons, particularly in areas of the brain involved in mood and memory. The drug essentially promotes the brain’s ability to form new neural pathways, a process called neuroplasticity, which may explain both the rapid effects and why benefits can persist beyond the drug’s presence in the body.
Common Side Effects
The most frequently reported side effects during a session are nausea, dizziness, disorientation, and temporary increases in blood pressure. Some people experience brief visual disturbances or hallucination-like imagery. These effects are transient, resolving within an hour or two after treatment ends. Many clinics offer anti-nausea medication beforehand if you’re prone to queasiness, and fasting for a few hours before your session helps.
Serious adverse events are rare. A systematic review of studies involving over 3,700 patients found that medically serious complications occurred in approximately 0.1% of people receiving sub-anesthetic ketamine, and no serious cardiac events or deaths were observed. That said, most clinical trials exclude people with high cardiovascular risk, so these numbers reflect a pre-screened population.
Who Shouldn’t Receive Ketamine
Several conditions make ketamine therapy inadvisable. Poorly controlled cardiovascular disease is the most significant concern, since the drug raises heart rate and blood pressure. A history of psychosis, including schizophrenia, is a contraindication because ketamine can reactivate hallucinations or delusions. Other exclusions include elevated pressure in the brain or eyes, severe liver disease, active delirium, and current substance use disorders given ketamine’s recognized abuse potential.
Before your first session, you’ll go through a medical and psychiatric screening. This typically includes a review of your cardiovascular health, mental health history, current medications, and any history of substance use. The goal is to ensure the treatment is safe for your specific situation, not just effective in general.