Ketamine therapy typically produces a feeling of floating or detachment from your body, often accompanied by altered perception of time, unusual visual imagery, and a dreamlike state. Most people describe the experience as strange but tolerable, and the most intense effects last roughly 30 to 50 minutes depending on how the drug is delivered. The sensations can range from peaceful and expansive to disorienting, and no two sessions feel exactly the same.
The First Few Minutes
If you’re receiving ketamine through an IV, the most common method for depression treatment, the effects begin within seconds of the infusion starting. You’ll likely notice a subtle shift first: the room may seem slightly different, sounds might feel farther away, and your body may start to feel heavy or light. Within the first five to ten minutes, these sensations deepen noticeably. With intranasal esketamine (the FDA-approved nasal spray), absorption is slower and less complete, with peak blood levels reached around 40 minutes. The overall experience tends to be milder: dissociative effects occur in about 34% of nasal spray sessions compared to roughly 58% of IV sessions.
The standard therapeutic dose for depression is 0.5 mg/kg delivered over about 40 minutes, though some people respond to doses as low as 0.1 mg/kg and others need up to 0.75 mg/kg. That dose range is well below what’s used for surgical anesthesia, so you stay conscious throughout. You’re aware of your surroundings, but they feel distant, like watching yourself from the outside.
What the Peak Feels Like
The most intense part of the experience is often described using words like spacey, woozy, loopy, or bizarre. People frequently report a sensation of floating, as if gravity has loosened its grip. Time perception warps: a 40-minute infusion might feel like 10 minutes to one person and two hours to another. Some people experience vivid visual imagery with their eyes closed, geometric patterns, dreamlike scenes, or flowing colors. Others see very little but feel a profound sense of detachment from their usual thought patterns.
Researchers have noted that the experience goes beyond simple dissociation. People report unusual bodily sensations, a deep sense of peacefulness, feelings of unity or interconnectedness, and what some describe as a spiritual quality. There can also be moments of emotional intensity, where feelings surface unexpectedly. This is part of why many clinics use eye masks and curated music playlists during sessions. The music serves as an emotional anchor, helping guide your internal experience and giving your mind something to follow when your usual sense of self feels loosened.
Not everyone finds the peak pleasant. Some people feel anxiety or a sense of losing control, particularly during their first session. This tends to ease in subsequent treatments as you learn what to expect.
Physical Sensations During Treatment
Alongside the psychological effects, your body goes through measurable changes. Blood pressure and heart rate rise, peaking around 30 to 50 minutes into the session, with blood pressure increases ranging from 10 to 50% above your starting values. You may or may not feel this as a warmth or pressure in your chest and head. Clinics check your blood pressure before and after each session, and most require a pre-session reading below 150/90 to proceed.
Nausea is one of the more common physical side effects, which is why clinics ask you to avoid eating for at least two hours beforehand and stop drinking fluids 30 minutes before. Dizziness, blurred vision, and headache also occur but are generally mild. All of these physical effects are transient, resolving within two to four hours after the dose.
The Clinical Setting
The room itself is designed to feel safe and calm. Most ketamine clinics use dim lighting, comfortable recliners or beds, soft blankets, and pillows. You’ll typically be offered an eye mask and noise-canceling headphones playing a curated playlist. A nurse or medical provider stays nearby, monitoring your vital signs and available if you need reassurance. You’re not alone in the room, even though the experience itself is deeply internal.
Some clinics offer therapy alongside the ketamine session, with a therapist present to guide you through what comes up. Others provide the infusion in a purely medical setting and schedule a separate therapy appointment afterward. The format varies, but medical supervision during the session itself is standard.
How It Differs by Delivery Method
IV ketamine hits faster and harder than the nasal spray. It provides near-complete bioavailability, meaning almost all of the drug reaches your brain, producing a rapid and pronounced shift in consciousness. The nasal spray delivers roughly 54% of the drug to your bloodstream, and absorption varies depending on your nasal anatomy and how well the spray is administered. The result is a gentler, more gradual experience.
This difference shows up in clinical outcomes too. In one study, 47% of IV ketamine patients responded by the first week compared to 7% of those using the nasal spray. The median number of treatments to achieve remission was 2 for IV ketamine versus 7 for intranasal esketamine. IV ketamine also produces larger spikes in blood pressure and heart rate. If you’re trying to anticipate what your session will feel like, knowing which form you’re receiving matters a great deal.
Other routes exist as well, including oral lozenges (sublingual), intramuscular injections, and subcutaneous injections. Oral forms have lower bioavailability and produce a slower, less intense experience. Intramuscular injections fall somewhere between IV and nasal spray in terms of onset and intensity, with effects beginning in three to five minutes and peak levels reached within 5 to 30 minutes.
Coming Down and the Hours After
As the infusion ends or the drug wears off, the dissociative effects fade relatively quickly. Most people feel noticeably more grounded within 15 to 30 minutes after the IV stops, though a foggy, slightly dreamy quality can linger for another hour or two. Clinics typically keep you for observation until you’re steady on your feet and your blood pressure has returned to a normal range.
You won’t be able to drive yourself home. Ketamine slows your thinking and reaction time for hours afterward, and every clinic requires you to arrange a ride in advance. For the rest of the day, most people feel tired, emotionally open, and a bit mentally soft around the edges. Common experiences in the first 24 hours include mild fatigue or grogginess, emotional sensitivity, light brain fog, changes in sleep patterns, and a heightened sense of introspection. Many people describe this period as an “afterglow,” a window of emotional clarity or calm that can feel strikingly different from their usual depressive baseline.
This post-session window is considered valuable for therapeutic work. If you’re doing integration therapy, your therapist may schedule a session within a day or two to help you process whatever came up during the ketamine experience. The insights or emotional shifts that surface during treatment can fade if they’re not actively explored afterward.
Why It Feels the Way It Does
Ketamine blocks a specific type of receptor in the brain that normally responds to glutamate, the brain’s primary excitatory chemical messenger. Paradoxically, blocking these receptors at low doses triggers a surge of glutamate activity elsewhere, particularly in the prefrontal cortex, the region responsible for mood regulation, decision-making, and self-reflection. This surge activates other receptor types that kick off a cascade of changes, including the release of dopamine and the growth of new neural connections.
The dissociative, floating, dreamlike quality of the experience is a direct result of this disruption in normal brain signaling. Your brain’s default patterns of communication are temporarily scrambled, which is both what creates the strange subjective experience and, researchers believe, what allows new neural pathways to form. The feeling of detachment from your usual thought loops isn’t just a side effect. There’s growing evidence that the degree of dissociation during a session correlates with the antidepressant benefit, though this relationship is still being studied and debated.