What Does Ketamine Therapy Feel Like?

Ketamine therapy is used to treat chronic pain, anxiety and treatment-resistant depression. An estimated 1.6 million Americans received some form of ketamine therapy in 2024, according to one national survey [1].

Treatment involves low doses of the anesthetic, given over a series of sessions that can run for weeks or months, most often by intravenous (IV) drip, intramuscular (IM) injection, or nasal spray. In a medical setting, under a licensed physician's supervision, ketamine is legal and safe.

Many people also know ketamine as a recreational drug, which is understandably part of why they're curious what ketamine therapy actually feels like and how it works. Here's what to know.

What Is Ketamine Therapy?

Ketamine therapy is FDA-approved, in its esketamine form, for treatment-resistant depression, and used off-label for depression, anxiety and suicidal ideation more broadly. It works by giving low doses slowly, across repeat sessions over days or months, depending on how someone responds and how severe their condition is.

Research has found that ketamine therapy can produce meaningful improvements for people with treatment-resistant depression, including reductions in self-harm, suicidal ideation and anxiety [2]. In one University of Michigan–covered study, more than half of participants saw severe depression symptoms ease to the point of remission after three infusions over 11 days [3] — a notable finding, though from a single study rather than a settled, general result. In a separate review, prolonged ketamine infusions (given over four to fourteen days) were linked to pain relief lasting up to three months for some people with chronic pain, though the benefit tended to fade within about a month and didn't always translate into better day-to-day functioning [4].

How Does Ketamine Therapy Feel?

Ketamine is a fast-acting dissociative anesthetic — it temporarily blocks nerve signals and dulls pain, sensation or awareness. A typical IV dose runs around 0.5 mg/kg over 40 minutes.

People who've had ketamine therapy commonly describe:

Side effects are possible but uncommon. The most common include dizziness, nausea, vomiting, a faster heart rate, blurred or double vision, anxiety, fatigue and headaches. Research has found that around 30% of people receiving ketamine therapy experience side effects, typically lasting only a few hours after treatment [5]. More serious but rarer effects include sharp blood pressure spikes, respiratory issues, bladder damage and psychotic symptoms such as hallucinations.

How Does Ketamine Therapy Work?

Researchers are still working out exactly how ketamine works, but one leading explanation is that it blocks certain glutamate signals in the brain, which gives neurons a chance to form new, healthy connections — a process called synaptogenesis [6]. Over time that supports neuroplasticity, the brain's ability to adapt and build new pathways, which may make it easier to think and feel differently.

Unlike antidepressants such as SSRIs, which target serotonin, ketamine's effect on glutamate signaling is thought to help neurons communicate, learn and form new connections more directly — part of why its effects can show up faster, sometimes easing mood and suicidal ideation within hours.

It's worth noting that ketamine therapy isn't a first-line treatment. It's typically considered after standard medications, such as mood stabilizers, and psychotherapy haven't worked well enough on their own, and most ketamine therapy happens alongside continued therapy such as CBT.

Is Ketamine Therapy Legal?

Ketamine therapy is legal when given at a licensed clinic with DEA registration. In its IV and IM forms, ketamine is FDA-approved only for use in major surgeries — physicians can prescribe it "off-label" for mental health purposes based on their own clinical judgment.

Esketamine, sold as Spravato, is a nasal spray derived from ketamine and is the FDA-approved form specifically for treatment-resistant depression.

How Is Ketamine Therapy Structured at CMHS?

At Colorado Mental Health Services, ketamine treatment is structured as a series of IM infusions, most commonly six infusions over two to three weeks. A single, one-off infusion is also an option when that fits someone's situation better. Maintenance and booster sessions can follow either approach, to help sustain benefits already seen — see our article on what ketamine maintenance therapy involves for more on that.

Broadly, treatment moves through three phases: induction (a series of infusions over a few weeks, when most people see initial change), stabilization (infusions spaced further apart, to check whether the change holds), and maintenance (long-term, spaced-out infusions to sustain gains without total reliance on ongoing treatment). However it's structured, our medical team, led by Dr. Arshad William, M.D., monitors progress closely and builds a broader plan around it, including psychotherapy or other care as needed.

Ketamine at CMHS is self-pay and separate from our intensive outpatient program — you don't need to be enrolled in the program to ask about it. Eligibility is always decided after medical screening, not before.

Ketamine Therapy at Colorado Mental Health Services, Lakewood, CO

If you're navigating your mental health right now, you're not alone, and our team has years of experience supporting people through it.

From our center in Lakewood, Colorado, we offer IV and IM ketamine treatment for people struggling with treatment-resistant depression, anxiety and PTSD. We hold a DEA license, stay current on the latest research, and build an induction, stabilization and maintenance plan around each person's needs — always prioritizing safety and comfort.

Call our admissions team when you're ready, or start by reaching out online.