Yes, ketamine has measurable anti-inflammatory effects. At sub-anesthetic doses, it reduces key inflammatory markers in both the bloodstream and the brain, with effects detectable within 40 minutes of administration. This property is separate from its better-known roles as an anesthetic and rapid-acting antidepressant, though researchers increasingly believe the anti-inflammatory action may help explain why ketamine works so well for depression and certain pain conditions.
Which Inflammatory Markers Does Ketamine Lower?
Ketamine consistently reduces three of the body’s most important inflammatory signaling molecules: IL-6, IL-1β, and TNF-α. These are the same markers that rise during infection, chronic stress, autoimmune flares, and surgical trauma. In animal studies, ketamine lowered IL-1β in 14 out of 19 experiments and IL-6 in 13 out of 18. Human evidence is more variable, but most clinical trials show decreases in all three markers.
In one study of patients receiving a single ketamine infusion, TNF-α levels dropped significantly within 40 minutes and remained suppressed at the four-hour mark. IL-6 showed significant decreases starting around four hours after infusion and lasting up to three days. In patients who received a series of six ketamine infusions over two weeks, IL-6, TNF-α, and IL-1β were all significantly lower at 14 days compared to baseline.
Ketamine also lowers C-reactive protein (CRP), a broad marker of systemic inflammation. In a study of patients undergoing emergency cesarean section, the group that received low-dose ketamine saw their CRP rise about 4.7 times after surgery, while the group without ketamine saw an 8.6-fold increase. Both groups started with similar CRP levels beforehand.
How Ketamine Reduces Inflammation
Ketamine works through at least two anti-inflammatory pathways. First, it activates what’s called the cholinergic anti-inflammatory pathway by stimulating a specific receptor on nerve cells. This blocks a major inflammation cascade (the TLR4/NF-κB pathway) that cells use to ramp up production of inflammatory molecules. By preventing a key protein called P65 from entering the cell nucleus, ketamine essentially stops the cell from turning on its inflammation genes.
Second, by lowering IL-1β, IL-6, and TNF-α, ketamine indirectly reduces the activity of an enzyme that diverts tryptophan away from serotonin production and toward neurotoxic byproducts. This is particularly relevant in depression: when inflammation is high, more tryptophan gets converted into compounds that damage neurons rather than into serotonin. Ketamine shifts this balance back toward neuroprotective pathways.
The Connection to Depression
There is strong evidence that chronic inflammation plays a role in initiating and maintaining major depressive disorder. Many people with treatment-resistant depression have elevated inflammatory markers, and ketamine’s rapid antidepressant effect may be partly driven by its ability to quiet that inflammation. In one clinical trial, the speed at which TNF-α dropped in the first 40 minutes after a ketamine infusion correlated directly with how much a patient’s depression scores improved over the following days.
A 2025 study published in Molecular Psychiatry showed that ketamine reduced infiltration of immune cells into the brain and dampened activation of microglia, the brain’s resident immune cells. Overactive microglia are a hallmark of neuroinflammation and have been linked to depression, chronic pain, and neurodegeneration. In that study, the anti-inflammatory effects and the antidepressant effects appeared to be linked, suggesting they may be convergent outcomes of the same mechanism rather than separate actions.
Doses That Produce Anti-Inflammatory Effects
The anti-inflammatory effects occur at sub-anesthetic doses, meaning doses far below what would be used for surgical anesthesia. The typical range studied for both pain relief and inflammation reduction is 0.15 to 0.5 mg/kg given intravenously. For context, a 70 kg (154 lb) person would receive roughly 10 to 35 mg as a single dose, compared to the 100+ mg that might be used for anesthesia. Continuous infusions are typically run at 0.15 to 0.3 mg/kg per hour.
These low doses are the same ones used in ketamine clinics for depression and chronic pain, which means patients receiving ketamine for those conditions are likely getting anti-inflammatory benefits as part of the package.
Anti-Inflammatory Effects in Surgery
Surgery triggers a massive inflammatory response, and several studies have tested whether adding low-dose ketamine to anesthesia can blunt that response. The cesarean section study is one example: postoperative CRP averaged 32.3 mg/L in the ketamine group versus 72.1 mg/L in the placebo group, a meaningful difference. Ketamine given before general anesthesia has also been shown to decrease secretion of IL-6 and TNF-α while maintaining levels of IL-2, a cytokine important for balanced immune function.
When combined with dexamethasone (a standard anti-inflammatory steroid), ketamine produced better results than either drug alone for reducing post-surgical sore throat and hoarseness, two conditions driven by local inflammation from intubation.
Ketamine Can Also Cause Inflammation
There is an important caveat. While low-dose, medically supervised ketamine reduces systemic inflammation, frequent or high-dose use, particularly recreational use, can cause severe localized inflammation in the bladder. This condition, called ketamine-induced cystitis, involves chronic bladder inflammation with symptoms including urinary urgency, painful urination, frequent urination, and blood in the urine.
About 20% of frequent recreational ketamine users report cystitis symptoms, compared to roughly 7% of infrequent users. Regular use increases the risk of cystitis 3 to 4 times over baseline. The severity correlates directly with dose and frequency. In extreme cases, prolonged use can lead to bladder wall fibrosis, reflux of urine back toward the kidneys, and even chronic kidney failure. The mechanism appears to involve inflammatory pathways triggered by ketamine’s breakdown products as they pass through the urinary tract and damage the bladder lining.
Stopping ketamine use typically improves symptoms, but the damage from extended heavy use can be permanent. This is primarily a concern with recreational use patterns rather than the controlled, low-dose protocols used in clinical settings.
How It Compares to Traditional Anti-Inflammatories
Ketamine is not a replacement for conventional anti-inflammatory drugs. It works through entirely different mechanisms than NSAIDs (which block prostaglandin production) or corticosteroids (which broadly suppress immune activity). Its anti-inflammatory effects are real but more targeted, primarily affecting specific cytokines and neuroinflammatory pathways rather than suppressing the immune system broadly.
The clinical significance lies not in using ketamine as a standalone anti-inflammatory, but in recognizing that its anti-inflammatory properties contribute to its effectiveness for depression, chronic pain, and perioperative care. For patients with inflammation-driven depression or pain conditions where traditional treatments have failed, ketamine’s ability to rapidly suppress neuroinflammation within minutes may be part of what makes it uniquely effective.