It’s actually not come across often. You say you’ve done research on it, so you probably know this recent Canadian study from 2021, which concludes it might help for fibromyalgia.
The side effects mentioned in the full article here Systematic Review of the Use of Intravenous Ketamine for Fibromyalgia don’t come close to those mentioned on wikipedia, which are “At lower sub-anesthetic doses, psychiatric side effects are prominent. A majority of patients feel strange, spacey, woozy or floating, or have visual distortions or numbness. Also very frequent (20–50%) are difficulty speaking, confusion, euphoria, drowsiness, and difficulty concentrating. The symptoms of psychosis such as going into a hole, disappearing, feeling melting, experiencing colors and hallucinations are described by 6–10% of people. Dizziness, blurred vision, dry mouth, hypertension, nausea, increased/decreased body temperature, or feeling flushed are the common (>10%) non-psychiatric side effects. All these adverse effects are most pronounced by the end of the injection, dramatically reduced 40 min after, and completely disappear within 4 hours after the injection.”
Having read that, I wouldn’t care that they completely disappear, I wouldn’t do it!
It’s been mentioned 11x here before (using the search tool up right) as something that was to be tried, but I can’t (on the fly) find any outcome reported, this is one example: Has anyone tried Ketamine infusions?.