Ketamine for Chronic Pain

 

Ketamine for Chronic Pain Summary

Research into Ketamine for pain management shows it to be a safe alternative to opioids in emergency settings. A 2025 study has shown that 20-46% of patients achieved clinically meaningful improvements in pain management and found the benefits were sustained 6 months post treatment. A 2025 study found Ketamine to match the effect of opioids for immediate pain relief without the side effects. Overall the studies show that Ketamine is an effective tool for treating pain.

Chronic pain is typically categorized as mild to severe pain that persists or progresses in severity over an extended period of time(about 6 months). According to studies about 20% of American adults are suffering from chronic pain.

The symptoms associated with chronic pain can be debilitating and can interfere with a person's day-to-day activities. Tasks that could be done with little effort in the past can become grueling and painful. This has also a chance of triggering depression and anxiety, which makes Ketamine a good option for Chronic pain, because it can do both help with the pain and alleviate depression very quickly.

Note: Ketamine is FDA approved for general use in anesthesia and as of August 2025 it is approved for surgical pain management in perioperative settings.

1) Mechanism of Action

Ketamine is used as an analgesic, especially for severe acute pain and selected chronic pain syndromes.

  • NMDA receptor antagonism causes a reduction in glutamate-mediated pain transmission
  • Decreases central sensitization
  • Inhibits the wind-up phenomenon (progressive amplification of pain signals)
  • Enhances descending inhibitory pain pathways

These effects are especially relevant in neuropathic pain and opioid-resistant pain.

2) Clinical Indications

  • Neuropathic pain (for example, complex regional pain syndrome)
  • Cancer-related pain
  • Fibromyalgia
  • Opioid-tolerant or opioid-resistant pain

Ketamine is often used as an adjunct rather than a first-line analgesic.

3) Clinical Effects

  • Rapid analgesia
  • Improved pain control in opioid-resistant cases
  • Reduction in pain intensity
  • Reduction in hyperalgesia and allodynia
  • Improved quality of life in some patients

In chronic pain, ketamine may sometimes provide relief that lasts beyond the infusion period by helping reset abnormal pain processing and can last for days and even weeks after the ketamine session.

4) Potential Advantages

  • Effective in opioid-resistant pain
  • Opioid-sparing, which may reduce opioid adverse effects and opioid dose requirements
  • Minimal respiratory depression
  • Useful in some hemodynamically unstable patients
  • Treats both the pain and depression

These features make ketamine valuable in emergency, perioperative, and selected chronic pain settings.

5) Limitations and Risks

  • Variable response in chronic pain patients
  • Short duration of benefit in some cases
  • Need for monitoring at higher doses
  • Potential for misuse or dependence

6) Adverse Effects

  • Dissociation
  • Hallucinations or perceptual disturbances
  • Dizziness
  • Nausea/vomiting
  • Sedation
  • Increased blood pressure and heart rate

With repeated or long-term use

  • Cystitis (ketamine bladder syndrome)
  • Cognitive effects
  • Potential hepatotoxicity

7) Current Clinical Role

  • Used in palliative care and oncology pain management
  • Reserved for refractory cancer pain
  • Typically used as an adjunct to other analgesics