Ketamine for Fibromyalgia, CRPS and Neuropathic Pain: Why Some Chronic Pain Behaves Differently

A broken bone hurts for an obvious reason.

There is injured tissue. The body sends a pain signal. The injury heals, and the pain usually fades.

Chronic neuropathic pain does not always behave that way.

The original injury may have healed months or years ago. Tests can look surprisingly normal. Yet burning, stabbing, electric, hypersensitive pain continues.

For patients living with conditions such as complex regional pain syndrome, neuropathic pain, or fibromyalgia, that disconnect can be one of the hardest parts of the illness.

People around them may assume:

“If the injury healed, why do you still hurt?”

The answer often involves the nervous system itself.

Ketamine is relevant because it acts on one of the pathways involved in persistent pain signaling.

KetaRevive currently offers IV ketamine for chronic and neuropathic pain, but this is an area where the site’s educational content can go substantially deeper. 

What Is Neuropathic Pain?

Neuropathic pain results from damage or dysfunction involving nerves or the somatosensory nervous system.

Patients often describe it differently from ordinary soreness.

Common words include:

• Burning

• Shooting

• Electric

• Pins and needles

• Stabbing

• Tingling

• Numbness combined with pain

• Extreme sensitivity to touch

Sometimes a light touch that should not hurt becomes intensely painful.

That symptom is called allodynia.

What Is CRPS?

Complex regional pain syndrome, or CRPS, is a difficult chronic pain condition often developing after an injury, surgery, or trauma.

Pain can be much greater than expected from the original injury.

Patients may also experience:

• Swelling

• Skin temperature changes

• Color changes

• Altered sweating

• Severe sensitivity

• Stiffness

• Changes in hair or nail growth

• Difficulty moving the affected limb

CRPS can become deeply disabling.

It is also one of the pain syndromes in which ketamine has received significant clinical attention.

A 2024 systematic review and meta-analysis examining pharmacologic treatments for CRPS found evidence that ketamine can reduce pain beyond one month, although the certainty of that evidence was rated low. 

That is useful evidence.

It is not the same thing as certainty.

What About Fibromyalgia?

Fibromyalgia is more diffuse.

Patients may experience widespread pain, fatigue, sleep disturbance, cognitive symptoms, and sensitivity throughout the body.

Researchers have investigated ketamine because of its effect on NMDA-receptor signaling and central sensitization.

A 2024 systematic review identified only six eligible studies involving a total of 115 fibromyalgia patients. Most of the short-term studies found improvement in pain, but longer-term evidence was limited. The authors concluded that additional research with longer follow-up is needed. 

That is exactly the kind of finding patients deserve to hear in full.

There is a signal.

The research base is small.

Why Does Ketamine Affect Pain?

Ketamine blocks NMDA receptors.

Those receptors are involved in glutamate signaling, which participates in pain transmission and sensitization.

When pain persists long enough, the nervous system can effectively become better at producing pain.

The threshold falls.

The amplification rises.

A normal sensation can become uncomfortable.

An uncomfortable sensation can become unbearable.

Ketamine may interrupt portions of that process.

This helps explain why the dosing and treatment protocols used for pain can differ from those used for depression.

Chronic Pain and Depression Are Related, But Not Identical

Living with pain changes life.

People stop exercising because movement hurts.

Sleep becomes fragmented.

Social plans become harder.

Work becomes unpredictable.

Then depression or anxiety may appear.

Sometimes clinicians make the mistake of assuming that because depression accompanies chronic pain, the pain itself must be psychological.

That is an oversimplification.

Pain, mood, sleep, and stress affect each other through overlapping systems.

Ketamine is unusual because it has been investigated across both psychiatric and pain indications.

Still, outcomes should be measured separately.

A patient might report improved mood while pain remains unchanged.

Another might experience reduced pain but continue struggling emotionally.

Both are clinically possible.

What Conditions Fall Under Neuropathic Pain?

Neuropathic pain can arise from many causes, including:

• Nerve injury

• Diabetes

• Surgery

• Certain infections

• Chemotherapy

• Spinal conditions

• CRPS

• Other neurologic disorders

A 2024 systematic review and meta-analysis examined ketamine across multifactorial neuropathic pain conditions, reflecting the continuing clinical interest in NMDA-receptor blockade for difficult pain syndromes. 

Because neuropathic pain has many causes, “ketamine for nerve pain” is not a diagnosis.

The cause still matters.

Who Should Be Evaluated Before Considering an Infusion?

A pain consultation should establish:

• The diagnosis

• Duration of symptoms

• Previous treatments

• Functional limitations

• Current pain medications

• Opioid use if applicable

• Neurologic findings

• Cardiovascular history

• Psychiatric history

• Treatment goals

Ketamine should not substitute for identifying a treatable structural or neurologic problem.

A person with newly progressive weakness, for example, needs diagnostic evaluation.

What Does Success Look Like?

Patients understandably want pain to go to zero.

That is sometimes unrealistic in long-standing chronic pain.

Meaningful improvement may instead look like:

Pain falling from an eight to a four.

Sleeping six hours instead of three.

Walking through a grocery store again.

Returning to physical therapy.

Using less rescue medication.

Working a full day.

Playing with your children without calculating every movement.

Function matters.

In chronic pain medicine, a modest numerical pain reduction can be very meaningful if life expands around it.

How Long Can Relief Last?

This varies significantly.

Some research demonstrates short-term pain reduction. Certain CRPS studies suggest longer benefit in some patients. Fibromyalgia research is substantially thinner, especially over longer follow-up. 

A responsible clinic should therefore avoid promising that a particular infusion series will produce a specific duration of relief.

Response needs to be observed.

What Else Should Be Part of Treatment?

For many chronic pain conditions, the best plan is multimodal.

Depending on diagnosis, that may include:

• Physical therapy

• Occupational therapy

• Sleep treatment

• Appropriate medication

• Psychological support for coping with chronic illness

• Movement rehabilitation

• Interventional pain procedures

• Treatment of underlying disease

Ketamine can be one component without pretending to be the entire solution.

The Bottom Line

Ketamine has a legitimate place in the conversation about selected chronic pain conditions.

Research suggests potential benefit in CRPS, neuropathic pain, and fibromyalgia, but the strength of evidence differs substantially by condition. Fibromyalgia studies remain small. CRPS evidence is encouraging but not definitive. 

For patients who have already exhausted conventional approaches, the relevant question is not simply whether ketamine “works for pain.”

It is more specific:

What type of pain is this, what is driving it, what has already failed, and is NMDA-directed treatment a reasonable next step?

That is a much better place to begin.

Suggested internal links

• Chronic and neuropathic pain IV ketamine service

• Migraine/headache treatment page

• What a ketamine infusion feels like

• Consultation page