Is gabapentin (anticonvulsant) used to treat fibromyalgia?

Is Gabapentin Used for Fibromyalgia?

Yes, gabapentin is used for fibromyalgia and is FDA-approved for this indication, though pregabalin is the more commonly recommended first-line anticonvulsant due to stronger evidence. 1

FDA Approval Status and Clinical Use

• Gabapentin is FDA-approved for fibromyalgia treatment, as confirmed by the CDC guidelines on chronic pain management 1
• Both gabapentin and pregabalin work by binding to calcium channels (α2δ subunits) in the brain and spinal cord, inhibiting release of excitatory neurotransmitters involved in pain 1
• The most bothersome side effects are somnolence, dizziness, and weight gain 1

Position in Treatment Algorithm

Gabapentin should be considered as a second-line pharmacological option after non-pharmacological interventions have been tried for 4-6 weeks. 2

First-Line Approach (Non-Pharmacological)

• Start with patient education about central sensitization followed immediately by graduated exercise programs (10-15 minutes of walking, swimming, or cycling, 2-3 times weekly) 2
• Add cognitive behavioral therapy for patients with mood disorders, depression, anxiety, or maladaptive coping strategies 2

Second-Line Pharmacological Options

• If non-pharmacological interventions provide insufficient relief after 4-6 weeks, add amitriptyline, duloxetine, or pregabalin as first-line medications 2
• Gabapentin is considered an alternative to pregabalin as it shares a similar mechanism of action, though it is not as commonly recommended as pregabalin in guidelines 3

Evidence Quality and Efficacy

The evidence for gabapentin specifically in fibromyalgia is limited compared to pregabalin:

• Only one adequately powered study (150 participants, 12 weeks) demonstrated efficacy for gabapentin at doses up to 2400 mg daily 4, 5
• In this trial, 49% of gabapentin-treated patients achieved ≥30% pain reduction versus 31% with placebo 4, 5
• 91% reported "better" on patient global impression of change versus 47% with placebo 4, 5
• The Cochrane review concluded there is "very low quality evidence" and "insufficient evidence to support or refute" gabapentin's use due to limited data from a single trial 4

Comparison to Pregabalin

• Pregabalin has substantially more robust evidence with multiple large trials (3283 participants across 5 studies) showing high quality evidence for efficacy 6
• Pregabalin 300-600 mg produces substantial benefit (≥50% pain reduction) in about 9% more patients than placebo (24% vs 14%) with NNT of 7-14 6
• This is why pregabalin is specifically listed as a first-line medication while gabapentin is mentioned only as an alternative 2, 3

Practical Dosing Considerations

• Gabapentin requires careful titration due to nonlinear pharmacokinetics (saturable absorption), starting with low doses and gradually increasing 3
• The studied dose range was 1200-2400 mg daily in divided doses 5
• Both gabapentin and pregabalin require dosage adjustment in patients with renal insufficiency 3

Important Caveats

• 16% of gabapentin-treated patients discontinued due to adverse events versus 9% with placebo 4
• Common adverse events include dizziness, somnolence, weight gain, and peripheral edema 1
• Regular reassessment of pain levels, function, and side effects is essential every 4-8 weeks 3
• If partial pain relief is achieved, consider adding another first-line medication from a different class rather than increasing gabapentin dose 3
• Gabapentin should be part of a comprehensive approach that includes non-pharmacological interventions, not used as monotherapy 3

What to Avoid

• Do not prescribe corticosteroids or strong opioids for fibromyalgia, as they lack efficacy and cause significant harm 2, 3
• Do not rely solely on pharmacological therapy without implementing exercise and behavioral approaches 3