Gabapentin Can Cause Dry Mouth
Yes, gabapentin can cause dry mouth, though it occurs less frequently than other common side effects like dizziness and somnolence. According to FDA-approved labeling, dry mouth occurred in 5% of patients with postherpetic neuralgia treated with gabapentin compared to 1% with placebo, and in 2% of epilepsy patients compared to 1% with placebo 1.
Frequency and Clinical Significance
Dry mouth (xerostomia) is a documented but relatively uncommon adverse effect of gabapentin therapy. The FDA drug label clearly lists dry mouth as occurring in:
- 5% of postherpetic neuralgia patients (versus 1% placebo) 1
- 2% of epilepsy patients over 12 years (versus 1% placebo) 1
This places dry mouth well below the most common gabapentin side effects—dizziness (28%), somnolence (21%), and peripheral edema (8%) in postherpetic neuralgia trials 1.
Comparison with Related Medications
Pregabalin, a closely related gabapentinoid, causes dry mouth at similar rates. Clinical guidelines note that both gabapentin and pregabalin share nearly identical adverse effect profiles, with dry mouth listed among common side effects alongside dizziness, somnolence, and constipation 2, 3. When gabapentin is combined with morphine for neuropathic pain, the frequency of dry mouth increases significantly compared to gabapentin alone 4.
Clinical Context and Management
While dry mouth from gabapentin is generally mild and dose-dependent, it differs fundamentally from the severe xerostomia caused by tricyclic antidepressants. Nortriptyline and other tricyclic antidepressants produce prominent anticholinergic effects including severe dry mouth, whereas gabapentin's mechanism (binding to α2δ-1 subunits of voltage-gated calcium channels) does not involve anticholinergic pathways 5, 6.
The incidence of dry mouth may increase with:
- Higher gabapentin doses (up to 3600 mg/day) 7
- Combination therapy with opioids or other medications 4
- Elderly patients, who experience slightly higher rates of adverse effects overall 1
Important clinical considerations:
- Dry mouth from gabapentin is typically manageable and rarely leads to treatment discontinuation 1
- Unlike severe sicca syndrome from immunotherapy, gabapentin-related dry mouth does not typically require systemic treatment with steroids or sialagogues 2
- Simple measures like increased hydration, saliva substitutes, and sugarless gum are usually sufficient 2