Based on NIH | Can gabapentin cause constipation, how common is this side effect, and what can I do to prevent or manage it?

Gabapentin and constipation: what to know

Yes gabapentin can cause constipation in some people. In clinical trials, constipation occurred in about 4% of gabapentin‑treated adults versus about 2% with placebo, suggesting a small but measurable increase over baseline. ^{[1] [2]} Constipation is listed among common gastrointestinal side effects in official patient information, along with dry mouth, nausea, and diarrhea. ^[3]

How common is constipation?

• In pooled randomized trial data summarized in U.S. labeling, constipation occurred in roughly 4% of people taking gabapentin compared with about 2% on placebo. ^{[1] [2]}
• These frequencies are lower than for the most common gabapentin side effects such as dizziness (~21–28%) and sleepiness (~16–21%), but they are still notable for sensitive individuals. ^{[4] [1]}

Quick reference table

Adverse effect (approx.)	Gabapentin (%)	Placebo (%)	Source
Dizziness	21–28	5–8	[4] [1]
Somnolence (sleepiness)	16–21	3–5	[4] [1]
Peripheral edema (swelling)	~8	~2	[4] [1]
Constipation	~4	~2	[1] [2]
Dry mouth	~5	~1	[1] [2]
Diarrhea	~6	~3	[1] [2]

Why might gabapentin cause constipation?

Gabapentin can slow intestinal movement in some people and may also contribute indirectly via sedation and reduced activity, which can slow bowel transit. While most cases are mild, individual responses vary and constipation can be bothersome. ^{[3] [4]}

Practical prevention tips

• Hydration: Aim for adequate daily fluids unless your clinician has restricted fluids for another condition. More fluids help soften stool and support regularity.
• Fiber: Increase dietary fiber gradually (fruits, vegetables, legumes, whole grains) to about 20–35 g/day as tolerated to avoid gas and bloating.
• Activity: Gentle daily movement (walking, stretching) can stimulate bowel motility.
• Routine: Try a regular bathroom schedule, especially after meals when the “gastrocolic reflex” is strongest.
• Review other constipating meds: Opioids, some anticholinergics, iron, and calcium supplements can compound constipation; ask your clinician or pharmacist to review your list.
  These non‑drug measures are widely recommended for medication‑related constipation and are generally safe first steps.

Over‑the‑counter options if needed

If lifestyle steps aren’t enough, consider simple OTC aids; it’s best to discuss with a clinician or pharmacist if you have other conditions or take multiple medicines.

• Osmotic laxatives: Polyethylene glycol (PEG 3350) draws water into the stool and is commonly used for short‑term relief.
• Bulk‑forming fiber: Psyllium can help if you maintain good hydration; start low and increase slowly.
• Stool softeners: Docusate may help if stools are hard, though evidence is modest.
• Stimulant laxatives: Senna or bisacodyl can be used intermittently if other options fail; prolonged daily use is usually avoided without medical advice.
  These options are general best practices for constipation management; they can be paired with gabapentin if your clinician agrees.

When to talk to your clinician

• Persistent constipation (e.g., fewer than three bowel movements per week with straining or hard stools for over a couple of weeks).
• New or worsening abdominal pain, vomiting, blood in stool, or unexplained weight loss.
• If you have kidney disease, significant heart disease, or are pregnant get personalized guidance before using laxatives.
• If constipation started after beginning gabapentin and does not improve with the measures above, your prescriber may consider dose adjustment, slower titration, or alternative therapies. Gabapentin’s side‑effect profile shows constipation is less frequent than dizziness and drowsiness, but dose changes can still help if you are sensitive. ^{[4] [1]}

Key takeaways

• Gabapentin can cause constipation in a minority of users about 4% in trials slightly higher than placebo. ^{[1] [2]}
• Most cases are mild and respond to hydration, fiber, activity, and, if needed, short‑term OTC laxatives. ^[3]
• If symptoms persist or are severe, discuss options with your prescriber, including dose adjustments or alternative treatments; gabapentin’s overall adverse‑event risk is common but usually tolerable. ^[4]

Sources: Official U.S. drug information lists constipation as a known side effect and quantifies its frequency versus placebo; consumer information also lists constipation among common side effects. ^{[1] [2] [3]}