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Ozempic side effect

Ozempic Constipation: causes, relief, and when to call a doctor

Constipation is reported by 15–25% of patients on GLP-1s. Slowed gastric emptying plus reduced food intake means less bulk reaching the colon — so stools become harder and less frequent.

Reviewed by Jane Novak, MD, MPHLast reviewed 2026-06-22Source: FDA Wegovy Prescribing Information §6.1 ↗ (opens in a new tab)

In trial — Ozempic

23.4%

In trial — placebo

9.5%

Severity

mild

Source: STEP-1 (Wilding et al., NEJM 2021)

Why constipation happens on Ozempic

GLP-1 drugs slow gastric emptying and colonic transit time. Combined with smaller portions, lower fluid intake, and a reduced fiber load, you get harder, less frequent stools.

Timeline

Often persists longer than nausea — many patients deal with it intermittently across the full titration period. Stabilizes with intentional hydration + fiber after 6–12 weeks.

How to manage it at home

  • Increase fiber to 25–35 g/day from whole foods first (chia, ground flaxseed, oats, berries, leafy greens).
  • Drink at least 2L of water daily — fiber without water makes constipation worse.
  • Walk 20–30 minutes most days — gentle movement promotes bowel motility.
  • Magnesium citrate (200–400 mg in the evening) is the most-recommended OTC option.
  • Stool softeners (docusate) for occasional flare; avoid daily stimulant laxatives.
  • Don't skip meals — even small frequent meals trigger the gastrocolic reflex.

Call your prescriber if:

  • No bowel movement for more than 5 days.
  • Severe abdominal pain, distension, or vomiting (possible obstruction or ileus).
  • Blood in stool.

Frequently asked

Does magnesium help with GLP-1 constipation?

Magnesium citrate (200–400 mg in the evening) is the most-recommended OTC option and is well-tolerated with GLP-1 medications. Magnesium oxide is cheaper but less effective. Talk to your prescriber if you have kidney disease before starting.

How much fiber should I eat on a GLP-1?

25–35 g/day, ramped up gradually (sudden increases worsen bloating). Whole-food sources beat supplements: chia seeds, ground flaxseed, berries, oats, beans, leafy greens.

This is general drug information, not medical advice. Talk to a licensed clinician before changing your dose, stopping, or starting any over-the-counter remedy.

Other Ozempic side effects

Drug-specific guides for the other commonly reported reactions on Ozempic.