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.
In trial — Ozempic
6.5%
In trial — placebo
2.5%
Severity
mild
Source: SUSTAIN-6 (Marso et al., NEJM 2016)
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.
Side effect
Ozempic nausea
Nausea is the most common GLP-1 side effect. It usually shows up in the first week of a new dose, peaks within…
ReadSide effect
Ozempic diarrhea
Diarrhea affects roughly 15–30% of GLP-1 users, typically in the first 4–8 weeks. It tends to alternate with c…
ReadSide effect
Ozempic vomiting
Vomiting is less common than nausea — about 10–15% of GLP-1 users experience it, usually in the first month of…
ReadSide effect
Ozempic headache
Headaches are reported by 10–15% of GLP-1 users — often a side effect of dehydration and low blood sugar rathe…
Read