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Victoza® and constipation

Victoza constipation: 5% on both doses against 1% on placebo, up to 11.4% in one trial, the rare bowel blockage reports and when to get help.

Published · Updated · Victoza®: side effects by symptom · Written by the PepLabo editorial team

When to get help
Context and scope

Constipation is one of the six most common side effects listed for Victoza®, the once-daily liraglutide injection for type 2 diabetes. It is usually a nuisance rather than a danger, but the label also carries rare reports of bowel blockage after approval. This page brings together the US, European and Canadian product information, what studies of liraglutide and the wider GLP-1 class show, the many other reasons people with diabetes become constipated, and when to get help.

Key takeaways 5
  • In the US pool, constipation was reported by 5% on both Victoza® doses and by 1% on placebo. [1]
  • Canadian trial figures on Victoza® range from 2.1% to 11.4%; the highest came from the 52-week trial using Victoza® alone. [3]
  • The US postmarketing list includes ileus, intestinal obstruction and severe constipation including faecal impaction; the EU rates bowel obstruction as rare. [1][2]
  • A 2025 meta-analysis found no overall rise in bowel obstruction or ileus with GLP-1 medicines, but a higher risk in the liraglutide subgroup, mostly from observational data. [4]
  • NIDDK names diabetes itself, several common heart and blood pressure medicines and low fluid or fibre intake among causes of constipation. [5]

A small number with a large ratio

In Table 1 of the US prescribing information, constipation is the last digestive row: 5% on both doses against 1% on placebo, across five glycemic control trials in adults. [1] The absolute numbers are small, but five times the placebo rate is a clear difference. Unlike nausea or vomiting, the US pool shows no extra step between 1.2 mg and 1.8 mg.

Constipation in the Victoza® adult placebo-controlled pool (US label, section 6.1, Table 1)
GroupPeople in groupReported constipation
Placebo6611%
Liraglutide 1.2 mg6455%
Liraglutide 1.8 mg1,0245%

What other trials recorded

The Canadian monograph shows constipation trial by trial, counted regardless of what investigators thought caused it. [3] The spread is wide. In LEAD-2 the middle dose had the highest rate, in LEAD-3 the top dose did, and in LEAD-5 nobody on placebo reported it. [3] The European summary places constipation in its common class, between 1 in 100 and 1 in 10 people. [2]

Constipation in individual Victoza® trials (Health Canada monograph, section 8.2; EU SmPC section 4.8)
Trial and backgroundVictoza®Comparison
LEAD-2, 26 weeks, with metformin [3]0.6 mg 2.1%; 1.2 mg 4.6%; 1.8 mg 2.5%Placebo 1.7%; glimepiride 1.7%
LEAD-5, 26 weeks, with metformin and glimepiride [3]1.8 mg 2.2%Placebo 0.0%; insulin glargine 0.9%
Trial 1860, 26 weeks, with metformin [3]1.2 mg 4.5%; 1.8 mg 5.0%Sitagliptin 2.7%
Trial 1842, 52 weeks, 1.8 mg with metformin [3]2.5%; 3.1% with insulin detemir addedNo placebo arm
LEAD-3, 52 weeks, Victoza® alone [3]1.2 mg 8.4%; 1.8 mg 11.4%Glimepiride 4.8%
EU frequency class [2]Common (1 in 100 to 1 in 10)—

The rare serious end

Section 6.2 of the US label lists reports received after approval, which cannot give a rate or prove cause: ileus, intestinal obstruction and severe constipation including faecal impaction are among them. [1] Canada says delayed gastric emptying, intestinal obstruction and ileus have been reported in its postmarketing database. [3] The European table rates intestinal obstruction as rare, between 1 in 10,000 and 1 in 1,000 people, and its leaflet describes it as a severe form of constipation with stomach ache, bloating and vomiting. [2]

Research points in two directions. A 2025 systematic review that pooled six studies with over half a million people found no significant overall increase in bowel obstruction or ileus with GLP-1 medicines, with very high variation between studies, but the liraglutide subgroup showed about three times the odds. [4] That analysis mixed trials with cohort and case-control studies, which can show association but not cause. A separate 2025 meta-analysis of 55 placebo-controlled randomised trials found that GLP-1 medicines probably have little or no effect on intestinal obstruction and similar events. [8]

Why it might happen

Label-supported: Victoza® slows stomach emptying as part of its effect on blood sugar after meals. [1] The labels do not describe a separate effect on the large bowel, so this explains slower digestion in general rather than constipation specifically.

Plausible but not measured: decreased appetite affected 10% of people on 1.2 mg and 9% on 1.8 mg in the US pool. [1] NIDDK lists not eating enough fibre and not drinking enough liquids among causes of constipation. [5] Eating and drinking less on Victoza® could therefore contribute, but none of the sources measured that link.

Reported in research: the liraglutide signal for obstruction and ileus comes largely from observational data and has not been confirmed by randomised trials. [4][8]

Other reasons for constipation in diabetes

NIDDK lists a long set of causes, several of them common in people with type 2 diabetes. Conditions that affect metabolism, such as diabetes, and hormone conditions, such as an underactive thyroid, are on it. [5] So are medicines and supplements: calcium channel blockers and diuretics for blood pressure, iron supplements, antacids containing aluminium or calcium, opioid pain medicines and some antidepressants. [5] Changes in routine, travel, ignoring the urge to go, low physical activity and irritable bowel syndrome complete the list. [5]

What the sources describe

  • Movement and fluids: MedlinePlus suggests regular exercise and drinking more water. [6] The Victoza® Medication Guide also asks you to drink fluids to lower the risk of dehydration. [1]
  • Fibre, slowly: MedlinePlus advises adding fibre-rich foods gradually because more fibre can cause gas and bloating, and drinking plenty of water when you do. [6]
  • Routine: going when you feel the urge, trying the same time each day and not skipping meals. [6]
  • Laxatives with care: MedlinePlus says not to take a laxative if you have severe stomach pain, nausea or vomiting, and to check with your provider before using one for more than a week; children should not be given laxatives or enemas without asking their provider. [6][7]
  • Your medicine list: since many medicines contribute, a pharmacist can check what else you take. [5]

Victoza® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk A/S.

When to get help

The signs and contact information below come from this article’s sourced guidance.

Emergency

  • Constant belly pain with constipation, swelling, vomiting or being unable to pass wind

    Contact: Urgent medical care

    NIDDK [5]; EU leaflet [2]

  • Severe stomach pain that does not go away, possibly reaching the back

    Contact: Stop Victoza® and call your provider straight away

    Medication Guide [1]

Today

  • Bleeding from the rectum or blood in the stool

    Contact: See a doctor right away

    NIDDK [5]

  • Constipation with fever, lower back pain or weight loss you were not trying for

    Contact: See a doctor right away

    NIDDK [5]

  • No bowel movement for 3 days, or bloating and stomach pain

    Contact: Contact your provider

    MedlinePlus [6]

At your next appointment

  • Constipation that keeps coming back on Victoza® despite self-care

    Contact: Raise it with your prescriber

    Medication Guide [1]; NIDDK [5]

Questions

How common is constipation on Victoza®?

In the US adult pool, 5% on 1.2 mg and 5% on 1.8 mg, against 1% on placebo. [1] Canadian trials ranged from 2.1% to 11.4% on Victoza®. [3]

Does the higher Victoza® dose cause more constipation?

Not in the US pool, where both doses showed 5%. [1] In the 52-week LEAD-3 trial, though, 1.8 mg reached 11.4% against 8.4% on 1.2 mg. [3]

Has serious bowel blockage been reported with Victoza®?

Yes, rarely. The US label lists ileus, intestinal obstruction and faecal impaction among postmarketing reports, and the EU rates obstruction as rare. [1][2] Research is mixed: one meta-analysis saw a higher risk with liraglutide, another found little or no effect across randomised trials. [4][8]

Can I use a laxative while on Victoza®?

MedlinePlus says to avoid laxatives if you have severe stomach pain, nausea or vomiting, and to talk to your provider before using one for more than a week. [6] A pharmacist can suggest an option that fits your other medicines.

Could my diabetes or my blood pressure tablets be the cause?

They could contribute. NIDDK lists diabetes, calcium channel blockers and diuretics among causes of constipation. [5] Your prescriber can look at the whole picture.

My 12-year-old on Victoza® is constipated. Can we give a laxative?

MedlinePlus advises not giving laxatives or enemas to children without first asking their provider. [7] Tell the prescriber about the constipation, and get help quickly if there is vomiting or severe pain. [5]

Sources

Sources checked on

  1. VICTOZA® (liraglutide) injection Prescribing Information and Medication Guide, Novo Nordisk Revised 10/2025; Medication Guide 05/2025. Sections 5.6, 6.1 (Table 1), 6.2 and 12.2.
  2. Victoza: EPAR – Product Information (SmPC and package leaflet), European Medicines Agency SmPC section 4.8 (Table 1 read from the PDF page image); package leaflet section 4.
  3. VICTOZA® (liraglutide injection) Product Monograph, Novo Nordisk Canada Inc. (Health Canada Drug Product Database) Date of authorization 2025-08-21. Sections 7, 8.2 (Tables 1–4 read from the PDF page images) and 8.5; patient medication information.
  4. Alfehaid L et al. Evaluating bowel obstruction and ileus events in patients on GLP-1 receptor agonists: a systematic review and meta-analysis. Expert Opin Drug Saf 2026 (online 2025) Systematic review including trials, cohort and case-control studies; PubMed abstract.
  5. Symptoms & Causes of Constipation, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
  6. Constipation – self-care, MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine)
  7. Constipation in infants and children, MedlinePlus Medical Encyclopedia
  8. Chiang CH et al. Glucagon-like peptide-1 receptor agonists and gastrointestinal adverse events: a systematic review and meta-analysis. Gastroenterology 2025 Meta-analysis of 55 placebo-controlled randomised trials; PubMed abstract.

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