Victoza® and blood clots

What the product information says

Neither the US label nor the European summary lists deep vein thrombosis, pulmonary embolism or any other blood clot as a Victoza® reaction, in trials or in postmarketing reports. ^[1][2] The Canadian monograph lists pulmonary embolism under “less common clinical trial adverse reactions”, a list that also includes heart, brain and cancer events, with no rate and no statement that the drug caused it. ^[3]

The LEADER trial, which supports Victoza®’s US approval for lowering cardiovascular risk in type 2 diabetes with heart disease, followed thousands of people for years, but the labels do not report clot outcomes from it. ^[1]

What the larger analyses found

Trial meta-analyses. A 2025 analysis of 39 randomized trials with 70,499 people found a non-significant trend towards more venous clots on GLP-1 medicines, a significant rise in deep vein thrombosis, especially in trials longer than 18 months and in cardiovascular outcome trials, the design LEADER used, and no link with pulmonary embolism. ^[5] Another 2025 analysis, limited to 27 placebo-controlled trials with 84,003 people, found no significant difference in venous clots overall and a lower risk of pulmonary embolism. ^[6] Neither abstract reports liraglutide separately. ^[5][6]

Real-world data in diabetes. A 2026 meta-analysis of six studies in adults with diabetes found GLP-1 medicines linked with a lower risk of venous clots than DPP-4 inhibitors, another common diabetes drug class; the authors called the evidence limited. ^[7]

Reporting data. A 2026 analysis of US FDA reports found that GLP-1 medicines as a group were reported for clots less often than other drugs, less often than orlistat for venous clots and less often than SGLT-2 inhibitors overall; within the class, liraglutide had higher reporting ratios than the others. ^[4] Such reports reflect what is sent in, so they cannot give risk or prove cause. ^[4]

A liraglutide trial that measured clotting

One randomized trial looked directly at clotting markers with liraglutide at the Victoza® dose. In 72 women with polycystic ovary syndrome, a condition linked with a higher clot risk, liraglutide 1.8 mg a day for 26 weeks caused about 5% weight loss; thrombin generation changed within the liraglutide group but not differently from placebo, and there was a trend towards better clot breakdown. ^[8] The authors read this as a possible reduction in clotting tendency that needs larger studies. ^[8] It measured blood tests, not actual clots.

If you already take a blood thinner

This is the Victoza®-specific point. Europe states that no interaction study with warfarin has been done and that, for medicines with a narrow safe range such as warfarin, a relevant interaction cannot be excluded; it recommends more frequent INR monitoring after starting liraglutide in people on warfarin or other coumarin medicines. ^[2] The EU leaflet tells patients that more frequent blood tests may be needed, and Canada includes a similar caution. ^[2][3] The US label does not mention warfarin specifically but asks for caution with oral medicines because of the slower stomach emptying. ^[1]

Vomiting and diarrhoea, the most common early Victoza® effects, can also affect how oral medicines are absorbed; Europe notes this for severe diarrhoea. ^[2]

Everyday risk factors

CDC lists the main risk factors for deep vein thrombosis and pulmonary embolism: injury to a vein from fractures or major surgery; slow blood flow from bed rest, a leg cast or long periods of sitting; higher oestrogen from contraceptives, hormone therapy or pregnancy; heart disease, lung disease, cancer and inflammatory bowel disease; a previous clot, an inherited clotting disorder or family history; older age; and overweight or obesity. ^[10] The risk grows when several factors are present at once. ^[10]

Several of these are common in people prescribed Victoza®, such as heart disease and excess weight. Dehydration is not on the CDC list, but it is a known Victoza® risk in its own right because of its link with kidney injury. ^[1][10]

What the sources describe

• Move around as soon as you can after surgery, illness or bed rest. ^[9]
• On journeys longer than 4 hours, get up and walk every 1 to 2 hours, wear loose clothing and exercise your calves while seated. ^[9]
• If you are at higher risk, ask your doctor about compression stockings or anticoagulant medicine, as CDC suggests. ^[9]
• If you take warfarin, tell the clinic monitoring your INR when Victoza® is started or changed. ^[2]
• Tell your surgical team you use Victoza® before any planned operation, as the US label asks. ^[1]

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

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