Can Wegovy Cause Blood Clots? What the Evidence Says

Does the clinical trial evidence show a link between Wegovy and blood clots?

Looking at the published data, there is no convincing signal. The STEP 1 trial (a 68-week study involving over 1,900 adults, published in the New England Journal of Medicine) tracked adverse events thoroughly. Venous thromboembolism, the category that covers deep vein thrombosis and pulmonary embolism, was not identified as a notable risk in participants taking semaglutide 2.4mg compared with placebo.

Cardiovascular safety has been scrutinised closely in the semaglutide programme more broadly. The SELECT trial, which examined cardiovascular outcomes in adults with obesity and established heart disease, found that semaglutide actually reduced the risk of major cardiovascular events. That does not mean every circulatory risk is zero, but it does push against the idea that the medicine promotes clotting events in general.

If you are trying to piece together where a claim about Wegovy and blood clots originated, it often traces back to two things: early social media concern, and the entirely reasonable confusion between the background risk of clots in people living with obesity and any risk introduced by the medicine itself. Those are quite different questions.

Why does obesity itself raise clot risk, and does treatment change that?

People with obesity carry a higher background risk of deep vein thrombosis and pulmonary embolism than the general population. Several mechanisms are involved: altered coagulation factor activity, reduced mobility, chronic low-grade inflammation and changes in venous blood flow. This matters when reading any signal from a weight-management trial, because participants already start at above-average clot risk before the first dose.

Weight loss, by contrast, generally improves this risk profile over time. Reduced adipose tissue lowers inflammatory markers, and improved mobility helps circulation. Whether semaglutide contributes to this benefit beyond the weight loss itself is still being studied, but there is no current evidence that the medicine counters the benefit or tips the balance toward harm. The NHS medicines page for semaglutide lists the recognised side effects in plain language; blood clots do not appear among them.

It is worth being clear about a different category of symptom: circulation-related complaints some people notice on Wegovy (such as leg heaviness or bruising at the injection site) are separate from venous thromboembolism and should not be conflated with it. If you are unsure what a symptom means, your prescriber is the right first call.

Which symptoms should prompt urgent care while on semaglutide?

Even without a recognised causal link, the practical rule is straightforward. Symptoms that could indicate a blood clot in anyone (on any medicine or none) should be treated as emergencies.

Call 999 or go to A&E immediately if you develop sudden shortness of breath, chest pain, pain when breathing, coughing blood, or a fast or irregular heartbeat. A swollen, red or painful calf that is warm to the touch also needs same-day assessment. Do not wait to see whether it settles. These symptoms could reflect a pulmonary embolism or deep vein thrombosis, neither of which is safe to monitor from home.

Separately, Wegovy does carry well-established gastrointestinal side effects — nausea, loose stools and indigestion are the most common. Our page on Wegovy and digestive symptoms covers those in detail. Pancreatitis is a rarer but serious concern: the MHRA issued a Drug Safety Update in January 2026 highlighting acute pancreatitis as an infrequent but recognised risk with GLP-1 medicines, flagged by severe stomach pain that may radiate toward the back. Report any suspected serious side effects through the MHRA Yellow Card scheme.

If you are looking at other potential effects of semaglutide, there are questions about blood in stool while on semaglutide, and about blood in urine while using Wegovy, which are addressed separately. These are distinct concerns from clotting and should not be conflated.

Should a history of clots affect whether Wegovy is suitable for you?

A personal or family history of blood clots is exactly the kind of detail that shapes a prescriber's decision. It does not automatically rule Wegovy out, but it changes what questions need answering first. Are you on anticoagulation therapy? Do you have an underlying clotting disorder such as Factor V Leiden or antiphospholipid syndrome? How recent was the event? A prescriber who does not know these things cannot assess you properly.

This is precisely why the Wegovy treatment process involves a genuine clinical consultation rather than a checkbox form. At nume, a GPhC-registered prescriber reads every consultation personally on the day it is submitted, no automation, no overnight queue. If your history includes clotting events, that information is central to their assessment.

You can read more about how semaglutide fits into the wider picture of weight-loss treatment options, or look at the cost of Wegovy in the UK if you are at the planning stage. If you are also thinking about practical storage questions, our guide on the Wegovy expiration date explains what you need to know about keeping your pens safe to use. When you are ready, check your eligibility with our prescribers, there is no charge for the consultation, and there is no obligation.