Why does Wegovy cause shaking — and should you be worried?

Why might Wegovy make you shake?

Semaglutide works partly by slowing the rate at which your stomach empties and by curbing appetite at the brain level. Both effects are intentional (they're what drives weight loss) but they can also mean your body receives glucose more slowly, or simply less of it, if you're eating significantly less than before. That modest dip in circulating blood sugar is enough to trigger the body's stress response in some people: a surge of adrenaline that produces shakiness, sweating and a fluttering heartbeat.

This tends to happen most at the beginning of treatment or in the days after a dose step up, when the appetite-suppressing effect feels sharpest. People who skip meals, cut carbohydrates heavily or exercise strenuously without eating enough are at higher risk. It is not the same as the severe hypoglycaemia seen in insulin-treated diabetes, but the sensation can feel similar and is worth taking seriously.

Less commonly, shaking has nothing to do with blood sugar at all. Fatigue, anxiety about injecting, dehydration from GI side effects such as nausea or vomiting, and even caffeine on an empty stomach can produce mild tremor. The NHS patient information on semaglutide lists the recognised side-effect profile in full; shaking is not listed as a direct pharmacological effect, which is a useful reminder that the cause often lies in what surrounds the medicine rather than the molecule itself. If you are unsure what's driving it, your prescriber is the right first call. You can find more context on living with this treatment day to day on our taking Wegovy guidance page.

Does the timing of your injection change the picture?

The when of your injection matters more than many people expect. Wegovy is a once-weekly injection, so you have flexibility, but some timings set you up for shakiness more than others. Taking your dose late on a Friday evening before a busy weekend of disrupted meals, or on a Monday morning during a hectic week when lunch gets skipped, can mean the first few days of increased appetite suppression coincide with irregular eating. The first few days after an injection tend to carry the strongest appetite-dampening effect for some people, so those days call for a little more deliberate attention to eating regularly, even when hunger signals are quiet.

Some people find that injecting at night suits them because any nausea or fatigue stays in the background while they sleep through the worst of it. Whether that also reduces shakiness depends on whether the cause is GI-related tiredness or a blood-sugar dip, the latter isn't really time-of-day dependent. If you notice shaking consistently at a particular point in your weekly cycle, note it down and share the pattern with your prescriber; that information is genuinely useful for working out whether a timing change would help. The guide to starting Wegovy covers early-week strategies worth reading alongside this.

When is shaking after Wegovy a reason to get medical help?

Mild, brief shakiness that settles after eating something small (a few crackers, a glass of milk, a piece of fruit) is generally a sign that your blood sugar dropped temporarily and recovered. Eating something within a few minutes and feeling normal within 20 minutes or so is the reassuring pattern.

Act promptly if the shaking is severe, gets worse rather than better, or is accompanied by confusion, slurred speech, difficulty concentrating, a very rapid or irregular heartbeat, or loss of consciousness. These signs suggest a more significant blood-sugar event or a different cause entirely, and they need same-day assessment. Call 111, contact your GP, or go to A&E if you cannot be seen quickly elsewhere.

Also seek prompt advice if shaking follows vomiting or diarrhoea that has gone on for more than a day, because dehydration compounds the risk of low blood pressure and electrolyte shifts. The MHRA's Yellow Card scheme is the right place to report any side effect you think is linked to Wegovy, whether or not it resolves, that data helps regulators monitor safety across the whole population using the medicine. Our Wegovy information page covers the broader side-effect landscape if you want the fuller picture. A note on cost: if you're comparing providers and wondering whether price should factor into your choice, our cost context page explains what to look for beyond the headline number.

What practical steps can reduce the chance of shaking?

The single most useful adjustment most people can make is protecting meal regularity. When Wegovy is working well, hunger cues become quieter (which is the point) but that same quietness can mean you reach mid-afternoon without having eaten, and by that stage a blood-sugar dip is already under way. Setting a gentle reminder to eat something, even a small protein-rich snack, can interrupt that chain before it starts.

Staying hydrated matters too. Nausea is common in the early weeks of treatment, and if it's putting you off drinking enough fluids, the resulting dehydration can worsen any shakiness you experience. Small, frequent sips tend to work better than large glasses when nausea is present. Reducing alcohol and heavily sugary drinks also helps stabilise blood sugar across the day.

If you are also taking medicines that affect blood glucose (metformin, sulphonylureas, insulin) let your prescriber know about any shaking episodes. The interaction landscape is one your clinical team should monitor directly. Semaglutide's effects on blood sugar regulation are part of why it's also studied in cardiovascular contexts, as the taking Wegovy for weight loss page explains in more detail. And if you'd like to speak with a prescriber about whether Wegovy is appropriate for your situation, our team at weight-loss treatments can review your case, no waiting list, clinical review the same day your consultation is submitted.