WEGOVY side effects

Whose numbers these are

Every rate below comes from one place: the trials the WEGOVY label reports in its own adverse-reactions section. Three randomized, double-blind, placebo-controlled trials, 2,116 adults with obesity or overweight on WEGOVY 2.4 mg injection for up to 68 weeks, against 1,261 on placebo. The people in them had a mean age of 48, 71% were women, and 19% had type 2 diabetes.¹

That last detail is the one worth holding on to. A rate is a rate in a population, and this population was recruited for weight trials, so these are not the numbers for someone taking semaglutide for diabetes, and they are not the numbers for any other drug. The label says so itself, in the sentence it puts above every one of its tables:

The stomach reactions, in the label's own numbers

Table 3 of the label lists 19 reactions that turned up in at least 2% of people on WEGOVY and more often than on placebo. These are the ones affecting the gut, with the placebo column beside them, because a number without its comparison is not information:¹

Read the placebo column before you read the other one. Sixteen percent of people who were injecting salt water reported nausea, and 16% of them reported diarrhea; 11% reported constipation. Some of what happens on this drug would have happened anyway, and the honest size of the drug’s own contribution is the gap between the two columns, not the height of the first.

How many people stopped

This is the number that puts the table in proportion. In those trials, 6.8% of people on WEGOVY 2.4 mg and 3.2% of people on placebo permanently stopped treatment because of a side effect. The reactions behind those exits were nausea (1.8% against 0.2% on placebo), vomiting (1.2% against 0%) and diarrhea (0.7% against 0.1%).¹

So: nearly half of people reported nausea, and fewer than two in a hundred left because of it. Both facts are from the same table of the same label, and a page that gives you only one of them is telling you half of what it knows.

At the higher 7.2 mg dosage, studied later in two 72-week trials, 5% of people on 7.2 mg, 5% on 2.4 mg and 2% on placebo stopped because of a side effect, and the label says gastrointestinal reactions were the most common reason in all three arms.¹

What the tablet trial found

WEGOVY tablets were studied in their own trial: 204 adults with obesity or overweight and at least one weight-related condition, on 25 mg tablets for up to 64 weeks. On the common reactions the label is brief, and the brevity is the finding: it says the types and frequency of common adverse reactions in the tablet trial were similar to those in Table 3, the injection’s table above.¹

Where the tablet trial has its own numbers, they are these: 6.9% of people on tablets and 5.9% on placebo stopped because of a side effect, with gastrointestinal reactions behind 3.4% of the tablet exits. Severe gastrointestinal reactions were reported in 2% of people on tablets and 0% on placebo. Gallstones, which the label calls cholelithiasis, were reported by 2.5% on tablets against 1% on placebo tablets.¹

What the tablet costs, and what the label says about taking it on an empty stomach, is on the WEGOVY pill page.

The risks the label handles separately

Common is not the same as serious, and the label keeps them apart. Alongside a boxed warning about the risk of thyroid C-cell tumors, it devotes ten numbered sections to risks that are not in the frequency table at all: acute pancreatitis, acute gallbladder disease, hypoglycemia, acute kidney injury from volume depletion, severe gastrointestinal reactions, hypersensitivity reactions, diabetic retinopathy complications in people with type 2 diabetes, heart rate increase, and pulmonary aspiration during general anesthesia or deep sedation.¹

Those sections are short, specific and written for the person taking the drug as much as for the prescriber, and they are worth reading in the label itself rather than in a summary of it. The Medication Guide that comes with the pen says which symptoms mean calling your prescriber straight away, and the page on how long side effects last quotes those lines in full.

When they turn up, and how long they run

The timing is not in this table, because the table does not carry time. Both labels say these reactions are reported most during dosage escalation, and a pooled analysis of the 2.4 mg trials puts a shape on it: most first episodes in the first 16 weeks, a peak around week 20, and a typical bout of nausea running about 8 days. That page has the week-by-week picture, and the nausea page covers what people try and when to call. Three of the rows in the table above have their own pages: diarrhea, constipation and reflux.

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