Diarrhea on Wegovy (semaglutide 2.4 mg): Week-by-Week Timeline of What to Expect

What the 2.4 mg trials actually recorded

The diarrhea figure comes from a pooled safety table: three randomized, double-blind, placebo-controlled trials in adults with obesity or overweight, lasting up to 68 weeks, with 2,116 people on Wegovy 2.4 mg injection and 1,261 on placebo [1]. In that table diarrhea appears at 30% versus 16%, any gastrointestinal reaction at 73% versus 47%, and diarrhea as the reason for stopping treatment at 0.7% versus 0.1% [1]. Overall discontinuation for adverse reactions was 6.8% versus 3.2%, with nausea (1.8% vs 0.2%) and vomiting (1.2% vs 0%) named ahead of diarrhea [1].

The dose ladder and the fluid-loss warning

Wegovy starts at 0.25 mg once weekly for 4 weeks, then rises in 4-week steps: 0.5 mg for weeks 5-8, 1 mg for weeks 9-12, 1.7 mg for weeks 13-16, then 2.4 mg from week 17 [1]. Adults who tolerate 2.4 mg for at least 4 weeks and need more weight loss can go to a maximum of 7.2 mg weekly [1].

The label's only timing detail that bears on diarrhea concerns fluid loss. Acute kidney injury from volume depletion occurred at 0.4 versus 0.2 cases per 100 patient-years (7 versus 4 adults), more often in people with prior kidney impairment and during dose titration, often after gastrointestinal fluid loss [1].

A 2025 review of GLP-1 obesity drugs says the main adverse events with these medicines are gastrointestinal, including diarrhea, and that they often can be mitigated by slow up-titration [2]. At the 7.2 mg dose, gastrointestinal reactions led to discontinuation in 3% of people, the same 3% as on 2.4 mg, versus 0.3% on placebo [1].

What the label flags when diarrhea is not mild

Wegovy's warnings include severe gastrointestinal adverse reactions, reported in 4.1% of people on Wegovy injection versus 0.9% on placebo, and the label says Wegovy is not recommended in people with severe gastroparesis [1]. Postmarketing reports in the same label include ileus, intestinal obstruction and severe constipation with fecal impaction [1].

For volume loss, the label says to monitor kidney function in patients reporting reactions that could lead to volume depletion [1]. For the pancreas, the label describes persistent or severe abdominal pain, sometimes radiating to the back, with or without nausea or vomiting, and says to discontinue Wegovy if pancreatitis is suspected [1]. Acute gallbladder disease is a separate warning [1].

Missed doses and restarts

The label's missed-dose rule for the injection is to give the dose if the next scheduled dose is more than 2 days away. After two or more consecutive missed doses, the Wegovy label calls for re-escalation from a lower dose [1].