Wegovy Side Effects: What to Do About Diarrhoea

Step 1: Recognise what is happening and when it tends to peak

Wegovy slows the rate at which your stomach empties food into the small intestine, that is central to how it reduces appetite. The same mechanism means your gut receives signals it is not used to, especially early in treatment. Loose stools or outright diarrhoea are a predictable result for a significant proportion of people, and the NHS semaglutide medicines page lists them among the most frequently reported side effects alongside nausea and vomiting.

Timing matters. The peak risk tends to fall in the first two to four weeks at any new dose level, which means it can reappear each time your prescriber steps your dose up through the schedule. For many people the pattern is brief: a few uncomfortable days, then things settle. That does not make it trivial (especially if it strikes during a busy work week or you have a holiday booked) but knowing it is likely to pass does change how you manage it.

If you started Wegovy and diarrhoea arrived within the first 48 hours, that is typical. If it began weeks into a stable dose with no dose change, it is worth mentioning at your next clinical review. Our prescribers talk through the side-effect timeline as part of the assessment process, and you can read more about how Wegovy diarrhoea tends to develop and resolve before deciding whether to book a consultation. Our prescribers talk through the side-effect timeline as part of the assessment process; you can explore what a full consultation covers on the Wegovy treatment page.

Step 2: Practical steps that can reduce the severity

There is no single fix, but several straightforward adjustments reduce both the frequency and the impact of diarrhoea on Wegovy.

Hydration is the priority. When diarrhoea is frequent, fluid and electrolyte loss accumulates quickly. Plain water, diluted squash and oral rehydration sachets are all reasonable. Alcohol and heavily caffeinated drinks tend to make things worse.

Diet adjustments help too. Fatty, greasy or very rich foods amplify GI side effects because fat is processed more slowly on Wegovy. Smaller, lower-fat meals taken across the day rather than two or three large ones give the gut less to deal with in one go. The broader picture of semaglutide and diarrhoea (including what dietary patterns seem to trigger it) is covered in more detail separately.

Do not stop Wegovy without speaking to your prescriber first. Many people who stop because of early GI effects would have found them settle within another week or two; abrupt stopping means restarting the titration schedule from scratch. If symptoms are difficult, a prescriber can discuss slowing the titration pace rather than abandoning treatment entirely. For context on how bad diarrhoea can get and what separates manageable from serious, the guide to severe diarrhoea on Wegovy covers that clearly.

Step 3: When to seek medical help, and what warrants it urgently

Most diarrhoea on Wegovy does not need a GP visit. Some does.

Seek prompt medical attention if you have severe diarrhoea that is not improving after a couple of days, if you cannot keep fluids down alongside it, or if you are showing signs of dehydration, marked thirst, very dark urine, dizziness or confusion. Dehydration can impair kidney function, a risk flagged in the Wegovy Summary of Product Characteristics on the eMC.

Call 999 or go to A&E for severe, persistent abdominal pain that spreads to your back, particularly if it arrives with vomiting and does not ease. This symptom pattern can indicate acute pancreatitis, which the MHRA highlighted as a known but uncommon serious risk with GLP-1 medicines in a Drug Safety Update issued in January 2026. Pancreatitis is rare, but the symptoms overlap with severe GI upset, if there is any doubt, get seen.

Blood in your stool, a sudden high fever alongside diarrhoea, or symptoms that worsen rather than improve after four or five days all warrant a call to 111 or your GP rather than waiting. You can also report any suspected side effect (serious or not) through the MHRA Yellow Card scheme, which helps regulators monitor real-world safety signals for medicines like Wegovy.

If you have questions about your own symptoms and are already a patient with us, our aftercare team is available seven days a week. For everything else about what Wegovy's full side-effect profile looks like, the complete Wegovy side effects page covers all the major categories together.

Step 4: What to tell your prescriber and when to loop them in

Your prescriber needs to know if diarrhoea is persistent (beyond two to three weeks at a stable dose), recurring at each dose increase, or severe enough to affect your daily life. That information shapes the decision about whether to slow titration, hold the current dose for longer, or investigate whether something else is going on.

Transfer patients and those requesting a dose increase at nume provide evidence of their current treatment before any step up is approved. That clinical gate exists partly for this reason: moving too fast through the dose schedule without settling is the single most common driver of prolonged GI side effects on injectable semaglutide. Our clinical team's approach to this is set out on the clinical team page.

Diarrhoea that appears well after you have been stable on a dose deserves a fresh look, it could reflect a dietary change, an interaction with another medicine, or something unrelated to Wegovy. A real prescriber, not an automated system, reviews your case. Knowing you have that access makes a material difference to how safely you manage a medicine like this. If you are not yet a patient and want to understand the full process, you can read about how diarrhoea after starting Wegovy is typically monitored, or go straight to a consultation through the treatment page.