Diarrhoea After Wegovy: What to Expect and When to Seek Help

Step 1, Understand why it happens in the first place

Wegovy contains semaglutide, a GLP-1 receptor agonist that slows the rate at which the stomach empties food into the small intestine. That deliberate slowing is central to how the medicine reduces appetite, but it also changes the rhythm of the whole digestive tract. Some people find the gut responds by speeding up in other ways, producing loose stools or urgency. The NHS semaglutide medicines page lists diarrhoea among the common side effects, alongside nausea, vomiting, constipation and indigestion.

Dose increases are the most reliable trigger. The standard escalation starts at 0.25 mg and climbs through several steps to a maintenance dose, with each step giving the digestive system a fresh signal to adapt. Bowel changes at each new level are not a sign that something has gone wrong, they are often the body's first response to an altered gut-hormone pattern. The pattern tends to repeat more mildly as you go higher, because the gut has already done most of its adapting. For a broader look at the full range of gastrointestinal effects linked to the injection, the Wegovy side effects overview covers the picture in more detail.

Step 2, Practical things that genuinely help day to day

Hydration is the first priority. Loose stools lose fluid fast, and even moderate dehydration makes nausea worse and energy lower, a particularly unhelpful combination when you are already adjusting to the medicine. Plain water, diluted squash and oral rehydration sachets all work; large quantities of caffeine or alcohol do not help and may irritate an already-unsettled gut.

Meal choices matter too. Smaller portions eaten more slowly reduce the volume hitting an already-altered digestive system in one go. High-fat and very spicy foods are more likely to provoke urgency, particularly in the first few weeks. Some people find that timing meals further from the injection day helps, though this varies. If you want more granular guidance on food-related triggers, what tends to make diarrhoea worse after eating on Wegovy goes into the specifics. Over-the-counter loperamide is used by some people for occasional relief, but discuss this with a pharmacist or prescriber before using it regularly alongside semaglutide.

Give things a little time. A prescriber or pharmacist is the right person to talk to if loose stools are significantly affecting your daily life, they can consider whether a slower titration, a brief dose pause, or further assessment would help. That conversation is exactly what the clinical review at nume's consultation is designed for.

Step 3, Spot the signs that need prompt medical attention

Most diarrhoea on Wegovy resolves without intervention, but certain patterns warrant a call to your GP, prescriber or 111 promptly. Contact a clinician the same day if you notice any of the following: diarrhoea lasting more than five or six days without improvement; signs of dehydration (dark or very infrequent urination, rapid heartbeat, confusion or pronounced dizziness); blood in your stool; or fever alongside gut symptoms.

Severe, persistent stomach pain that radiates towards the back (with or without vomiting) needs urgent assessment, because acute pancreatitis is a known, if infrequent, serious risk with GLP-1 medicines. The MHRA highlighted this in its January 2026 Drug Safety Update covering the class, and the advice is clear: do not wait and see with that specific symptom pattern. If any of these warning signs appear, stop the injection until you have spoken to a clinician. You can find guidance on the broader spectrum of effects in the Wegovy diarrhoea topic page, including what different durations and presentations can mean.

When diarrhoea appears later in treatment

Most people who reach their maintenance dose find the initial GI disruption has largely passed. If loose stools return after months of settled digestion, the cause is worth investigating rather than attributing automatically to Wegovy. New dietary changes, concurrent medication, illness or a dose increase following a break can all restart gut symptoms. The experience of diarrhoea after six months on Wegovy is a different clinical picture from early-treatment effects and is covered separately. Similarly, if you have recently stopped the injection, bowel changes after stopping Wegovy explains what tends to happen as semaglutide clears the body. Our prescribers discuss side-effect history and current symptoms as part of every clinical review, treatment decisions are always made on the full picture, not a checklist. You can read more about how Wegovy works and who it suits on the Wegovy overview.