Saxenda® (liraglutide) and diarrhea

Diarrhea in the product information

All three regulators list diarrhea for Saxenda®, and the EU summary places it in its very common group with nausea, vomiting and constipation. ^[1][2][3] The US and Canadian adult numbers come from the same five placebo-controlled trials of 32 to 56 weeks; the teenage figures come from one 56-week trial. ^[1][3]

Putting the figures in context

One in ten people on placebo also reported diarrhea, which shows how often it happens for ordinary reasons. The extra on Saxenda® is about eleven people in every hundred in adults and eight in teens. ^[1] Among teenagers the placebo rate was unusually high, at 14.3%, so the gap there is narrower than in adults. ^[1]

The label groups diarrhea with the other digestive effects that were mostly mild or moderate and rarely led people to stop. ^[1] The EU summary adds that these reactions usually came in the first weeks and faded within a few days or weeks of continued treatment, and that people aged 65 or over, or with mild to moderate kidney impairment, may have more of them. ^[2]

One less obvious finding sits further down the US tables: gastroenteritis was reported more often on Saxenda® than placebo, at 4.7% against 3.2% in adults and 12.8% against 4.8% in teens, and viral gastroenteritis at 2.8% against 1.6% in adults. ^[1] The label does not explain this, but it is a reminder that a stomach bug and a drug effect can be hard to tell apart.

What the trials add

In SCALE Obesity and Prediabetes, the largest Saxenda® trial, nausea and diarrhea were the adverse events reported most often with liraglutide 3 mg, and they were mostly mild or moderate. ^[4] In the adolescent trial, 64.8% of teens on liraglutide had some digestive adverse event, against 36.5% on placebo. ^[5]

Neither the product information nor these trial reports explains why liraglutide loosens stools in some people while it constipates others; both effects appear in the same adult table at similar rates. ^[1] What the label does establish is that the medicine acts on the gut, slowing stomach emptying, and on appetite. ^[1]

Why fluid loss matters on Saxenda®

Section 5.6 of the US label describes post-approval reports of sudden kidney injury among liraglutide users, some of whom needed dialysis. Most happened in people who had become dehydrated from nausea, vomiting or diarrhea, and the label asks for kidney function to be checked in people with such reactions, especially while the dose is being increased. ^[1] The Canadian monograph adds that people with moderate kidney impairment may have more digestive side effects and fatigue. ^[3]

MedlinePlus lists the early signs of dehydration as thirst, a dry mouth, passing little urine, darker urine, headache and muscle cramps, and the severe signs as very dark or no urine, confusion, dizziness and a fast heartbeat. ^[8] Little or no urine is also one of the warning signs of acute kidney failure. ^[9]

There is a second, quieter effect. The EU summary notes that diarrhea may affect the absorption of other medicines taken by mouth, and the US label asks for monitoring of oral medicines because liraglutide slows the stomach. ^[1][2] If you rely on tablets with a narrow margin, such as warfarin, or on an oral contraceptive, ask your pharmacist what a bout of diarrhea means for them.

Other common reasons for loose stools

• Infections from contaminated food or water, or viruses such as norovirus. ^[6]
• Other medicines: antibiotics, some cancer treatments and antacids containing magnesium. ^[6]
• Food intolerances such as lactose intolerance, and bowel conditions such as irritable bowel syndrome or Crohn’s disease. ^[6]
• Travel to areas with unsafe food or water. ^[6]
• MedlinePlus treats diarrhea lasting four weeks or more as chronic and a possible sign of an underlying disease, whatever medicine you take. ^[6]

What helps while it lasts

MedlinePlus self-care for diarrhea focuses on replacing fluid: drink clear fluids through the day, with water as the first choice, and take extra liquid after each loose stool. It also suggests small meals instead of large ones, some salty foods, and foods rich in potassium such as bananas and potatoes, unless you have significant kidney disease. ^[7]

Gentle choices include baked or grilled lean meat, cooked eggs, white rice, pasta and cooked vegetables without skins or seeds. Fried and greasy foods, gas-forming vegetables, caffeine, alcohol and fizzy drinks are best avoided, and dairy can be cut back if it seems to make things worse. ^[7]

MedlinePlus mentions that a provider may suggest a medicine to slow diarrhea or a fibre supplement. ^[7] Check with your pharmacist or prescriber before using either with Saxenda®. The Medication Guide asks you to drink fluids to reduce the chance of dehydration and to tell your provider straight away about diarrhea that does not go away. ^[1]

Saxenda® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.

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