Saxenda (liraglutide) side effects

The numbers below are taken from product information and published RCTs. In the trials, side effects were compared with a placebo group that received the same diet and exercise counseling; for this reason each rate is given together with the placebo rate.

What are the most common side effects of Saxenda?

According to the US label, the safety data are based on 3,384 overweight or obese adults who received liraglutide in five double-blind, placebo-controlled trials. The mean age of participants was 47 and 71% were women; mean treatment duration was 46 weeks. ^[1] The main reactions seen more often in the liraglutide group than with placebo:

Source: US Saxenda label, Table 2 (a portion of those occurring at a frequency of 2% and above in adults and more common than with placebo). ^[1] In the trial that included participants with type 2 diabetes who were not using insulin, blood glucose falling below 54 mg/dL was seen in 12.6% with liraglutide and 6.6% with placebo. ^[1]

The Türkiye SmPC gives the same table with frequency categories: nausea, vomiting, diarrhea, constipation, and headache are “very common” (in at least 1 in 10 people); dry mouth, indigestion, gastritis, reflux, bloating, insomnia, taste disturbance, dizziness, and fatigue fall in the “common” group. The SmPC states that insomnia was seen mainly in the first 3 months of treatment. ^[2]

How long does Saxenda nausea last?

According to the Türkiye SmPC, most gastrointestinal events are mild to moderate and transient; in the vast majority, treatment did not need to be stopped. Reactions generally appeared in the first week of treatment and resolved within a few days or weeks while treatment continued. People over 65 and those with mild-to-moderate renal impairment may experience more gastrointestinal effects. ^[2] The US label also states that the proportion of patients reporting nausea decreases as treatment continues and that malaise, fatigue, taste disturbance, and dizziness were reported mostly in the first 12 weeks, often together with nausea and vomiting. ^[1]

The gradual dose escalation in the product information is defined to increase gastrointestinal tolerability. ^[2]

What proportion stop Saxenda because of side effects?

• Adults: 9.8% of the liraglutide group and 4.3% of the placebo group stopped treatment early because of adverse reactions. The most common causes were nausea (2.9% versus 0.2%), vomiting (1.7% versus under 0.1%), and diarrhea (1.4% versus 0%). Discontinuation due to gastrointestinal reactions was 6.2% versus 0.8%. ^[1]
• 160-week trial: Discontinuation due to adverse reactions was 13% with liraglutide and 6% with placebo. ^[1]
• Adolescents (ages 12–17): In the RCT with 251 adolescents, discontinuation of treatment due to adverse events was 10.4% with liraglutide and 0% with placebo. ^[4]

In the SCALE trial, serious adverse events were seen in 6.2% of the liraglutide group and 5.0% of the placebo group; the most commonly reported adverse events were mild-to-moderate nausea and diarrhea. ^[3] In the LEADER trial in people with type 2 diabetes as well, the most common adverse events causing discontinuation of liraglutide were gastrointestinal. ^[7]

What are the serious side effects?

Warnings in the US label and frequencies in the adult trials: ^[1]

• Acute pancreatitis: Pancreatitis confirmed by an adjudication panel was seen in 9 of 3,291 people (0.3%) with liraglutide and in 2 of 1,843 people (0.1%) with placebo. In the postmarketing period, fatal hemorrhagic and necrotizing pancreatitis has also been reported. The symptom is persistent or severe abdominal pain, sometimes radiating to the back; if suspected, the drug is stopped.
• Gallbladder disease: Gallstones 2.2% versus 0.8%, gallbladder inflammation 0.8% versus 0.4%. Most liraglutide users who had these events had their gallbladder removed. The label states that the difference persisted after the amount of weight loss was taken into account.
• Serious gastrointestinal reactions: 4.8% versus 1.4%. The label does not recommend use in people with severe gastroparesis; postmarketing intestinal obstruction (ileus) and severe constipation are also listed.
• Acute kidney injury due to fluid loss: Cases, some requiring dialysis, have been reported postmarketing; most are in patients with fluid loss due to nausea, vomiting, or diarrhea.
• Increase in heart rate: A mean increase of 2–3 beats per minute in resting heart rate was seen. An increase of more than 10 beats at two consecutive visits was 34% with liraglutide and 19% with placebo. If a sustained increase is seen, treatment is stopped according to the label.
• Serious hypersensitivity: There are reports of anaphylaxis and angioedema.
• Aspiration during anesthesia: Because it slows gastric emptying, aspiration into the lungs under general anesthesia or deep sedation has been reported rarely; the label provides for informing the healthcare team about the drug before planned procedures.
• Hypoglycemia: Risk increases when used together with insulin or a sulfonylurea in type 2 diabetes; in the weight management trial in type 2 diabetes, severe hypoglycemia was seen in 0.7% of the liraglutide group and all of these people were using a sulfonylurea.

The Türkiye SmPC lists the same risks and additionally states that in type 2 diabetes trials, thyroid-related events such as goiter were reported, particularly in people with preexisting thyroid disease, and that cutaneous amyloidosis can occur at the injection site. ^[2]

Does Saxenda cause thyroid cancer?

This question does not yet have a definitive answer. According to the US label, liraglutide caused dose- and duration-dependent thyroid C-cell tumors in rats and mice at clinically relevant exposures; whether it causes medullary thyroid carcinoma (MTC) in humans is not known. Postmarketing cases of MTC have been reported, but the data are insufficient to prove or exclude a causal relationship. The value of routine calcitonin measurement or thyroid ultrasound for early diagnosis is uncertain. ^[1] The Türkiye SmPC states that tumors were not seen in monkeys treated for 20 months and that the relevance of the rodent finding to humans is probably low, but cannot be entirely disregarded. ^[2]

In the adult trials, confirmed papillary thyroid cancer was seen in 8 of 3,291 people (0.2%) with liraglutide and none with placebo; 4 of these were smaller than 1 cm and 4 were diagnosed in surgical specimens taken because of findings before treatment. Confirmed breast cancer was seen in 0.7% of women receiving liraglutide and 0.2% of those receiving placebo; the label states that the number of cases is too small to determine a relationship with the drug. ^[1]

Does Saxenda cause suicidal thoughts?

The EMA’s pharmacovigilance committee PRAC completed in April 2024 the review it started in July 2023 on case reports in liraglutide and semaglutide users. Evaluating nonclinical studies, clinical trials, postmarketing data, and electronic health record studies, the committee concluded that the available evidence does not support a causal link between GLP-1 receptor agonists, including liraglutide, and suicidal and self-harm thoughts and behaviors, and stated that no change in product information was needed. Marketing authorization holders will continue to monitor these events. ^[5]

The “suicidal behavior and ideation” warning section in the US Saxenda label was removed in the February 2026 revision. ^[1] In the adolescent trial, one suicide occurred in the liraglutide group, and the investigator judged a relationship with treatment unlikely. ^[4]

Are side effects different in adolescents?

The profile is similar, but some effects are more frequent. In the 56-week adolescent trial in the US label, vomiting was seen in 34.4% with liraglutide and 4.0% with placebo; nausea 42.4% versus 14.3%; reported low blood glucose (below 70 mg/dL) 15.2% versus 4.0%. In adolescents, resting heart rate increased by a mean of 3–7 beats per minute. ^[1] The Türkiye SmPC also states that vomiting was seen 2 times more often in adolescents than in adults and that no effect on growth or pubertal development was detected in 56 weeks of treatment. ^[2] In the adolescent RCT, gastrointestinal adverse events were 64.8% versus 36.5%. ^[4]

What is the situation in pregnancy and breastfeeding?

According to the Türkiye SmPC, liraglutide should not be used in pregnancy; if pregnancy is desired or occurs during treatment, treatment should be stopped. Animal studies have shown reproductive toxicity; the potential risk to humans is not known. Effective contraception is recommended for women of childbearing potential. Because it is not known whether it passes into breast milk, it should not be used during breastfeeding either. ^[2] The US label states that weight loss offers no benefit in pregnancy and may harm the fetus, and that the drug should be stopped when pregnancy is recognized. ^[1]

Risk with counterfeit pens

The UK medicines regulator MHRA reported that among the counterfeit Ozempic and Saxenda pens found in the country were ones containing insulin. When such a pen is used, symptoms of low blood glucose such as dizziness, sweating, and blurred vision, and in severe cases seizures and loss of consciousness, can occur. The MHRA states that products in the legitimate supply chain are not affected. ^[6] Counterfeit warnings in Türkiye are reported in the main guide.

This page is not a substitute for a personal treatment decision; whether a side effect is related to the drug and whether treatment will be continued depends on the physician’s assessment.