Short answer: In the label's placebo-controlled trials in adults, nausea was the most common side effect of Victoza: 18% on 1.2 mg and 20% on 1.8 mg, against 5% on placebo. Diarrhea, headache, vomiting and decreased appetite followed. Withdrawals for stomach side effects happened mainly in the first 2 to 3 months. The label carries a boxed warning about thyroid C-cell tumors seen in rodents.
What Victoza is approved for: The label says Victoza is approved, along with diet and exercise, to improve blood sugar control in adults and children 10 years and older with type 2 diabetes. It is also approved to lower the risk of major heart events (heart death, non-fatal heart attack or non-fatal stroke) in adults with type 2 diabetes and established heart disease.
Source
VICTOZA (liraglutide) injection, for subcutaneous use, prescribing information and Medication Guide. Novo Nordisk. DailyMed, version published November 17, 2025. DailyMed setid 5a9ef4ea-c76a-4d34-a604-27c5b505f5a4
WARNING: RISK OF THYROID C-CELL TUMORS
Liraglutide caused thyroid C-cell tumors in rats and mice, and it is not known whether Victoza causes these tumors, including medullary thyroid carcinoma (MTC), in people. Victoza must not be used by people with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). The label lists a lump in the neck, trouble swallowing, shortness of breath and lasting hoarseness as possible thyroid tumor symptoms.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Victoza.
| Adverse reaction | Placebo N=661 (%) | Liraglutide 1.2 mg N= 645 (%) | Liraglutide 1.8 mg N= 1024 (%) |
|---|---|---|---|
| Nausea | 5 | 18 | 20 |
| Diarrhea | 4 | 10 | 12 |
| Headache | 7 | 11 | 10 |
| Nasopharyngitis | 8 | 9 | 10 |
| Vomiting | 2 | 6 | 9 |
| Decreased appetite | 1 | 10 | 9 |
| Dyspepsia | 1 | 4 | 7 |
| Upper Respiratory Tract Infection | 6 | 7 | 6 |
| Constipation | 1 | 5 | 5 |
| Back Pain | 3 | 4 | 5 |
Pooled from 5 placebo-controlled blood sugar trials in adults: 1,673 adults took Victoza for a mean of 37.3 weeks. Low blood sugar is not included in this table. The label says side effects in children 10 and older were comparable.
| Trial and event type | Placebo comparator | Victoza treatment |
|---|---|---|
| Add-on to Metformin (N=121 placebo, N=724 Victoza): Patient not able to self-treat | 0 | 0.1 (0.001) |
| Add-on to Metformin: Patient able to self-treat | 2.5 (0.06) | 3.6 (0.05) |
| Add-on to Glimepiride (N=114 placebo, N=695 Victoza): Patient not able to self-treat | 0 | 0.1 (0.003) |
| Add-on to Glimepiride: Patient able to self-treat | 2.6 (0.17) | 7.5 (0.38) |
| Add-on to Glimepiride: Not classified | 0 | 0.9 (0.05) |
| Add-on to Metformin + Rosiglitazone (N=175 placebo, N=355 Victoza): Patient not able to self-treat | 0 | 0 |
| Add-on to Metformin + Rosiglitazone: Patient able to self-treat | 4.6 (0.15) | 7.9 (0.49) |
| Add-on to Metformin + Rosiglitazone: Not classified | 1.1 (0.03) | 0.6 (0.01) |
| Add-on to Metformin + Glimepiride (N=114 placebo, N=230 Victoza): Patient not able to self-treat | 0 | 2.2 (0.06) |
| Add-on to Metformin + Glimepiride: Patient able to self-treat | 16.7 (0.95) | 27.4 (1.16) |
| Add-on to Metformin + Glimepiride: Not classified | 0 | 0 |
Four 26-week add-on trials in adults. Each cell is the percent of patients, with episodes per patient year in brackets. "Patient not able to self-treat" means an event that needed another person's help.
Withdrawals because of stomach and gut side effects: 4.3% on Victoza and 0.5% on placebo, mainly in the first 2 to 3 months. Severe stomach and gut side effects: 4.4% on 1.2 mg, 4.2% on 1.8 mg and 1.1% on placebo.
Injection site reactions (such as rash or redness) were reported in about 2% of adults on Victoza; less than 0.2% stopped because of them.
In children 10 and older, 21.2% on Victoza had blood sugar below 54 mg/dL, with no severe low blood sugar episodes in the Victoza group.
Pancreatitis: 13 cases on Victoza versus 1 on a comparator (2.7 vs 0.5 cases per 1,000 patient-years). Papillary thyroid cancer: 7 cases versus 1 (1.5 vs 0.5 per 1,000 patient-years).
Heart rate rose by a mean of 2 to 3 beats per minute versus placebo; the label says Victoza did not have adverse effects on blood pressure.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Risk of thyroid C-cell tumors. Liraglutide caused thyroid C-cell tumors in rats and mice, and cases of MTC have been reported after marketing. People with a personal or family history of MTC or with MEN 2 must not use Victoza.
Acute pancreatitis. Inflammation of the pancreas, including fatal cases, has been seen with GLP-1 drugs including liraglutide. The label says to stop Victoza if pancreatitis is suspected.
Never share a pen. Victoza pens must never be shared between people, even if the needle is changed, because of the risk of passing on blood-borne infections.
Low blood sugar. Adults using Victoza with a sulfonylurea or insulin may have a higher risk of low blood sugar. In children 10 and older, the risk was higher with Victoza regardless of insulin or metformin use.
Kidney injury from fluid loss. Acute kidney injury, sometimes needing dialysis, has been reported, mostly in people who became dehydrated from nausea, vomiting or diarrhea. The label says to monitor kidney function in these people, especially when starting or raising the dose.
Severe stomach and gut side effects. Severe stomach and gut side effects were reported in 4.4% on 1.2 mg and 4.2% on 1.8 mg, against 1.1% on placebo. Victoza is not recommended in people with severe gastroparesis.
Allergic reactions. Serious allergic reactions such as anaphylaxis and angioedema have been reported after marketing. The label says to stop Victoza if one occurs.
Gallbladder disease. In the LEADER trial, 3.1% on Victoza versus 1.9% on placebo had an acute gallbladder event such as gallstones or gallbladder inflammation.
Food or liquid in the lungs during anesthesia. Victoza slows stomach emptying. Rare reports describe food entering the lungs during procedures with general anesthesia or deep sedation. The label says to tell your providers you take Victoza before any planned procedure.
From the Medication Guide that comes with Victoza:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.