Short answer: In the label's 30-week trials with metformin and/or a sulfonylurea, the most common Byetta side effects were nausea (44% vs 18% on placebo), vomiting (13% vs 4%), diarrhea (13% vs 6%), feeling jittery, dizziness and headache (9% each). Nausea depended on dose and eased over time for most people. Byetta has no boxed warning.
What Byetta is approved for: Byetta is approved, along with diet and exercise, to improve blood sugar control in adults with type 2 diabetes. The label says not to use it with other exenatide products (section 1).
Source
BYETTA (exenatide) injection, prescribing information and Medication Guide. AstraZeneca. DailyMed, version published September 8, 2025. DailyMed setid 53d03c03-ebf7-418d-88a8-533eabd2ee4f
No. The current Byetta label has no boxed warning.
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 Byetta.
| Adverse reaction | Placebo BID (N=483) % | All Byetta BID (N=963) % |
|---|---|---|
| Nausea | 18 | 44 |
| Vomiting | 4 | 13 |
| Diarrhea | 6 | 13 |
| Feeling Jittery | 4 | 9 |
| Dizziness | 6 | 9 |
| Headache | 6 | 9 |
| Dyspepsia | 3 | 6 |
| Asthenia | 2 | 4 |
| Gastroesophageal Reflux Disease | 1 | 3 |
| Hyperhidrosis | 1 | 3 |
Three 30-week placebo-controlled trials. BID means twice daily; the Byetta column combines the 5 mcg and 10 mcg doses.
| Adverse reaction | Placebo BID (N=77) % | All Byetta BID (N=155) % |
|---|---|---|
| Nausea | 0 | 8 |
| Vomiting | 0 | 4 |
| Dyspepsia | 0 | 3 |
One 24-week placebo-controlled trial of Byetta on its own.
Nausea was the most frequent reaction and depended on dose. With continued treatment, its frequency and severity decreased over time in most people who had it.
Stopping because of side effects: nausea 3% and vomiting 1% on Byetta; on placebo under 1% stopped for nausea and none for vomiting.
With a thiazolidinedione (16 weeks): nausea 40% vs 15% on placebo, vomiting 13% vs 1%, indigestion 7% vs 1%, diarrhea 6% vs 3%.
Low blood sugar with a sulfonylurea (30 weeks): 14.4% on 5 mcg and 35.7% on 10 mcg vs 3.3% on placebo. With metformin alone it was 4.5% and 5.3% vs 5.3%.
Gallbladder disease (gallstones or inflammation) was reported in 1.9% on exenatide vs 1.4% on placebo in one study.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Acute pancreatitis. Inflammation of the pancreas, including fatal cases, has been seen with this drug class, including Byetta. If it is suspected, Byetta is stopped.
Never share a pen. Byetta pens must never be shared, even with a new needle, because of the risk of passing on blood-borne infections.
Low blood sugar with insulin or sulfonylureas. Using Byetta with a sulfonylurea or insulin raises the risk of low blood sugar, including severe episodes. Lowering the dose of those medicines may reduce the risk.
Kidney injury from fluid loss. Kidney injury, sometimes needing dialysis, has been reported. Byetta is not recommended with severe kidney impairment (creatinine clearance under 30 mL/min) or end-stage kidney disease, and is used with caution after a kidney transplant.
Severe stomach and gut reactions. Gut side effects can be severe. Byetta is not recommended for people with severe gastroparesis.
Antibodies. Some people develop antibodies to exenatide. In a small share, high antibody levels weakened the blood sugar response.
Serious allergic reactions. Anaphylaxis and angioedema have been reported after approval. If an allergic reaction happens, Byetta is stopped.
Low platelets from the drug. Serious bleeding, sometimes fatal, from immune-related low platelets has been reported with exenatide. If it is suspected, Byetta is stopped right away and exenatide is not used again.
Gallbladder disease. Gallstones and gallbladder inflammation have been reported with this drug class. If gallstones are suspected, the label calls for gallbladder tests.
Breathing in stomach contents during anesthesia. Byetta slows stomach emptying. Rare cases of pulmonary aspiration under general anesthesia or deep sedation have been reported with this drug class; tell the care team before any procedure.
From the Medication Guide that comes with Byetta:
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.