Short answer: In the Gattex label's adult placebo-controlled trials, the most common side effects were abdominal pain (30% vs 22% on placebo), nausea (23% vs 20%), upper respiratory infection (21% vs 12%), abdominal swelling (20% vs 2%), injection site reactions (13% vs 12%), vomiting and fluid overload (12% each). There is no boxed warning; the label warns about faster growth of abnormal cells, polyps, bowel blockage and fluid overload.
What Gattex is approved for: Gattex is a glucagon-like peptide-2 (GLP-2) analog approved for adults and children 1 year of age and older with short bowel syndrome (SBS) who depend on parenteral support, meaning extra nutrition or fluids given by vein (section 1).
Source
GATTEX (teduglutide) for injection, for subcutaneous use, prescribing information, Medication Guide and Instructions for Use. Takeda. DailyMed, version published September 18, 2025. DailyMed setid 66b69c1e-b25c-44d3-b5ff-1c1de9a516fa
No. The current Gattex 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 Gattex.
| Adverse Reaction | Placebo (N=59) (%) | GATTEX 0.05 mg/kg Once Daily (N=77) (%) |
|---|---|---|
| Abdominal pain | 22 | 30 |
| Nausea | 20 | 23 |
| Upper respiratory tract infection | 12 | 21 |
| Abdominal distension | 2 | 20 |
| Injection site reaction | 12 | 13 |
| Vomiting | 10 | 12 |
| Fluid Overload | 7 | 12 |
| Hypersensitivity | 7 | 10 |
| Flatulence | 7 | 9 |
| Decreased appetite | 3 | 7 |
| Influenza | 2 | 7 |
| Skin hemorrhage | 2 | 5 |
| Cough | 0 | 5 |
| Sleep disturbances | 0 | 5 |
136 adults with short bowel syndrome in two 24-week, double-blind trials. Only reactions reported in at least 5% of the Gattex group and more often than placebo are listed. Several rows group related terms: for example, abdominal pain includes upper and lower abdominal pain, and fluid overload includes swelling of the legs and fluid retention.
In people with a stoma, stoma complications happened in 42% (13 of 31) on Gattex vs 14% (3 of 22) on placebo.
Bowel blockage or narrowing happened in 3 of 77 (4%) on the label dose and 3 of 32 (9%) on twice the label dose in the placebo-controlled trials, and in no one on placebo. 6 more adults had it in the longer extension studies.
Swelling of the legs was reported in 10% on Gattex vs 3% on placebo, and there were 2 cases of congestive heart failure (3%) on Gattex.
14 adults were found to have polyps of the digestive tract after starting treatment, most in the extension studies. 3 adults were diagnosed with cancer, all on Gattex: one with metastatic adenocarcinoma of unknown origin and two with lung cancer who had long smoking histories.
In 41 children aged 1 to under 17 years treated for 12 or 24 weeks, the side effects were similar to those in adults.
Reported after approval: polyps of the colon, stomach and small intestine, and injection site hardening, inflammation, itching, hives and warmth.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Faster growth of abnormal cells and polyps. Based on animal studies, Gattex may speed the growth of abnormal cells, including cancer. Adults have a colonoscopy and upper endoscopy with polyp removal within 6 months before starting, again after 1 year, then at least every 5 years. Children have a stool blood test before starting and every year, and a colonoscopy after 1 year and then every 5 years. Gattex is stopped if a digestive tract cancer is found.
Intestinal obstruction. Bowel or stoma blockage has been reported. Gattex is paused while the blockage is managed and may be restarted once it clears.
Gallbladder, bile duct and pancreas disease. Gallbladder inflammation, bile duct inflammation, gallstones and pancreatitis have been reported. Blood tests for bilirubin, alkaline phosphatase, lipase and amylase are done within 6 months before starting and at least every 6 months during treatment.
Fluid overload and fluid imbalance. Gattex increases fluid absorption, and fluid overload and congestive heart failure have been seen. IV support is adjusted if this happens. Stopping Gattex can also cause fluid and electrolyte imbalance, so these are checked after it is stopped.
More absorption of oral medicines. Gattex may increase how much of other medicines taken by mouth is absorbed. One person on the benzodiazepine prazepam fell into a coma in the first week. People on oral medicines that need careful dosing are watched, and those doses may need to be lowered.
Who should not use it. The label lists no contraindications.
From the Medication Guide that comes with Gattex:
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.