Larazotide side effects and risks

Reported side effects

• Headache: Six week trial: 1/4/8 mg, 7%/5%/12%; placebo 7%. All cause events, not proven drug effects., mild. Track persistent or worsening symptoms; review other causes. (source)
• Nausea: Six week trial: 1/4/8 mg, 10%/14%/9%; placebo 19%. Gluten challenge can cause the same symptoms., mild. Persistent vomiting or poor fluid intake needs clinical review. (source)
• Diarrhea: Six week trial: 1/4/8 mg, 17%/28%/19%; placebo 28%. These are all cause trial events., moderate. Track fluids and stools; blood, fainting or severe pain needs urgent care. (source)
• Bloating and gas: Six week trial: bloating 14%/12%/14%; gas 17%/14%/12% at 1/4/8 mg. Placebo: 19% and 14%., mild (source)
• Constipation: Six week trial: 1/4/8 mg, 12%/2%/16%; placebo 12%. Drug causation is uncertain., mild (source)
• Urinary infection: 14 day gluten challenge: 16.7%/8.3%/8.3%/8.3% at 0.25/1/4/8 mg; placebo 0%. Very small groups., moderate. Painful urination or fever needs assessment; a causal link is unproven. (source)
• Serious or delayed harm: No serious events in the 86 person trial; no drug related serious events in the 342 person trial. Long term rates are unknown., serious (source)

Stop and get help if

• Sudden severe abdominal pain, blood in vomit, or black or bloody stool: Get emergency assessment. Do not assume this is “gut healing” or a routine peptide effect.
• Throat or tongue swelling, trouble breathing, collapse or fainting after a dose: Call emergency services; use prescribed emergency adrenaline if available.
• Ongoing diarrhea, unexplained weight loss or persistent celiac symptoms: Arrange prompt assessment for gluten exposure, nutrient loss and other bowel disease.

Who should avoid it

• pregnant: No pregnancy safety data; celiac trials excluded pregnancy. This is a precaution, not a demonstrated fetal risk.
• breastfeeding: No milk-transfer or infant-safety data; breastfeeding participants were excluded from celiac trials.
• tryingToConceive: Reproductive safety is unknown. Celiac trials required contraception for participants who could become pregnant.
• under18: No routine pediatric regimen is established. Small MIS-C studies used hospital research or emergency access.
• other: Avoid a known allergy trigger; larazotide-specific allergy rates are unknown.
• kidneyDisease: No dedicated kidney-disease dose study found; oral trial safety does not establish dosing in severe kidney disease.
• liverDisease: No dedicated liver-disease dose study found; clinically important illness was excluded from celiac trials.
• other: Persistent symptoms need a cause-specific workup. Refractory disease and severe celiac complications were excluded from the main trial.
• testedAthlete: S0 inference: an unapproved investigational drug is prohibited at all times under the 2026 list; larazotide is not named individually.

Interactions

• Proton pump inhibitors and other acid-reducing drugs: Drugs changing gut pH were excluded from celiac trials. Effects on capsule release or drug absorption have not been measured.
• NSAID pain relievers: Regular NSAID use was excluded because it can affect gut measures. A harmful interaction with larazotide has not been shown.
• Immunosuppressants, corticosteroids and IVIG: Excluded from celiac trials, but steroids and IVIG were used in small MIS-C studies. Safety of other combinations is unknown.
• Other experimental gut peptides: Reported blends have no verified combination trial. Duplicate larazotide can hide the total daily dose.

Product quality risks

• No independent larazotide-specific market survey of purity, dose or sterility was found.
• FDA cited larazotide acetate among ineligible compounding ingredients in a 2025 supplier warning letter.
• General peptide alerts describe wrong ingredients, too much or too little drug, contamination and nonsterile injections. These are not larazotide-specific rates.
• An HPLC purity percentage does not establish identity, dose, sterility or gut-release performance.