Cagrilintide side effects and risks

Reported side effects

• Nausea: 20–47% across phase 2 doses versus 18% placebo., moderate. Persistent symptoms call for review before any increase. (source)
• Injection-site reactions: 16.9% at 2.4 mg alone versus 3.0% placebo in REDEFINE 1., mild (source)
• Gallbladder disorders: 2.3% at 2.4 mg alone versus 1.0% placebo in REDEFINE 1., serious (source)
• Fatigue and marked appetite loss: Reported online; reliable cagrilintide specific rates are unavailable., moderate (source)
• Serious allergic reaction: Risk is plausible; a reliable monotherapy anaphylaxis rate is unavailable., serious (source)
• Low blood sugar with insulin: Class based concern; 92 person diabetes trial reported no level 2/3 episodes., serious (source)
• Constipation: At 2.4 mg: 17/102 versus 7/101 placebo in the phase 2 registry., moderate (source)
• Diarrhea: At 2.4 mg: 18/102 versus 9/101 placebo in the phase 2 registry., moderate (source)
• Vomiting: At 2.4 mg: 9/102 versus 3/101 placebo in the phase 2 registry., moderate (source)

Stop and get help if

• Severe or persistent belly pain, especially with vomiting: Stop and seek urgent assessment for pancreatitis, gallbladder disease or obstruction.
• Throat swelling, breathing trouble or collapse: Stop and call emergency services for possible anaphylaxis.
• Confusion, fainting or low sugar that does not recover: Seek emergency care; do not give food or drink to an unconscious person.
• Cannot keep fluids down, very little urine or marked dizziness: Seek urgent care for dehydration or kidney injury.
• Persistent squeezing chest pain, or chest pain with breathlessness: Call emergency services.
• Sudden vision loss or a new major vision change: Get emergency care for sudden loss of sight; urgent assessment for other new changes.

Who should avoid it

• pregnant: Pregnancy was excluded; weight-loss use and fetal safety are not established.
• breastfeeding: Breastfeeding was excluded; infant exposure and safety are unknown.
• tryingToConceive: Conception attempts were excluded. A cagrilintide-specific washout is not established.
• under18: Adult results do not establish youth safety; pediatric trials are ongoing.
• eatingDisorderHistory: Precaution: appetite suppression can worsen restrictive eating or poor nutrition.
• gastroparesis: Amylin-class concern: delayed stomach emptying may worsen symptoms; cagrilintide-specific limits are unknown.
• diabetes: Review insulin, low-sugar risk and food intake before adding an appetite suppressant.
• kidneyDisease: Single-dose PK was reassuring; dehydration and repeated-dose safety still need review.
• liverDisease: Single-dose liver PK did not change meaningfully; chronic severe-disease safety remains uncertain.
• pancreatitisHistory: Review the history before use; monotherapy evidence in this group is limited.
• gallbladderDisease: Gallbladder events occurred in 2.3% of monotherapy users versus 1.0% placebo in REDEFINE 1.
• heartCondition: The QT study was reassuring but did not assess every heart risk.
• surgeryPlanned: Tell the anesthesia team about use; amylin-related stomach-emptying effects may matter.
• testedAthlete: Apply WADA S0 to an unapproved drug; obtain a current sport-specific ruling.
• other: A serious allergic reaction to the compound or an ingredient should stop further exposure.

Interactions

• Insulin and sulfonylureas: Amylin-class concern: less food and insulin exposure can cause low blood sugar; cagrilintide-specific risk is uncertain.
• Oral medicines with narrow dosing margins: Stomach-emptying effects may alter timing of absorption. Review drug levels or INR; a cagrilintide effect is not proven.
• Oral contraception: An interaction study exists but no results were found. Do not import tirzepatide’s four-week rule as cagrilintide evidence.
• Other amylin drugs: Avoid duplicate amylin exposure; the combination has no established safety schedule.
• GLP-1 and related weight-loss drugs: Semaglutide pairing has trial evidence. Tirzepatide and retatrutide stacks lack verified human combination evidence.

Product quality risks

• No independent cagrilintide retail-vial testing study was found.
• An online semaglutide study found 7.7–14.37% purity and endotoxin; those findings cannot be assigned as cagrilintide rates.
• Unapproved vials may have wrong identity, wrong dose, impurities or contamination.