Cagrilintide common uses, half-life, side effects and more

Cagrilintide is a long-acting synthetic version of amylin. Amylin is a hormone the pancreas releases alongside insulin to signal fullness after a meal. Cagrilintide is in development as a once-weekly injection for weight loss. It is not approved by any health authority in any country. There is no legitimate prescription supply. A fixed-dose combination with semaglutide is under regulatory review and is also unapproved. People who obtain cagrilintide use research-grade material of unverified identity, strength, and sterility.

• Weight loss and obesity
• Appetite suppression and early fullness
• Restarting weight loss that has stalled on a GLP-1
• Lowering an existing GLP-1 dose while keeping appetite control
• Blood sugar control in type 2 diabetes alongside semaglutide

Once weekly

Once-weekly subcutaneous injection. Phase 2 tested 0.3 mg, 0.6 mg, 1.2 mg, 2.4 mg, and 4.5 mg. The 2.4 mg dose produced 9.7% weight loss at 26 weeks and 4.5 mg produced 10.8%. Phase 3 used 2.4 mg. That dose produced 11.5% weight loss at 68 weeks. Community users run much lower amounts than the trials. They usually start at 0.1 mg to 0.25 mg, raise the dose by about 0.1 mg every 3 to 4 weeks, and settle between 0.5 mg and 1 mg. Reports of severe nausea and fatigue cluster at 0.5 mg and above. Cagrilintide is almost always added to an existing GLP-1 rather than run on its own.

• Community practice is to inject cagrilintide 1 to 4 days apart from the weekly GLP-1 rather than at the same time so side effects stay traceable to one drug
• Syringe unit counts are not transferable between people because the reconstitution volumes in circulation vary about fourfold
• Community titration is deliberately slower than the trial ladder that doubled the dose every 2 to 4 weeks

About 7 to 8 days (159 to 195 hours) in humans. This supports once-weekly subcutaneous dosing.

Cagrilintide is formulated at an acidic pH of about 3.5 to 4.5. Plain bacteriostatic water sits closer to neutral and can push the solution to the point where the peptide loses its charge and clumps out of solution. A cloudy vial is the visible sign of that. Community practice is to reconstitute with 0.6% acetic acid water alone or mixed with bacteriostatic water to hold the pH near 4. Acetic acid water not made for injection carries its own contamination risk. Whether plain bacteriostatic water causes real potency loss or only cloudiness is unsettled.

• Nausea that peaks during dose increases and settles afterwards (about 24% at 2.4 mg against 13% on placebo)
• Injection-site redness, itching, and rash at about 17% on 2.4 mg against 3% on placebo
• Fatigue that climbs steeply with dose and reached about 20% at 4.5 mg against 3% on placebo
• Constipation that holds steady instead of easing once the dose stops rising
• Vomiting, diarrhea, dizziness, and hair shedding
• Gallbladder problems (uncommon and linked to rapid weight loss)

Cagrilintide activates the amylin receptors and the calcitonin receptor with almost no preference between them. Amylin receptors are built from the calcitonin receptor paired with one of three accessory proteins called RAMP1, RAMP2, and RAMP3. Older amylin drugs favor the amylin receptors over the calcitonin receptor. Cagrilintide does not. A C20 fatty diacid chain attached at the first amino acid binds albumin in the blood and stretches dosing out to once weekly. There is no settled account of how the weight loss happens in people. Mouse studies show the effect needs amylin receptors in the brainstem. They trace it to the area postrema and the lateral parabrachial nucleus. No human imaging or appetite study of cagrilintide on its own has been published. The one human test of gastric emptying used the semaglutide combination and found no slowing.

Human evidence for cagrilintide on its own is real but narrow. A 706-person phase 2 dose-finding trial ran 26 weeks. A 302-person cagrilintide-only arm inside a phase 3 combination trial ran 68 weeks and is the longest published exposure. A second phase 3 combination trial in type 2 diabetes carries a 152-person cagrilintide-only arm. Two dedicated single-drug phase 3 trials started in late 2025 and report in 2027. Most published cagrilintide data comes from trials of the semaglutide combination. Benefits and side effects attributed to cagrilintide are often the combination's. No cardiovascular outcomes trial has finished and no pregnancy exposure data exists. Public pages offering cagrilintide dosing advice often reprint trial numbers or invent titration schedules. One widely-read page states a starting dose roughly five times what experienced users take.

• Rat and mouse studies found major fetal malformations at exposures close to human dose levels and the cause has never been identified
• Cagrilintide is not for use in pregnancy, breastfeeding, or attempts to conceive
• Gray-market cagrilintide is unapproved and can vary in purity, dose accuracy, and sterility
• Cagrilintide cannot legally be used in compounded medicines in the United States and at least one state pharmacy board has threatened license suspension over it
• An overshoot cannot be undone because the drug takes more than a week to clear
• Long-term salmon calcitonin treatment showed a small unexplained rise in overall cancer risk and cagrilintide acts on the same receptor