The cagrilintide side effects reported across published trials are dominated by nausea, which scales steeply with dose, and by injection site reactions, which occur far more often with amylin analogues than with GLP-1 agonists. Most cagrilintide side effects are mild to moderate, concentrate during dose escalation, and settle at a stable dose, which is the same pattern seen across the incretin and amylin classes.
Cagrilintide is investigational and not approved anywhere. Everything below comes from supervised trials using pharmaceutical grade material, which is not the same situation as a research vial bought online.
Cagrilintide Side Effects Reported Most Often in Trials
| Effect | Approximate range across trials | Pattern |
|---|---|---|
| Nausea | Roughly 20 percent at low doses, rising toward 45 percent at the highest studied dose | Steeply dose dependent, worst during escalation |
| Injection site reactions | Substantially higher than placebo, reported by a large minority | Distinctive of amylin analogues |
| Vomiting | Roughly 10 to 20 percent | Tracks nausea |
| Constipation | Roughly 8 to 16 percent | Persists longer than nausea for some |
| Diarrhoea | Roughly 8 to 14 percent | Usually early and self limiting |
| Reduced appetite | Common and expected | The intended effect rather than an adverse one |
In combination arms pairing cagrilintide with semaglutide, the large majority of participants reported at least one gastrointestinal event over the full trial period. That figure sounds worse than it is: it counts any event of any severity across 68 weeks, and most were mild or moderate.
Why Nausea Scales So Sharply With Dose
Amylin acts on the area postrema, a brainstem region outside the blood brain barrier that is also the chemoreceptor trigger zone for vomiting. The same circuit that produces satiety signalling sits next to the one that produces nausea, which is why the two are difficult to separate pharmacologically.
Phase 2 dose finding showed the practical consequence clearly. At the lowest doses tested, nausea rates were only modestly above placebo. At the highest dose, they approached half of participants. The 2.4 mg maintenance dose taken into phase 3 sits between those poles, and its tolerability depends heavily on stepwise escalation over several weeks rather than starting near target.
Injection Site Reactions Are the Distinctive One
This is where the amylin profile diverges most clearly from GLP-1 drugs. Redness, itching, swelling and a palpable lump at the site occur at rates well above placebo and well above what semaglutide produces.
The reactions are generally local, mild and self limiting, resolving over days. Rotating sites, allowing the solution to reach room temperature before injecting, and slower delivery are the mitigations most often described.
What matters clinically is distinguishing a local reaction from infection. Spreading redness, warmth, fever, or pus point toward infection and need medical attention rather than reassurance.
Timing
| Period | What typically happens |
|---|---|
| Week 1 of any dose step | Nausea peaks, appetite drops sharply |
| Weeks 2 to 4 at a stable dose | Nausea settles substantially for most people |
| Ongoing | Constipation is the effect most likely to persist |
| Each escalation | The cycle restarts, usually less severely each time |
The single most useful lever on tolerability is escalation speed. Slowing it costs a few weeks and removes most of the severe events.
Two other patterns come up consistently across the incretin and amylin classes. Effects are worst in the days immediately after an injection and ease before the next one, which is why moving injection day to a point in the week where a rough evening matters less is a common adjustment. And appetite suppression is not an adverse event, though it is often reported as one by people who did not expect how complete it would be.
Discontinuation is the number worth watching in any trial report. Rates of individual side effects tell you how often something was noticed. Discontinuation tells you how often it was bad enough to stop, which is the figure that predicts real world use.
Serious Events
Serious adverse events in the published trials were uncommon and generally comparable between active and placebo arms. Discontinuation due to gastrointestinal effects occurred at higher rates in the active arms, which is the more informative number: some people simply cannot tolerate the escalation.
Two areas remain genuinely open rather than resolved.
Bone metabolism. Cagrilintide has activity at the calcitonin receptor, and calcitonin influences bone turnover. Whether long term amylin analogue use affects bone density is being investigated rather than answered. This is a reasonable question to raise, not a demonstrated risk.
Long term use. The longest published trials run to 68 weeks. Nothing is known about multi year use, because nobody has done it.
How It Compares With GLP-1 Drugs
| Effect | Cagrilintide | Semaglutide |
|---|---|---|
| Nausea | Common, dose dependent | Common, dose dependent |
| Injection site reactions | Notably more frequent | Uncommon |
| Constipation | Common | Common |
| Gallbladder events | Not a prominent signal in published data | Recognised with rapid weight loss |
| Pancreatitis warning | Not established for this class | Labelled concern for GLP-1 agonists |
Combining the two does not simply add the gastrointestinal burdens together, which is part of why the combination was pursued. It does increase them, and the discontinuation rates in combination arms reflect that.
For the wider picture see our cagrilintide guide and the CagriSema guide.
FAQ
How common is nausea with cagrilintide?
It varies with dose. Low doses produced nausea in roughly a fifth of participants, and the highest studied dose in close to half. Escalating gradually reduces both the frequency and the severity substantially.
Are cagrilintide injection site reactions dangerous?
Usually not. They are local, mild and resolve over days, though they occur far more often than with GLP-1 drugs. Spreading redness, fever or discharge suggests infection rather than a drug reaction and needs medical assessment.
Do cagrilintide side effects go away?
Most gastrointestinal effects settle within two to four weeks at a stable dose. Constipation is the one most likely to persist. Each dose increase restarts the cycle, generally less severely than the first time.
Is cagrilintide harder to tolerate than semaglutide?
The gastrointestinal profiles are broadly similar at comparable stages of escalation. Injection site reactions are clearly more common with cagrilintide. In combination, the burden is higher than with either compound alone.
Does cagrilintide cause hypoglycaemia?
It suppresses glucagon but does not stimulate insulin secretion the way a sulfonylurea does, and low blood sugar was not a prominent finding in the published trials. Risk would be different for anyone also taking insulin or an insulin secretagogue.
