Zepbound Side Effects: Potentially Permanent Adverse Events Explained

Which effects are usually temporary?

In the two pooled placebo-controlled weight-management trials of Zepbound (adults with obesity or overweight, with or without type 2 diabetes, up to 72 weeks), nausea occurred in 25% of patients on 5 mg, 29% on 10 mg and 28% on 15 mg, versus 8% on placebo. Diarrhea occurred in 19%, 21% and 23% versus 8%; vomiting in 8%, 11% and 13% versus 2%; constipation in 17%, 14% and 11% versus 5% [1]. The label states that the majority of nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time [1]. Any gastrointestinal adverse reaction was reported in 56% of patients on every Zepbound dose versus 30% on placebo, and treatment was discontinued for a gastrointestinal reason in 1.9%, 3.3% and 4.3% of the 5, 10 and 15 mg groups versus 0.5% on placebo [1].

Hair loss was reported in 5%, 4% and 5% of those dose groups versus 1% on placebo. The label associates hair loss with weight reduction and reports it far more often in women: 7.1% of women versus 0.5% of men on Zepbound, and 1.3% of women versus 0% of men on placebo. No Zepbound-treated patient discontinued treatment because of hair loss; one placebo-treated patient did [1].

Injection-site reactions were reported in 6%, 8% and 8% versus 2% on placebo, fatigue in 5%, 6% and 7% versus 3%, and dizziness in 4%, 5% and 4% versus 2% [1]. Mean heart rate rose by 1 to 3 beats per minute across the program [1]. The label does not describe any of these as irreversible.

Gallbladder disease: the clearest route to an irreversible outcome

In the same pooled trials, gallstones (cholelithiasis) were reported in 1.1% of Zepbound-treated patients versus 1% on placebo, gallbladder inflammation (cholecystitis) in 0.7% versus 0.2%, and gallbladder removal (cholecystectomy) in 0.2% versus no placebo patients [1]. The label notes that acute gallbladder events were associated with weight reduction [1].

A cholecystectomy is permanent, which makes it the clearest lasting consequence tied to a labeled Zepbound risk. The label directs gallbladder studies and clinical follow-up if cholecystitis is suspected [1].

A 2023 systematic review and meta-analysis pooled nine randomized trials with 9,871 participants (6,828 on tirzepatide, 3,043 controls). The composite of gallbladder or biliary disease was significantly associated with tirzepatide when compared with placebo or basal insulin (relative risk 1.97, 95% CI 1.14 to 3.42), while the individual risks of cholelithiasis, cholecystitis or biliary disease were not [3]. That analysis groups trials of different designs and populations; it describes a signal, not what will happen to one person.

Pancreatitis: rare, serious, and sometimes destructive

The label warns that acute pancreatitis, including fatal and non-fatal hemorrhagic or necrotizing pancreatitis, has been observed in patients treated with GLP-1 receptor agonists or with Zepbound, and directs that Zepbound be discontinued if pancreatitis is suspected [1]. In the pooled weight trials, acute pancreatitis confirmed by adjudication occurred in 0.2% of Zepbound-treated patients (0.14 per 100 patient-years of exposure) and 0.2% of placebo-treated patients (0.15 per 100 patient-years) [1].

The label describes the symptoms to watch for: persistent or severe abdominal pain, sometimes radiating to the back, which may or may not be accompanied by nausea or vomiting [1]. The label does not say how long the effects of pancreatitis last. The meta-analysis above found no statistically significant increase in pancreatitis with tirzepatide (relative risk 1.46, 95% CI 0.59 to 3.61) [3].

Kidney injury from dehydration

The label warns about acute kidney injury due to volume depletion. Postmarketing reports have included cases requiring hemodialysis, and the majority occurred in patients who had gastrointestinal reactions such as nausea, vomiting or diarrhea that led to dehydration. The label advises monitoring renal function in patients reporting reactions that could lead to volume depletion, especially during dose initiation and escalation [1]. The label requires no dose adjustment for renal or hepatic impairment [1].

Gastroparesis and severe gastrointestinal reactions

The label states that Zepbound is associated with gastrointestinal adverse reactions, sometimes severe, and is not recommended in patients with severe gastroparesis [1]. Severe gastrointestinal reactions were reported in 1.7% of the 5 mg group, 2.5% of the 10 mg group and 3.1% of the 15 mg group, versus 1% on placebo [1]. The label also notes that tirzepatide's effect on gastric emptying is largest after the first dose and diminishes over time [1]. It does not state that Zepbound causes gastroparesis [1].

Thyroid C-cell tumors: a boxed warning with unknown human relevance

In a 2-year rat study, tirzepatide caused dose- and duration-dependent thyroid C-cell tumors (adenomas and carcinomas) at clinically relevant plasma exposures. The boxed warning states that it is unknown whether Zepbound causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans, because the human relevance of the rodent tumors has not been determined [1].

Zepbound is contraindicated in people with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 [1]. The label also says routine calcitonin monitoring or thyroid ultrasound is of uncertain value for early detection, may increase the risk of unnecessary procedures because of low test specificity and a high background rate of thyroid disease, and lists a neck mass, difficulty swallowing, difficulty breathing and persistent hoarseness as symptoms of thyroid tumors [1].

Serious allergic reactions and the lasting contraindication

Serious hypersensitivity reactions, including anaphylaxis and angioedema, have been reported in the postmarketing period with tirzepatide, and severe hypersensitivity reactions occurred in 0.1% of Zepbound-treated patients versus none on placebo in the pooled weight trials [1]. The label says to discontinue Zepbound if a hypersensitivity reaction occurs [1]. After a serious hypersensitivity reaction to tirzepatide or any Zepbound excipient, Zepbound is contraindicated [1]. That contraindication applies to Zepbound itself.

Weight regain after stopping is not tissue damage

SURMOUNT-4 enrolled 783 adults for 36 weeks of open-label tirzepatide at the maximum tolerated dose (10 or 15 mg); 670 of them were then randomized to continue tirzepatide or switch to placebo for 52 more weeks. Mean weight reduction during the lead-in was 20.9%. From week 36 to week 88, weight changed by -5.5% with continued tirzepatide and +14.0% after switching to placebo [2]. That is the weight effect reversing after the drug is withdrawn.