When Injection Site Reactions on Zepbound (Tirzepatide) Become a Reason to Stop

What the Zepbound label records as an injection site reaction

Table 1 of the Zepbound prescribing information groups several events under one heading: injection site bruising, injection site erythema, injection site pruritus, injection site pain, injection site rash and injection site reaction [1]. In the pooled weight-management trials (Study 1 and Study 2, up to 72 weeks), that grouped rate was 2% on placebo, 6% on 5 mg, 8% on 10 mg and 8% on 15 mg [1]. Injection site reactions also appear on the label's list of adverse reactions reported in at least 5% of treated patients [1].

The skin reaction the label says to stop for

Serious hypersensitivity is the event the label acts on. Anaphylaxis and angioedema have been reported after marketing, and in the pooled weight-management studies 0.1% of Zepbound-treated patients had a severe hypersensitivity reaction compared with none on placebo [1]. The label says that if a hypersensitivity reaction occurs, patients should promptly seek medical attention and discontinue Zepbound [1]. A known serious hypersensitivity to tirzepatide or any excipient in Zepbound is a contraindication [1].

Why people stopped in the trials

Across the pooled weight-management trials, 4.8% of patients on 5 mg, 6.3% on 10 mg and 6.7% on 15 mg stopped treatment because of an adverse reaction, versus 3.4% on placebo; the label says the majority of those who stopped did so during the first few months because of gastrointestinal reactions [1]. Discontinuation due to gastrointestinal reactions specifically was 1.9%, 3.3% and 4.3% versus 0.5% [1].

Skin pain the injection site heading does not cover

A 2026 case series described two patients with severe obesity treated with tirzepatide who developed moderate-to-severe cutaneous allodynia, meaning pain from a stimulus that does not normally cause pain, such as light touch [2]. In both, the sensitivity was temporally associated with dose escalation, was related to higher doses, and resolved after the drug was stopped [2]. The authors note that the tirzepatide prescribing information lists hypersensitivity and injection site reactions as its dermatological adverse events and does not describe skin pain or allodynia [2]. Two patients make a case series, not a rate.

Do antibodies explain recurring reactions?

Anti-tirzepatide antibodies were detected in 64.5% of Zepbound-treated patients in weight trials 1 and 2, with no clinically significant effect on pharmacokinetics or effectiveness found [1]. In a pooled analysis of seven phase 3 trials in 5,025 patients with type 2 diabetes, treatment-emergent antibodies developed in 51.1%, and neutralizing antibodies against tirzepatide activity at the GIP and GLP-1 receptors were found in 1.9% and 2.1% [3]. More antibody-positive patients had hypersensitivity or injection site reactions than antibody-negative patients, but the majority of those events were nonserious and nonsevere, and most occurred or resolved regardless of antibody status or titer [3].

Rotating sites

The label describes injections into the abdomen, thigh, or back of the upper arm, with the upper arm given by another person, and recommends rotating injection sites [1]. Exposure is similar whether the drug goes into the abdomen, thigh or upper arm [1].

If the drug is stopped

In SURMOUNT-4, 783 adults received open-label tirzepatide for 36 weeks and 670 were then randomized to continue or switch to placebo. From week 36 to week 88, weight changed by -5.5% in those who continued and +14.0% in those who switched to placebo [4]. Stopping the drug led to substantial weight regain in that trial.