A patient who tolerated dulaglutide without problems developed an injection site rash after switching to tirzepatide, marking the first documented case of this reaction.
First reported caseThis is the first documented tirzepatide-induced injection site reaction, notable because the patient had tolerated a different GLP-1 receptor agonist without adverse skin effects.
What the researchers found
A man in his 70s developed an injection site rash on his lower abdomen after switching from dulaglutide (a GLP-1 RA) to tirzepatide (a dual GIP/GLP-1 RA). The rash resolved after stopping tirzepatide. Notably, the patient had tolerated dulaglutide without any injection site reactions, indicating a tirzepatide-specific skin reaction. This was reported as the first documented case of tirzepatide-induced injection site reaction.
Why it matters
As tirzepatide rapidly gains prescriptions for diabetes and obesity, documenting its adverse effects is important for clinicians. This case shows that patients who tolerate one GLP-1 RA may still develop reactions to tirzepatide, which has a different molecular structure as a dual GIP/GLP-1 receptor agonist. Clinicians should be aware that switching between peptide drugs in this class doesn't guarantee the same tolerability profile.
The numbers in context
n=1 · male in his 70s · rash at injection site on lower abdomen · resolved after stopping tirzepatide · no reaction with prior dulaglutide use
How the study worked
This is a single case report documenting the clinical presentation, timeline, and resolution of an injection site reaction after switching from dulaglutide to tirzepatide.
Who was studied
Male patient in his 70s with diabetes, previously on dulaglutide, switched to tirzepatide
What this study cannot tell us
As a single case report, this represents an isolated observation that cannot establish the frequency or risk factors for tirzepatide injection site reactions. No allergy testing or skin biopsy was described to characterize the nature of the reaction. The mechanism of the tirzepatide-specific reaction was not investigated.
How to read the evidence
This is a single case report (n=1), the lowest level of clinical evidence. It documents a novel adverse event but cannot establish incidence rates, risk factors, or mechanism.
When this study was published
Published in 2023, this early case report was among the first to document tirzepatide injection site reactions as the drug entered widespread clinical use.
The bigger picture
As tirzepatide prescriptions surge worldwide, post-marketing surveillance of adverse effects becomes increasingly important. This case adds injection site reactions to the known side effect profile of tirzepatide. Since tirzepatide has a unique dual-agonist structure (targeting both GIP and GLP-1 receptors), it may provoke immune responses different from pure GLP-1 agonists, warranting attention as the drug reaches millions of patients.
Questions still open
- Is the injection site reaction caused by tirzepatide's unique dual GIP/GLP-1 peptide structure or by its formulation excipients?
- How common are tirzepatide injection site reactions in larger population studies?
- Could desensitization protocols allow patients with injection site reactions to continue tirzepatide therapy?
Common questions
Why might tirzepatide cause a reaction when another GLP-1 drug didn't?
Are injection site reactions with peptide drugs common?
Read the original research
Tirzepatide-Induced Injection Site Reaction.
Cureus, 15(9), e45181
Citation
Mizumoto, Junki. (2023). Tirzepatide-Induced Injection Site Reaction.. Cureus, 15(9), e45181. https://doi.org/10.7759/cureus.45181