A 57-year-old man with type 2 diabetes started a weekly injection to get his blood sugar under control. About two weeks later, his family and his coworkers told him he smelled bad.
Nothing about his life had changed. Not his diet, not his hygiene habits, not any of his other prescriptions. The only new variable was dulaglutide, the once-weekly GLP-1 receptor agonist sold in the United States as Trulicity. His doctors ran the odor down to the drug, then confirmed it the hard way: they stopped the medication, watched the smell disappear, gave the drug again, and watched it come back.
The case appears in the August issue of the International Journal of Clinical Pharmacology and Therapeutics and was posted online in May. Its authors, Srecko Marusic, Matea Staresinic and Maja Cigrovski Berkovic, report it as a first: unpleasant body odor has not previously been recognized as an adverse effect of this drug.
His Coworkers Noticed It Before Any Test Did
He had lived with type 2 diabetes for six years and also had high blood pressure. Clinicians added dulaglutide because his glucose control was inadequate and he had obesity, which is the standard reason this class of drug gets prescribed.
Roughly two weeks after his first injection, family members and colleagues began commenting on the odor. He reported no change in diet, hygiene practices or concomitant medications.
That is when the workup started. A dermatological examination and extensive laboratory testing excluded infectious, metabolic and endocrine causes. The thoroughness makes sense once you know how ordinary body odor actually works. Apocrine gland secretions are sterile and odorless on their own, and only turn pungent once bacteria on the skin break them down into volatile acids. Drugs can intrude on that process. The Merck Manual already lists penicillin, alongside foods such as garlic, curry and onion, among the things that can change how a person smells.
In this man, every likely driver came back negative.
Stopping the Injection Cleared It, Restarting It Brought It Back
Dulaglutide was withdrawn. The odor resolved in about 10 days.
Then came the step that turns an anecdote into evidence. The patient was rechallenged with dulaglutide, and the odor returned. In pharmacology, this stop-and-restart sequence is the closest thing to a controlled experiment available in a single patient.
The team scored the link using the Naranjo Adverse Drug Reaction Probability Scale, a 10-question tool that assigns points for timing, response to withdrawal, response to rechallenge and whether alternative explanations exist. Total scores run from minus 4 to plus 13, with 9 or above rated definite, 5 to 8 probable, and 1 to 4 merely possible. The authors classified this reaction as probable.
Dulaglutide was permanently discontinued. The patient was switched to semaglutide, another GLP-1 receptor agonist. The odor did not come back, and his blood sugar control improved.
That last detail is the practical one. A reaction to one drug in a class did not mean the whole class was off limits for this patient.
Nothing in the Published Dulaglutide Case Files Matched This
Dulaglutide is not a new or obscure medicine. It has been on the US market since 2014, and its prescribing informationruns through nausea, vomiting, diarrhea, pancreatitis, hypoglycemia, gallbladder disease, serious hypersensitivity reactions and a boxed warning about thyroid tumors seen in rats. The postmarketing section even logs altered taste and hair loss. Body odor is not on the list.
Neither is it in the published case literature. A literature review in Frontiers in Pharmacology, published at the end of January, pulled together every dulaglutide adverse-reaction case report its authors could find from September 2014 through March 2025. That search returned 21 articles covering 22 patients, reported between 2017 and 2024. The reactions clustered in the skin and its appendages (six cases), the digestive system (five) and the circulatory system (five), and included rashes, bullous pemphigoid, pancreatitis, liver injury and one allergy-triggered coronary syndrome. Odor appears nowhere in that tally.
There has been a faint signal elsewhere, though not for this drug. A disproportionality study of FDA adverse event reports covering five GLP-1 medicines flagged breath odor as one of a handful of events turning up in the database without appearing in product labeling. Those particular signals attached to liraglutide and semaglutide, not dulaglutide. Breath odor and body odor are not the same phenomenon in any case, and a reporting signal establishes no mechanism.
The authors of the new report do not propose one either. They documented a reproducible reaction. The biology behind it remains unexplained.
Cosmetic Side Effects Are the Ones That Quietly End Treatment
One patient is one patient. This case says nothing about how often the reaction happens, and there is no basis for telling anyone on a GLP-1 drug to expect it.
What gives it weight is the size of the population now exposed. In 2024, 26.5% of American adults with diagnosed diabetes used GLP-1 injectables to lower blood sugar or lose weight, roughly 6.9 million people, according to National Health Interview Survey data. Separately, Gallup put current use of GLP-1 medicines for weight loss at 11% of US adults in a survey fielded in late May and early June, up from 3% two years earlier. Even a rare reaction reaches a lot of people at that scale.
The authors make the point that a side effect does not have to be dangerous to matter. They call it "a rare and previously unreported adverse effect of dulaglutide" and note that drug-induced body odor, while not medically serious, may substantially impair quality of life and treatment adherence. A patient who quietly abandons a diabetes medication because of social embarrassment ends up with worse glucose control, and the reason may never make it into the chart.
Anyone who notices an unexplained new symptom after starting a medication should raise it with the prescriber rather than stopping on their own, since interrupting diabetes treatment carries its own risks. Patients and clinicians in the US can also report suspected reactions directly to the FDA through the MedWatch program, which is how signals like this one eventually accumulate into something regulators can act on.
Key Questions Answered
What actually happened to the patient?
About two weeks after starting weekly dulaglutide injections for type 2 diabetes, a 57-year-old man developed an unpleasant body odor noticed by family and coworkers. Testing ruled out infectious, metabolic and endocrine causes.
How did doctors conclude the drug was responsible?
The odor resolved about 10 days after dulaglutide was stopped and returned when the drug was given again. That withdrawal-and-rechallenge pattern is the strongest causal evidence available from a single patient.
Is body odor a listed side effect of Trulicity?
No. It does not appear in the US prescribing information, and a January review of 21 published dulaglutide case reports covering 22 patients found no odor cases.
Does this mean GLP-1 drugs cause body odor?
No. This is one published case. It does not establish frequency or a class effect, it offers no basis for predicting who might be affected, and the report identifies no biological mechanism.
Did the patient have to give up GLP-1 treatment entirely?
No. He was switched to semaglutide, a different GLP-1 receptor agonist. The odor did not recur and his blood sugar control improved.
What should someone do if they notice a new symptom on a GLP-1 medication?
Bring it to the prescriber rather than stopping the drug independently. Suspected reactions can also be reported to the FDA through MedWatch.
