Your box arrived warm. Maybe it sat on a porch in August, or the cold pack was already soft when you opened it. You want to know one thing: is the medicine still good?
Follow FDA’s current advice for injectable GLP-1 medicines: do not use a warm or inadequately refrigerated arrival [5]. The research below explains why laboratory findings do not validate a particular finished shipment. For the rules that apply before a parcel ever goes astray, see how to store peptides.
What sellers tend to say
The common reassurance is a specific one. A telehealth seller reviewed on this site answers it by saying that studies have shown compounded GLP-1 injections typically remain stable at temperatures as high as 104 °F for up to three days.
That is a precise claim. It names a temperature, a duration and a class of drug. What it does not name is a study. So the first useful question is simple: which studies, and what did they measure?
What the research actually measured
Semaglutide is a 31-amino-acid peptide with a fatty diacid chain attached so it binds albumin[1]. Researchers describe peptides as fragile and prone to degrading during formulation, storage and transport, which is why they stress-test them on purpose [1].
One 2025 study held semaglutide in solution at 25 °C, 40 °C and 60 °C for 28 days, and at 80 °C for seven [1]. Note the middle figure. 40 °C is 104 °F, the exact temperature in the seller claim above.
Across those conditions the researchers identified thirteen known impurities [1]. Six of them formed in every condition tested, including the mildest. Impurities matter because they can affect safety, efficacy and immunogenicity, not only potency.
The half that argues the other way
A second 2025 study found semaglutide remained stable for three hours at 80 °C under its laboratory conditions [2]. That result concerns the material and test conditions in the paper. It does not establish a safe shipping excursion for a finished medicine or override FDA’s recommendation.
A 2026 study looked at the dry solid rather than the solution. Semaglutide kept its native α-helical shape up to 60 °C [3]. Helical content fell from 49.07% to 43.75% at 60 °C, then collapsed to 0.2% at 80 °C.
These findings show that degradation depends on temperature, duration and formulation. They cannot establish the quality of a particular shipment. FDA’s advice about warm injectable GLP-1 arrivals remains the practical recommendation [5].
Why none of it answers your question
Every figure above comes from a preformulation study. That means researchers stressing the raw drug in chosen buffers to learn how to design a product [1] [2].
Your vial is not raw drug in a chosen buffer. It is a finished compounded product, at a pH and in a formulation you cannot see, made by a pharmacy the seller often does not name. What compounded status means in law is covered in are peptides legal.
Formulation is not a detail here. One study found degradation was worst between pH 4.5 and 5.5, near semaglutide’s isoelectric point of 5.4, and concluded a finished product should sit above pH 7.0[2]. Two vials at the same temperature can behave differently if their pH differs.
What to do with a warm parcel
Document the problem and obtain a pharmacy resolution before using the product.
- Photograph the parcel, the cold pack and any temperature indicator before you unpack further.
- Do not use injectable GLP-1 medicine that arrived warm or insufficiently refrigerated; FDA advises against it [5].
- Contact the dispensing pharmacy and the seller about replacement, return and storage while the issue is being resolved. Policies differ; a free replacement is not guaranteed.
- Ask which pharmacy compounded it, and whether that pharmacy has a written excursion limit.
- Ask your prescriber before using anything you are unsure about.
If a seller cites a study to reassure you, ask whether it tested the same finished preparation, packaging and exposure. A bulk-drug experiment cannot answer that question. Do not treat a general reassurance as permission to disregard FDA’s current patient advice.
For mixing powders once you are satisfied the vial is sound, see how to reconstitute peptides. For the wider safety picture, see are peptides safe.