Read This First
This page is not built on clinical evidence. It is built on the approved product's label, the FDA's compounding rules and enforcement record, and the manufacturer's litigation. What tirzepatide does in people is covered on the library entry; this page is about the difference between the approved product and everything else sold under its name, and about how that difference changed in 2025.
For two years, compounded tirzepatide was a lawful product made at scale. Since 19 December 2024 it has not been. The FDA declared the shortage resolved on that date, enforcement discretion ended in February and March 2025, and what remains is an approved drug with several presentations, a shrinking compounded market operating at the edge of the rules or beyond them, a research-vial market that was never lawful, and a regulator that had logged more than 730 adverse event reports for compounded tirzepatide by 31 May 2026.12
The Approved Product
What Is It?
Tirzepatide as Mounjaro or Zepbound, in four presentations as of the August 2026 label: single-dose prefilled pens, single-dose vials, multi-dose vials holding four weekly doses, and a single-patient-use KwikPen holding four weekly doses, added in January 2026. Every presentation comes in the six strengths from 2.5 to 15 mg.3 The vials and the KwikPen are how Lilly moved the drug into cash-pay and government channels; the sourcing consequence is that "tirzepatide in a vial" is no longer a sign of a compounded or gray-market product. It can be the approved one.
What Does "Approved" Guarantee?
Identity, content, sterility, endotoxin limits, stability through the labelled shelf life under the labelled storage, a validated manufacturing process, and a label with a boxed warning, contraindications and a dose-escalation schedule. Those are the things a certificate of analysis on a compounded or research vial is trying to imitate.
Compounded Tirzepatide
Is It Legal?
Rarely, now. The rule is the same one that governs any compound with an approved product: pharmacies may compound a copy of a commercially available drug only where a prescriber documents a change that produces a significant difference for the individual patient, and they may not do so "regularly or in inordinate amounts."4 During a shortage that rule is suspended, which is how the compounded market grew from 2022. The FDA ended the tirzepatide shortage by declaratory order on 19 December 2024; it declined to enforce until 18 February 2025 for 503A pharmacies and 19 March 2025 for 503B outsourcing facilities, courts denied injunctions against both dates, and the agency's position since is that "when a drug shortage is resolved, FDA generally considers the drug to be commercially available."1
What survives is narrow. A pharmacy may still fill four or fewer prescriptions a month for an essentially identical copy under current enforcement policy, and may compound a genuinely different product for a documented patient need.1 A telehealth service dispensing compounded tirzepatide by the thousand is doing neither.
What Happened to the Compounders?
Two things, in parallel. Lilly sued. In April 2025 it filed against compounding pharmacies and then against telehealth companies selling compounded tirzepatide, stating that it "cannot validate the safety or effectiveness of products claiming to contain tirzepatide" that are not its own.5 And the FDA issued warning letters: a wave in September 2025, and a second wave of 30 announced on 3 March 2026, citing two violations above all, "claims implying sameness with FDA-approved products" and "obscuring product sourcing" by branding a compounded product with the telehealth firm's own name as if it were the manufacturer.6
The second violation is the sourcing point. A product labelled with a telehealth brand is not made by the telehealth brand. It is made by a pharmacy the brand may not name, from active ingredient the pharmacy sourced, under conditions neither will show the buyer.
The "Personalised Dose" Products
After the shortage ended, some compounders and telehealth services began offering tirzepatide at strengths not in the approved range, or with added vitamins, to argue that the product was not a copy. The FDA's guidance anticipates this: a change made "for an identified individual patient" that "will produce a significant difference for that patient" is the test, and a change made to every patient's product in order to keep selling it is not that.4 The FDA's adverse event page also records what non-standard strengths have produced: patients dosed "beyond what is in the FDA-approved drug label" needing medical attention for nausea, vomiting, diarrhoea, abdominal pain and constipation.2
What Should a Compounded Product Come With?
A prescription from a named prescriber, and a stated, patient-specific reason the approved product is not being used
The compounding pharmacy's own name, licence state, lot number and beyond-use date on the label, not a telehealth brand
A stated strength per millilitre and a dosing schedule that matches the approved escalation, since the escalation exists to prevent the gastrointestinal events the FDA has logged
Refrigerated shipping, and a product that arrives cold
Research-Labelled and Imported Product
What Is Being Sold?
Lyophilised powder, commonly in 10 to 60 mg vials, labelled for research use, from vendors that also sell retatrutide and the peptides elsewhere in this library. Unlike compounded product, this was never lawful for human use and never depended on the shortage. Its active ingredient is imported bulk peptide, and the FDA screens exactly that at the border under import alert 66-80, which subjects GLP-1 active pharmaceutical ingredients to detention without physical examination unless the manufacturer has been evaluated and listed.2
The FDA's description of what such products may contain is general and worth quoting: they "could contain the wrong ingredients or harmful ingredients" and "could contain too little, too much or no active ingredient at all."2
Does "Research Use Only" Change Anything?
No. It is a liability position adopted by the seller, not a regulatory category. In warning letters to peptide sellers the FDA has held that the disclaimer does not survive product copy establishing human use; the same letters cite tirzepatide sold under a research label with weight-loss claims on the same page.7
Purity Testing Versus Identity Testing
| Test | Question it answers | Question it cannot answer |
|---|---|---|
| HPLC purity | What proportion of the sample is one substance | Whether that substance is tirzepatide, a truncated sequence, or a cheaper GLP-1 analogue that also suppresses appetite |
| Mass spectrometry identity | Whether the mass matches tirzepatide, about 4,813 daltons | How much of the sample it represents; whether the fatty-acid side chain that gives the drug its week-long action is intact |
| Endotoxin assay | Whether bacterial cell-wall fragments are present | Identity or content |
| Sterility | Whether viable organisms are present | Anything about the peptide |
The substitution risk is specific to this class. A vial of semaglutide sold as tirzepatide would produce weight loss and nausea, and the buyer's experience would confirm the label. Feeling the drug work is evidence that something active was in the vial. It is not evidence of what.
Certificates of Analysis
A laboratory report on one batch. Read it for the laboratory's independence from the seller, the lot number and whether it matches the vial, the date, and which tests were run. It cannot establish that the vial in hand came from the batch tested; that rests on a chain of custody the buyer cannot inspect. A certificate is a PDF, and the FDA has documented fabricated pharmacy names and labels on gray-market GLP-1 products, which is the setting in which a fabricated certificate would sit.2
Storage and Handling
What the Label Says
This is the one compound in this group of pages with a fully validated specification, and it is more detailed than most buyers know. Single-dose pens and vials are refrigerated at 2 to 8°C and may be kept unrefrigerated at up to 30°C for a total of 21 days. Unopened multi-dose vials and KwikPens are refrigerated until expiry, or discarded after 30 days at room temperature. Once opened, a multi-dose vial or KwikPen is discarded "after a total of 30 days at room temperature, 30 days after first use, or after taking 4 weekly doses, even if there is medicine left in it." Nothing is frozen, and a frozen product is discarded.3
Those figures were generated for those formulations in those containers. They do not transfer to a compounded vial with different excipients or a reconstituted research vial. The FDA's general guidance for compounded multi-dose injectables, discard within 28 days of first use, is the applicable rule for those.2
Cold Chain
The FDA has received complaints of compounded GLP-1 products arriving warm or with inadequate ice packs, and advises not to use any injectable GLP-1 that arrives warm or insufficiently refrigerated.2 A warm package is one of the few quality failures a buyer can observe.
Signs to Stop Rather Than Proceed
A product that arrives warm when cold shipping was promised
A label carrying a telehealth brand rather than a pharmacy name, or a pharmacy name that cannot be found in a state licence register
A strength or schedule that does not correspond to the approved 2.5 mg steps, offered to every customer rather than justified for one
Severe or persistent vomiting, abdominal pain or dehydration, which the label treats as reasons to seek care and which the FDA has logged from non-standard compounded doses3
Any of the FDA's telehealth warning signs: deep discounts, no screening or prescription, no clinician available afterwards, label spelling errors, or a pharmacy name that looks fabricated2
Community Language
Tirzepatide, Mounjaro, Zepbound
The molecule and its two brand names. Same drug; different labels.
Vials
Since 2024, an approved presentation as well as a compounded one. The label on the vial, not the vial itself, says which.
KwikPen
The multi-dose pen approved in January 2026, holding four weekly doses. The presentation the Medicare programme covers.3
Compounded tirzepatide
Tirzepatide made by a pharmacy. Lawful at scale only during the shortage, which ended in December 2024.1
Personalised dosing, "tirzepatide plus B12"
Post-shortage product variations offered to argue the product is not a copy. The test is a documented difference for an individual patient, not a formulation change applied to everyone.4
Research use only
A seller's disclaimer. Not a regulatory category, and not a defence the FDA has accepted where the marketing says otherwise.7
Green list
The exemption schedule inside import alert 66-80. Being on it means a manufacturer has been evaluated, not that a given shipment has been tested.2
Related ONPEPS Coverage
Tirzepatide library entry: the trials, the label and what the outcomes data do and do not show
Tirzepatide cost and access: vials, pens, Medicare and the price moves of 2025 and 2026
Compounded, gray market and counterfeit semaglutide: what the regulators have documented
Sources
US Food and Drug Administration. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize. Drug Alerts and Statements. Content current as of 1 April 2026. fda.gov
US Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Drug Alerts and Statements. Content current as of 1 September 2026. fda.gov
Eli Lilly and Company. ZEPBOUND (tirzepatide) injection: prescribing information. Revised August 2026. DailyMed. dailymed.nlm.nih.gov
US Food and Drug Administration. Compounded Drug Products That Are Essentially Copies of a Commercially Available Drug Product Under Section 503A of the Federal Food, Drug, and Cosmetic Act: Guidance for Industry. January 2018. fda.gov
Eli Lilly and Company. Lilly statement on Mounjaro (tirzepatide) compounding litigation. Investor news release. investor.lilly.com
US Food and Drug Administration. FDA warns 30 telehealth companies against illegal marketing of compounded GLP-1s. Press announcement, 3 March 2026. fda.gov
US Food and Drug Administration. Warning Letter: Gram Peptides. MARCS-CMS 721806, 31 March 2026. fda.gov
Not Medical Advice
Tirzepatide is a prescription medicine with a boxed warning and a label that governs its use. If you are using a product obtained outside a pharmacy, or a compounded product whose source you cannot name, the route back to oversight is a clinician who knows what you have taken.
Label and regulatory sources verified 16 September 2026. Compounding enforcement is active and the record changes frequently. Re-verify before relying on any statement here.