Tirzepatide is a once-weekly injectable peptide from Eli Lilly that activates both the GIP and GLP-1 receptors, and it's FDA-approved as Mounjaro (type 2 diabetes) and Zepbound (weight management and sleep apnea). Vials sold online as "research" tirzepatide are a different product: they aren't made under Lilly's approval, and FDA has warned sellers of them.
Notice: Research peptides are sold for in-vitro laboratory research only. Research-labeled vials are not the approved drug, not for human or animal consumption, and this page is not medical advice. It contains no dosing or use guidance.
How tirzepatide works
Tirzepatide "activates receptors of hormones secreted from the intestine (glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP))," according to FDA's Zepbound announcement. Both hormones are released after eating. Semaglutide acts only on GLP-1, so tirzepatide is often called a "dual agonist." Lilly's investigational retatrutide adds a third receptor, glucagon.
For side-by-side trial data, see semaglutide vs tirzepatide and retatrutide vs tirzepatide.
Approvals
| Date | Product | What FDA approved | Source |
|---|---|---|---|
| May 13, 2022 | Mounjaro | Blood sugar control in adults with type 2 diabetes | Drugs.com history |
| November 8, 2023 | Zepbound | Chronic weight management | FDA |
| December 20, 2024 | Zepbound | Moderate to severe obstructive sleep apnea in adults with obesity | FDA |
| February 23, 2026 | Zepbound | Multi-dose KwikPen added to the label (announcement date) | Lilly |
| August 28, 2026 | Mounjaro | Reducing the risk of major cardiovascular events in adults with type 2 diabetes at high cardiovascular risk | Lilly |
Lilly's August 2026 release also notes that Mounjaro is approved for blood sugar control in children 10 years and older with type 2 diabetes.
What the trials found
Lilly ran two main phase 3 programs: SURPASS in type 2 diabetes and SURMOUNT in obesity. Figures below are the published or company-reported averages for the approved drug. Dose groups are described without amounts.
SURMOUNT-1 (obesity, no diabetes)
2,539 adults, 72 weeks. Mean weight loss was 16.0%, 21.4% and 22.5% across the three dose groups versus 2.4% on placebo, using the efficacy estimand (Lilly, June 4, 2022; NEJM).
SURPASS-2 (type 2 diabetes, vs semaglutide)
1,879 adults, 40 weeks. A1C fell 2.09 to 2.46 points across tirzepatide groups versus 1.86 with injectable semaglutide. Weight change was -8.5% to -13.1% versus -6.7% (Lilly, June 25, 2021).
SURMOUNT-5 (obesity, vs semaglutide)
751 adults without diabetes, 72 weeks, open-label and sponsored by Lilly. Mean weight change was -20.2% with tirzepatide versus -13.7% with semaglutide (Aronne et al., NEJM 2025). Details are in semaglutide vs tirzepatide.
SURPASS-CVOT (cardiovascular outcomes)
13,299 adults with type 2 diabetes and established atherosclerotic cardiovascular disease, compared against dulaglutide (Trulicity), with a median follow-up of about four years. Tirzepatide was non-inferior for major adverse cardiovascular events, about 8% lower (hazard ratio 0.92, 95.3% CI 0.83-1.01). Lilly states: "Superiority to dulaglutide was not established" (Lilly, August 28, 2026).
Side effects
The most common side effects on the Zepbound label are gastrointestinal: nausea, diarrhea, vomiting and constipation. Both tirzepatide products carry a boxed warning about thyroid C-cell tumors seen in rodents (FDA). The prescribing information is the authoritative list.
Shortage, compounding and research labels (October 2026)
- Shortage over. FDA determined the tirzepatide injection shortage was resolved on December 19, 2024. Its enforcement discretion for outsourcing facilities ran to March 19, 2025, and the period for state-licensed pharmacies "has ended" (FDA, content current as of April 1, 2026).
- February 2026 crackdown. On February 6, 2026, FDA said it would take "decisive steps to restrict GLP-1 active pharmaceutical ingredients" used in non-approved compounded drugs (FDA).
- 503B proposal. On April 30, 2026, FDA proposed excluding semaglutide, tirzepatide and liraglutide from the 503B bulks list, finding no clinical need for outsourcing facilities to compound them from bulk (Federal Register; Orrick). Comments closed June 29, 2026. We found no final decision as of October 21, 2026.
- Adverse events. As of May 31, 2026, FDA had received more than 730 adverse event reports for compounded tirzepatide, which it says are likely underreported (FDA, current as of October 1, 2026).
- "Research" labels. The same FDA page says it has warned companies selling GLP-1 drugs "falsely labeled 'for research purposes' or 'not for human consumption.'" FDA's August 24, 2026 letter to Peptide Partners named a product sold as "GLP-2 T (Tirzepatide)," despite research-use labeling.
More: FDA peptide regulation in 2026 and Eli Lilly's peptide lawsuits.
Research-grade vials: what the market looks like
On October 21, 2026, 36 vendors in our price index had tirzepatide in stock, at a median of $5.20 per mg. Many list it under a code name. The cheapest per mg were:
| Vendor | Listing | Price | $/mg |
|---|---|---|---|
| Elite Research USA | GLP(2)TZ Research Peptide 60mg | $159.99 | $2.67 |
| Maximum Peptides | Tirzepatide (listed as GLP-2T) 100mg | $280.00 | $2.80 |
| Drexa Labs | Tirzepatide Research Peptide (Tirz) 100mg | $329.00 | $3.29 |
Prices are as listed on vendors' sites on October 21, 2026, and they change often. The full list is on the tirzepatide price page, and our certificate comparison is at best tirzepatide vendors.
None of the trial results above apply to these vials. They weren't made by Lilly, weren't studied in SURMOUNT or SURPASS, and aren't checked by FDA for identity, purity or sterility.
How to check a tirzepatide COA
- The compound is named as tirzepatide. A certificate for "GLP-2" or "TZ" alone doesn't tell you what was tested.
- Identity by mass spectrometry. Tirzepatide's molecular weight is about 4,813 g/mol. Purity by HPLC can't confirm the molecule.
- Measured content against the label, since large vials make underfills costly (purity vs net content).
- A lot number matching your vial, a recent date and a named lab you can verify.
- Endotoxin and sterility results if the vendor claims them.
Our COA guide and COA checklist go through each step.
Bottom line
Tirzepatide is an approved dual GIP/GLP-1 agonist with a large trial record, sold by prescription as Mounjaro and Zepbound. The shortage that allowed mass compounding ended in December 2024, and FDA has spent 2026 tightening the rules further. Research-labeled tirzepatide is outside all of that: it isn't the approved drug, and FDA has named it in warning letters.
Sources are linked inline and were checked October 21, 2026. We'll update this page when FDA finalizes its 503B decision or approves new indications.
