Compounded vs Brand GLP-1 Safety: What Patients Need to Know in 2025

What is actually different about a compounded GLP-1?

The approved weight-management GLP-1 products are Wegovy (semaglutide), Saxenda (liraglutide), Zepbound (tirzepatide) and Foundayo (orforglipron) [2][4][3][5]. Each has a label that states its indication, its dose escalation and its warnings [2][5]. Approval also includes a review of the manufacturer's compliance with current good manufacturing practice, the regulations that cover the methods, facilities and controls used to make a drug and that are written to make sure a product is safe for use and has the ingredients and strength it claims [8].

A compounded GLP-1 sits outside that process. FDA states that compounded drugs are not FDA approved, which means the agency does not review them for safety, effectiveness or quality before they are marketed [1]. As of 31 May 2026 FDA had 990 adverse event reports for compounded semaglutide and more than 730 for compounded tirzepatide, and reports of dosing errors [6][1].

FDA's position on when compounding fits is narrow: compounded drugs should only be used in patients whose medical needs cannot be met by an FDA-approved drug [1].

What are the rules for compounding these drugs?

The rules differ by who is doing the compounding.

Outsourcing facilities. An outsourcing facility is restricted in which bulk drug substances it may use: the substance must appear on FDA's list of substances for which there is a clinical need or meet another FDA condition [6]. FDA states that semaglutide and tirzepatide do not currently meet those conditions [6].

State-licensed pharmacies and physicians. The product must be compounded for an individual patient after a prescription is received. The compounder may not compound, regularly or in inordinate amounts, products that are essentially copies of a commercially available drug. FDA may treat a compounded product as an essentially identical copy when it matches a commercially available product in strength and route, unless the prescriber documents a significant difference for that patient [6]. FDA also said it does not intend to take action against a compounder that fills four or fewer prescriptions of such a copy in a calendar month [6].

Separately, on 30 April 2026 FDA proposed to exclude semaglutide, tirzepatide and liraglutide from the bulks list, finding no clinical need for outsourcing facilities to compound them from bulk substances. Comments were due 29 June 2026 and no final decision had been made [7].

Do the published trial results apply to compounded versions?

Trials of the approved products provide measured weight-loss and adverse-event results, but they do not establish what a compounded product will do [2][3][9][10]. In STEP 1, 1,961 adults with obesity or overweight and no diabetes received semaglutide 2.4 mg weekly or placebo for 68 weeks. Mean weight change was −14.9% versus −2.4% [9]. In SURMOUNT-1, 2,539 adults with obesity or overweight and no diabetes received tirzepatide 5, 10 or 15 mg or placebo for 72 weeks. Mean weight change was −15.0%, −19.5% and −20.9% versus −3.1% [10]. We found no published trial comparing a compounded GLP-1 with an approved one on weight, glucose or side effects.

What do the approved labels warn about?

Gastrointestinal effects are the common class effect and are worst during dose escalation [2]. The Wegovy label lists nausea in 44% versus 16% on placebo, diarrhea 30% versus 16%, vomiting 24% versus 6% and constipation 24% versus 11% in adults with obesity or overweight [2]. For Zepbound 15 mg, pooled across trials, the label lists nausea 28% versus 8%, vomiting 13% versus 2%, diarrhea 23% versus 8% and constipation 11% versus 5% [3]. Rates from different trials are not directly comparable [2]. In the Wegovy weight-management trials, 6.8% of patients on 2.4 mg stopped treatment for adverse reactions versus 3.2% on placebo [2].

Wegovy and Zepbound carry boxed warnings based on thyroid C-cell tumors seen in rodents at clinically relevant exposures, and their labels state that the human relevance of those findings is unknown [2][3]. Foundayo also carries a thyroid C-cell tumor boxed warning, but its label says orforglipron did not produce tumors in rodents [5]. All three labels contraindicate use in people with a personal or family history of medullary thyroid carcinoma or MEN 2 [2][3][5]. Other labeled warnings include acute pancreatitis, severe gastrointestinal reactions (with a statement that the drug is not recommended in severe gastroparesis), acute kidney injury from volume depletion, gallbladder disease, hypoglycemia when combined with insulin or a sulfonylurea, serious hypersensitivity, and pulmonary aspiration during general anesthesia or deep sedation [2][5].

A compounded product is not FDA-approved and has not been through that labeling review [1].

What problems are specific to compounded vials?

FDA has described handling problems that come with compounded GLP-1s. Multi-dose vials of sterile medicines should generally be used within 28 days of first use because the risk of contamination rises after that; FDA recommends discarding the vial at 28 days even if medication remains, and using a new sterile needle and syringe for each dose [1].

Injectable GLP-1 drugs require refrigeration. FDA has received complaints that some compounded GLP-1 drugs arrived warm or with inadequate ice packs, and it recommends not using an injectable GLP-1 that arrives warm or insufficiently refrigerated [1].

Can retatrutide or cagrilintide be compounded?

No. FDA states that retatrutide and cagrilintide cannot be used in compounding under federal law, that they are not components of FDA-approved drugs, and that they have not been found safe and effective for any condition [1].