Brand-name vs. compounded GLP-1s: what’s the difference?

When brand-name GLP-1 medicines were in short supply, many people turned to compounded semaglutide and tirzepatide, often sold through online clinics. Those shortages are over, and the rules for compounded versions have tightened [1, 4].

This article explains what compounding is and how compounded GLP-1s differ from brand-name medicines like semaglutide (Wegovy) and tirzepatide (Zepbound). It also covers what has changed and the warning signs the US Food and Drug Administration (FDA) tells people to look for.

What compounding is

Compounding is when a licensed pharmacist or physician combines, mixes or changes the ingredients of a drug to make a medicine tailored to one patient’s needs. In larger facilities called outsourcing facilities, this is done under a licensed pharmacist’s supervision [1].

Compounded drugs are not FDA approved. That means FDA doesn’t review their safety, effectiveness or quality before they’re sold [1, 2]. They’re also not the same as generic drugs, which are FDA approved [2].

Compounding can meet a real need. FDA gives examples like a person who is allergic to a dye in a medicine, or an older adult or a child who can’t swallow a tablet and needs a liquid [2]. But FDA says compounded drugs should only be used when a patient’s medical needs can’t be met by an FDA-approved drug [2, 3].

There are two main kinds of compounders. State-licensed pharmacies are mostly overseen by state boards of pharmacy. Outsourcing facilities register with FDA, are inspected by FDA on a schedule based on risk, and must meet higher quality standards [2].

How brand-name and compounded GLP-1s compare

	Brand-name (for example, Wegovy or Zepbound)	Compounded semaglutide or tirzepatide
FDA review before it’s sold	Yes: reviewed for safety, effectiveness and quality [3]	No [1, 3]
Strength and dose	Standard strengths, with doses in milligrams (mg) [5, 11, 12]	Strengths can vary from one compounder to another, and instructions may give doses in “units” [5]
How it comes	Pens, vials or pills, with an FDA-approved label and a Medication Guide [11, 12]	Various containers, including multi-dose vials and prefilled syringes [5]

Why compounded versions became so common

Semaglutide and tirzepatide injections were in short supply from 2022 because demand rose so fast. While a drug is on FDA’s shortage list, the law gives compounders more room to make versions that copy it [4].

FDA declared the tirzepatide shortage over on October 2, 2024, and confirmed it after a second review on December 19, 2024. It declared the semaglutide shortage over on February 21, 2025. FDA then gave compounders time to wind down, and the last of those grace periods ended on May 22, 2025 [4].

A group of compounders challenged both decisions in court. On August 27, 2026, the US Court of Appeals for the Fifth Circuit upheld FDA’s decisions [8, 9].

What the rules say now

With the shortages over, compounding pharmacies can’t regularly make, or make large amounts of, versions that are “essentially copies” of FDA-approved drugs. FDA counts a compounded drug as essentially a copy when it has the same active ingredient at the same, a similar or an easily substituted strength, and can be used the same way. The exception is when a prescriber documents that a change makes a significant difference for a specific patient [4].

Adding another ingredient doesn’t automatically make a product different. FDA says, for example, that semaglutide combined with vitamin B12 may still count as a copy [4].

Outsourcing facilities can’t compound these medicines from bulk semaglutide or tirzepatide. Neither is on FDA’s list of bulk ingredients with a clinical need, or on its shortage list [4]. In April 2026, FDA proposed formally excluding semaglutide, tirzepatide and liraglutide from that list [7].

FDA has also acted against misleading marketing. In March 2026, it sent warning letters to 30 telehealth companies over false or misleading claims about compounded GLP-1s. The main problems included implying the products were the same as FDA-approved drugs and hiding who actually made them [6].

Some products sold online can’t legally be compounded at all. Retatrutide and cagrilintide aren’t part of any FDA-approved drug, can’t be used in compounding under federal law and haven’t been found safe and effective for any condition [3]. FDA has also warned companies selling semaglutide, tirzepatide and similar drugs labeled “for research purposes” or “not for human consumption” to people who then use them [3].

Safety problems FDA has reported

• Dosing errors. FDA has received reports of overdoses with compounded semaglutide, some needing hospital care. Many people were measuring doses from multi-dose vials and mixed up milliliters, milligrams and “units”. Some took 5 to 20 times the intended dose. Reported problems included nausea, vomiting, stomach pain, fainting, headache, migraine, dehydration, inflammation of the pancreas (pancreatitis) and gallstones [5].
• Doses beyond the label. FDA has had reports of side effects, some serious, in people given compounded semaglutide or tirzepatide in larger doses, more often or with faster increases than the FDA-approved labels allow [3].
• Different ingredients. Some compounders have used salt forms, such as semaglutide sodium and semaglutide acetate. These are different active ingredients from the one in approved medicines, and FDA says it isn’t aware of any lawful basis for compounding with them [3].
• Fake products. FDA knows of fraudulent compounded semaglutide and tirzepatide with false labels, sometimes naming pharmacies that don’t exist [3].
• Storage. Injectable GLP-1s need to be kept in the fridge. FDA has had complaints of compounded products arriving warm and advises not using any injectable GLP-1 that does [3].
• Multi-dose vials. FDA advises throwing a multi-dose vial away 28 days after you first use it, even if medicine is left, and using a new needle and syringe for every dose [3].

As of May 31, 2026, FDA had received 990 reports of side effects linked to compounded semaglutide and more than 730 linked to compounded tirzepatide. A report doesn’t always mean the medicine caused the problem. But pharmacies that aren’t outsourcing facilities don’t have to report side effects to FDA, so FDA says problems are likely underreported [3].

FDA’s warning signs when buying online

FDA says to watch out for a company that [3]:

• claims a compounded drug is the same as an FDA-approved drug
• offers deep discounts or prices that seem too good to be true
• sends medicine that looks different from what you’ve had before or what was pictured, or that arrives with broken or damaged packaging or no instructions
• doesn’t require a screening and a prescription from a licensed doctor
• doesn’t have a licensed doctor available to answer questions after your medicine arrives
• has spelling errors on the label or gives wrong pharmacy addresses
• puts a pharmacy name on the label that you think might be fake

FDA urges people to buy medicines online only from state-licensed pharmacies [3]. Its BeSafeRx campaign explains how to check a pharmacy’s license [10].

Where brand-name medicines fit in

Brand-name GLP-1s go through FDA’s review for safety, effectiveness and quality before they’re sold [3]. They come in standard doses, with an FDA-approved label and a Medication Guide that explains their risks [11, 12]. Like all medicines, they can cause side effects, so read about GLP-1 side effects too.

If cost is your concern, the makers now sell brand-name GLP-1s directly at self-pay prices posted on their websites [13, 14]. Our article on what GLP-1 medicines cost lists them.

If you take a compounded GLP-1 now

Don’t change your dose or switch on your own. Compounded products come in different strengths, and some give doses in “units”, so a compounded dose may not match a brand-name dose directly [5]. Talk with your clinician about whether and how to switch. It helps to bring your vial or its label, which shows the strength.

If you have a side effect, or a problem with a product’s quality, you or your clinician can report it to FDA’s MedWatch program [3].

When to get medical care

• Call 911 for chest pain, trouble breathing or swallowing, or swelling of your face, lips, tongue or throat [11, 12].
• Get care right away for severe pain in your stomach area that won’t go away, with or without nausea or vomiting. It can be a sign of pancreatitis, and the pain may spread to your back [11, 12].
• Call your clinician the same day if vomiting or diarrhea means you can’t keep fluids down. Losing fluids can lead to kidney problems [11, 12].
• If you think you took too much, contact your clinician right away or get same-day care. An overdose can cause severe nausea, severe vomiting and very low blood sugar, and because semaglutide stays in the body for about a week, you may need to be watched for a while [5].

The bottom line

Compounded GLP-1s aren’t FDA approved, and FDA has reported dosing errors, fake products and other problems with them. Now that the shortages are over, compounders face tight limits on copying brand-name GLP-1s, and FDA has warned companies that market them in misleading ways. If you take a compounded GLP-1 today, talk with your clinician before changing anything. If cost is the issue, compare the makers’ published self-pay prices too.

References

1. US Food and Drug Administration. Human drug compounding. FDA. 2026. https://www.fda.gov/drugs/guidance-compliance-regulatory-information/human-drug-compounding
2. US Food and Drug Administration. Compounding and the FDA: questions and answers. FDA. 2025. https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers
3. US Food and Drug Administration. FDA’s concerns with unapproved GLP-1 drugs used for weight loss. FDA. 2026. https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss
4. US Food and Drug Administration. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize. FDA. Updated April 1, 2026. https://www.fda.gov/drugs/drug-alerts-and-statements/fda-clarifies-policies-compounders-national-glp-1-supply-begins-stabilize
5. US Food and Drug Administration. FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products. FDA. 2024. https://www.fda.gov/drugs/human-drug-compounding/fda-alerts-health-care-providers-compounders-and-patients-dosing-errors-associated-compounded
6. US Food and Drug Administration. FDA warns 30 telehealth companies against illegal marketing of compounded GLP-1s (press release). FDA. 2026. https://www.fda.gov/news-events/press-announcements/fda-warns-30-telehealth-companies-against-illegal-marketing-compounded-glp-1s
7. US Food and Drug Administration. FDA proposes to exclude semaglutide, tirzepatide and liraglutide from 503B bulks list (press release). FDA. 2026. https://www.fda.gov/news-events/press-announcements/fda-proposes-exclude-semaglutide-tirzepatide-and-liraglutide-503b-bulks-list
8. US Court of Appeals for the Fifth Circuit. Outsourcing Facilities Association v. Food & Drug Administration, No. 25-10758 (semaglutide). Fifth Circuit opinion. 2026. https://www.ca5.uscourts.gov/opinions/unpub/25/25-10758.0.pdf
9. US Court of Appeals for the Fifth Circuit. Outsourcing Facilities Association v. Food & Drug Administration, No. 25-10600 (tirzepatide). Fifth Circuit opinion. 2026. https://www.ca5.uscourts.gov/opinions/unpub/25/25-10600.0.pdf
10. US Food and Drug Administration. BeSafeRx: your source for online pharmacy information. FDA. 2020. https://www.fda.gov/drugs/buying-using-medicine-safely/besaferx-your-source-online-pharmacy-information
11. Novo Nordisk. WEGOVY (semaglutide) injection and tablets: prescribing information and Medication Guide. DailyMed, US National Library of Medicine. Label revised June 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b
12. Eli Lilly and Company. ZEPBOUND (tirzepatide) injection: prescribing information and Medication Guide. DailyMed, US National Library of Medicine. Label revised August 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=487cd7e7-434c-4925-99fa-aa80b1cc776b
13. Eli Lilly and Company. Zepbound (tirzepatide). LillyDirect. Accessed October 18, 2026. https://www.lilly.com/lillydirect/zepbound
14. Novo Nordisk. NovoCare Pharmacy. NovoCare. Accessed October 18, 2026. https://www.novocare.com/pharmacy.html

This article is for education only and isn’t a substitute for advice from your own clinician.