What You'll Learn
Table of Contents
What Compounding Is, And What It Is Not
Pharmacy compounding is the preparation of a medication by a pharmacist or physician to meet the needs of an individual patient — historically for things like an allergy to a dye in a commercial formulation, or a dose form a manufacturer does not make.
The single most important fact about it is one the FDA states directly: compounded drugs are not FDA approved. The agency does not review them for safety, effectiveness or quality before they are marketed. Its stated position is that compounded drugs should only be used where a patient's medical needs cannot be met by an available FDA-approved drug.
That is a much narrower purpose than the one compounded semaglutide came to serve. Between 2022 and 2025 it was sold at scale, largely through telehealth, as a cheaper substitute for a drug that was in shortage — which is a different thing from meeting an individual medical need.
The approved products are specific: Wegovy and Ozempic as pre-filled pens with preset or standard doses, and Rybelsus as an oral tablet. Everything below follows from what happens when that packaging is replaced by a vial and a syringe.
Bottom line: “Compounded” is not a grade or a tier of the approved drug. It is a separate category that has not been through premarket review for safety, effectiveness or quality. Cheaper is not the only difference.
Five To 20 Times The Intended Dose
The FDA published an adverse event summary for compounded injectable semaglutide. The central finding, in the agency's own words, is that the majority of reports described patients mistakenly drawing up more than the prescribed dose from a multiple-dose vial — and that in these instances patients administered five to 20 times more than the intended dose.
The reported consequences: gastrointestinal effects including nausea, vomiting and abdominal pain, plus fainting, headache, migraine, dehydration, acute pancreatitis and gallstones. Some patients sought medical attention. Some required hospitalisation.
One detail makes an overdose here worse than it would be with most drugs. Semaglutide has a half-life of about a week. The FDA notes that a prolonged period of observation and treatment may be necessary for that reason — you cannot simply wait a few hours for it to clear. Twenty times a dose of something that persists for weeks is not a brief unpleasant episode.
The majority of reports described patients mistakenly drawing up more than the prescribed dose from a multiple-dose vial during self-administration. Reported events included acute pancreatitis and gallstones; some patients required hospitalisation.
Read the FDA alert ↗Important: If you have taken more than your intended dose of any GLP-1 product, this is a matter for immediate medical advice, not for an article. The long half-life means the effect does not pass quickly.
Why The Errors Happen
These were not careless people. The mechanism is structural, and the FDA describes it precisely.
The vial and the syringe
Approved injectable semaglutide comes in pre-filled pens dosed in milligrams at standard concentrations. Compounded semaglutide arrives in multiple-dose vials or prefilled syringes, at concentrations that vary between compounders — and a single compounder may offer several different concentrations.
The word “units”
Instructions for compounded products often specify doses in units, and how much drug a unit represents depends entirely on the concentration. Patients were also given syringes significantly larger than the prescribed volume.
The specific error, from the FDA's report: patients instructed to draw 5 units — 0.05 mL — from a vial using a U-100 1 mL insulin syringe instead drew 50 units. Ten times the dose, from one misreading of a syringe barrel most people have never used before.
The prescribers made the same mistake
This is the part that should end any assumption that care and attention are sufficient protection. The FDA describes health care providers incorrectly converting milligrams to units or millilitres:
- A provider intending 0.25 mg (5 units) prescribed 25 units. Five times the dose; the patient had severe vomiting.
- A provider prescribed 20 units instead of 2, affecting three patients, all of whom received ten times the intended dose.
- A patient who was themselves a health care provider recalculated their own dose and self-administered ten times what was intended.
In one case a patient could not get clear dosing instructions from the telemedicine provider who had prescribed it, searched online for guidance, and took five times the intended dose.
Salt Forms, And Things Added To The Vial
Two further problems, both about what is actually in the product.
Semaglutide sodium and semaglutide acetate
The FDA received reports that some compounders were using salt forms of semaglutide. In the agency's framing these are different active ingredients from the base form used in the approved drugs. The FDA states it does not have information on whether these salts share the same chemical and pharmacologic properties as the approved active ingredient, and that it is not aware of any lawful basis for their use in compounding.
Read that carefully. It is not a claim that the salt forms are dangerous. It is a statement that nobody knows whether they behave the same way — which, for an injectable you are taking weekly for a year, is its own answer.
The additives
The FDA also notes that some compounders incorporate additional ingredients into their semaglutide products: cyanocobalamin (vitamin B12), pyridoxine (vitamin B6), levocarnitine, and NAD. The agency's position is that the safety and effectiveness of combining semaglutide with these has not been established.
B12 in particular is often presented as an energy or side-effect benefit. There is no trial establishing that. If your interest is in micronutrient status on a GLP-1, that is a question for blood work and a clinician, not something to solve by having it mixed into an injection.
Storage
Injectable GLP-1 drugs require refrigeration. The FDA has received complaints of compounded products arriving warm, or with inadequate ice packs, and recommends not using any injectable GLP-1 drug that arrives in that condition.
The Legal Position Changed In 2025
This is the part most online writing on the subject has not caught up with, and it matters more than any of the above.
The lawful basis for compounding these drugs at scale was their presence on the FDA drug shortage list. Semaglutide injection had been in shortage since 2022 due to demand. On 21 February 2025 the FDA determined that shortage resolved, having confirmed with the manufacturer that stated availability and manufacturing capacity could meet present and projected national demand.
What followed, with the enforcement dates the FDA published:
- Tirzepatide, 503A (state-licensed pharmacies and physicians): enforcement discretion ended after the court denied a preliminary injunction on 5 March 2025.
- Tirzepatide, 503B (outsourcing facilities): to 19 March 2025.
- Semaglutide, 503A: enforcement discretion ended following the court's denial of a preliminary injunction on 24 April 2025.
- Semaglutide, 503B: to 22 May 2025.
The FDA also states plainly that tirzepatide and semaglutide do not appear on the 503B bulks list or on the drug shortage list.
So the window closed. Compounded semaglutide sold today as a routine cheaper alternative is not operating under the conditions that made it lawful in 2023. Narrow compounding for a genuine individual need that an approved product cannot meet is a different matter and remains a clinical question for a prescriber.
Fakes, And The Peptides Sold Alongside
Two things the FDA has flagged that are worth knowing before you evaluate any offer you encounter.
Fraudulent labels
The agency is aware of fraudulent compounded semaglutide and tirzepatide carrying false label information. In some cases the compounding pharmacy named on the label does not exist. In others the label names a real licensed pharmacy which, on the FDA's information, did not compound the product. A pharmacy name on a vial is not verification of anything.
The FDA has also established a green list import alert (66-80) targeting GLP-1 active pharmaceutical ingredients with potential quality concerns entering the U.S. supply chain.
Retatrutide and cagrilintide
These names now appear regularly in the same marketplaces. The FDA's position is unambiguous: retatrutide and cagrilintide cannot be used in compounding under federal law, are not components of any FDA-approved drug, and have not been found safe and effective for any condition.
The agency has issued warnings to telehealth companies marketing unapproved drugs including retatrutide directly to consumers, to API distributors selling it to compounders, and to outsourcing facilities repackaging it.
These are genuine investigational compounds in real clinical programmes. That is precisely what makes them attractive to sell and premature to inject — being in trials is what “we do not yet know” looks like from the inside.
If you are comparing the approved options rather than the grey market, four names, two drugs covers what is actually licensed and how the two molecules differ.