Compounded semaglutide: is it legal, what to check, and the units math

Compounded semaglutide is the same molecule as semaglutide in Wegovy and Ozempic, made by a pharmacy instead of by Novo Nordisk and sold in a multi-dose vial instead of a pen. Today it is legal only in a narrow patient-specific exception. For almost three years it was widely available because the brand was on the FDA’s shortage list. That window closed in spring 2025, and the FDA spent 2026 tightening enforcement. If you already have a vial, the arithmetic further down matters more than anything else here.

Is compounded semaglutide legal?

Only for an individual patient with a documented clinical need, and not as a routine copy of the approved drug. The FDA’s position, in short:

Neither kind of compounder makes an FDA-approved drug. The FDA says compounded drugs are not reviewed for safety, effectiveness or quality before they are marketed, and that they “should only be used in patients whose medical needs cannot be met by an FDA-approved drug.”

What a 503A pharmacy may still do

A 503A pharmacy may not compound “essentially copies” of a commercially available drug “regularly or in inordinate amounts.” The FDA’s April 2026 update spells out the test. A compounded product is essentially a copy when it has the same active ingredient in the same, similar or easily substitutable strength, and the approved product can be used by the same route. The exception is when a prescriber documents a “significant difference” for an identified patient. The FDA does not intend to act on the copies rule against a pharmacy that fills four or fewer such prescriptions in a calendar month.

Adding an ingredient does not automatically create a difference. The FDA’s example: semaglutide combined with vitamin B12 (cyanocobalamin) may still be essentially a copy if both are injected and the amounts are “within 10% of the strengths” of the approved products.

What a 503B facility may do

Almost nothing, for now. An outsourcing facility may compound from a bulk substance only if the substance is on the 503B bulks list or the drug is on the shortage list. The FDA states: “Tirzepatide and semaglutide do not currently appear on the 503B bulks list or on FDA’s drug shortage list.”

How the shortage ended

The February 2025 order found Novo’s supply “meeting or exceeding demand.” It also acknowledged that “a substantial amount of semaglutide compounding is occurring.” The grace periods existed so that patients on compounded product could move to the approved one.

FDA enforcement through 2026

The agency’s posture has hardened steadily since the deadlines passed.

As of November 2, 2026, we found no final FDA decision on the 503B bulks list proposal. The FDA’s page on unapproved GLP-1s, updated October 1, 2026, also lists a green-list import alert (66-80) that blocks GLP-1 ingredients with potential quality concerns.

What the telehealth letters target is marketing. The FDA has said companies may not call compounded products generic, the same as the approved drug, made with the same active ingredient, or clinically proven.

What are the risks of compounded semaglutide?

Dosing errors are the best documented risk, and the list also includes sterility, fraud and missing trial data. The FDA says it had received 990 adverse event reports tied to compounded semaglutide as of May 31, 2026. It adds that the true count is likely higher, because state-licensed pharmacies that are not outsourcing facilities do not have to report.

• Overdose from unit mix-ups. See the next section.
• Doses beyond the label. The FDA has received reports tied to patients prescribed compounded semaglutide in larger doses, more often, or stepped up faster than the approved label allows.
• Sterility. A multi-dose vial is punctured again and again. The FDA’s advice is a new sterile needle and syringe for every dose, and discarding the vial within 28 days of first use.
• Fraud. The FDA says it is aware of fraudulent compounded products: “In some cases, the compounding pharmacies identified on the labels of the products do not exist.” Other labels name a licensed pharmacy that did not make the product.
• The wrong ingredient. See salt forms, below.
• No trial evidence. The STEP and SELECT results come from the approved products, and the compounded version borrows them.

Products sold online “for research purposes” or as “not for human consumption” are a separate category, and they are not legal to use on people. The FDA has warned sellers of these products, says their quality is unknown, and urges consumers not to purchase them.

Dosing errors: why the units matter

In July 2024 the FDA alerted prescribers, compounders and patients to overdoses with compounded semaglutide. Most reports involved patients who gave themselves “five to 20 times more than the intended dose.” Some needed hospital care. Reported symptoms included nausea, vomiting, abdominal pain, fainting, headache, migraine, dehydration, acute pancreatitis and gallstones.

The FDA tied the errors to confusion between milliliters, milligrams and “units,” and to vials that come in more than one concentration. Its examples:

• A patient told to draw 5 units (0.05 mL) on a U-100 syringe drew 50 units instead, ten times the dose.
• A prescriber meant 0.25 mg, which was 5 units, and wrote 25 units, five times the dose.
• Another prescriber wrote 20 units instead of 2, a tenfold error.

Compared with the pen, the risk is built in. A Wegovy single-dose pen delivers one fixed dose. A vial makes you measure every dose yourself.

How compounded vials are labeled

Three numbers on three different scales are where the errors start. The vial is labeled in milligrams per milliliter. Your prescription is in milligrams. The syringe is marked in units, where 100 units equal 1 mL. A label that lists only a total (“10 mg”) without the volume does not tell you the concentration.

What to check on the vial label

1. Active ingredient, as written. “Semaglutide” is the approved molecule; “semaglutide sodium” or “semaglutide acetate” is not.
2. Concentration in mg/mL, and any additive with its own concentration (for example “5/0.5 mg/mL” for semaglutide with B12).
3. Beyond-use date. Whatever the label says, the FDA advises discarding a multi-dose vial within 28 days of first use, even if medication remains.
4. Pharmacy name, address and license, so the source can be checked. The FDA has seen labels naming pharmacies that do not exist.
5. Storage instructions and a lot number. The FDA advises against using an injectable GLP-1 that arrives warm or poorly refrigerated.

If any of these are missing, call the dispensing pharmacy before use.

Salt forms: a different ingredient

The approved products contain semaglutide base. The FDA says it is aware of compounders using salt forms, semaglutide sodium and semaglutide acetate. It says it has no information showing these match the approved active ingredient, and that it is “not aware of any lawful basis for their use in compounding.” A vial labeled with either salt is not the molecule that was studied in the STEP trials.

How many units is a dose of compounded semaglutide?

Divide the dose in mg by the concentration in mg/mL, then multiply by 100. At 5 mg/mL, 0.25 mg is 5 units. The doses below are the steps on the Wegovy label; the semaglutide dosage chart has every schedule, and the prescriber sets which step applies.

At 5 mg/mL, the starting dose is 5 units, a small mark on a 100-unit syringe. The FDA recommends that prescribers and compounders supply a syringe sized for the dose and show patients how to measure it. The calculator below does the arithmetic for any concentration; the mg/mL to units converter handles other drugs.

How it compares with the brand

Price was the original reason to go compounded, and that gap has narrowed. Novo’s self-pay Wegovy pill starts at $149 a month and the pen is $349. The cheapest GLP-1 without insurance guide lays out every route.

Who should not use it, and what to watch for

Every contraindication on the brand label applies to the compounded version, because it is the same molecule: no use with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2, and none after a serious allergic reaction to semaglutide. The red-flag symptoms are the same too, and the semaglutide side effects guide lists them. If you may have injected too much, the Wegovy label’s advice applies: an overdose can cause severe nausea, severe vomiting and severe low blood sugar, and Poison Help is at 1-800-222-1222. At 5 mg/mL, drawing 50 units instead of 5 delivers 2.5 mg, ten times the starting dose. For technique, the injection sites guide covers where the shot goes.