How Many Milligrams Are Actually in a Compounded Semaglutide or Tirzepatide Vial?
Four pharmacies sell something called a 5 mg semaglutide vial. Depending on which one you pick, it arrives as a 1 mL vial, a 2 mL vial, or a 5 mL vial, five times the liquid of the first.
Every one of them holds exactly 5 mg of semaglutide.
That is not a trick. It is the single most useful fact about compounded GLP-1 vials, and almost nobody explains it before you buy. The liquid in the vial is mostly not the drug. How much drug is in it depends on a third number, the concentration, and once you can read that number the rest of the label stops being confusing.
Educational information, not a substitute for personalized medical advice. Nothing here tells you what dose to take or how much to draw. Your prescription label and your prescriber decide that.
One thing to be clear about up front: compounded semaglutide and tirzepatide are not FDA approved. Compounded drugs do not go through FDA review for safety, effectiveness, or quality before they are sold, and the FDA's position is that they should be used only in patients whose medical needs cannot be met by an FDA-approved drug. Source: FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss
The one equation
Every question on this page comes back to one line of arithmetic.
milligrams = concentration x milliliters
Three numbers, and any two of them give you the third:
- Milligrams (mg) is the amount of active drug. This is the medicine. This is what a prescription is written in.
- Milliliters (mL) is the amount of liquid. This is the volume of the vial, and it is mostly water, buffer, and preservative.
- Milligrams per milliliter (mg/mL) is the concentration, the amount of drug packed into each milliliter of that liquid. It is the bridge between the other two.
So a 1 mL vial at 5 mg/mL and a 5 mL vial at 1 mg/mL both hold 5 mg. The second one is five times the liquid and the same medicine.
Read the equation the other way and it explains the thing patients actually notice, which is that the amount you draw into the syringe changes depending on which vial you were sent, even when the prescribed milligrams did not change.
The same vial size, three different vials
This is not hypothetical. Here is compounded semaglutide in Temi's catalog, at one nominal vial size, as of August 2026. Four pharmacies sell a 5 mg semaglutide vial, at three different specifications.
| Concentration | Vial volume | Semaglutide in the vial |
|---|---|---|
| 5 mg/mL | 1 mL | 5 mg |
| 2.5 mg/mL | 2 mL | 5 mg |
| 1 mg/mL | 5 mL | 5 mg |
Same headline number. Same 5 mg. Five times the liquid between the top row and the bottom row.
Six compounding pharmacies appear across the whole compounded injectable catalog. Five of them stock semaglutide, at six concentrations from 0.8 mg/mL to 10 mg/mL. All six stock tirzepatide, at six concentrations from 5 mg/mL to 17 mg/mL. Single-vial volumes run from 1 mL to 5 mL for semaglutide and from 0.5 mL to 4 mL for tirzepatide, and single-vial totals run from 0.8 mg to 30 mg and from 5 mg to 68 mg.
Tirzepatide splits the same way.
| Tirzepatide in the vial | Concentration | Vial volume |
|---|---|---|
| 8.5 mg | 17 mg/mL | 0.5 mL |
| 8.5 mg | 8.5 mg/mL | 1 mL |
| 17 mg | 17 mg/mL | 1 mL |
| 17 mg | 8.5 mg/mL | 2 mL |
Look at rows two and three. A 1 mL vial holds 8.5 mg at one pharmacy and 17 mg at another. The vial is the same size. The medicine in it is double.
And it is not only a between-pharmacy problem. One pharmacy in this catalog sells the same 15 mg semaglutide total two ways, as 5 mg/mL in 3 mL and as 10 mg/mL in 1.5 mL. The FDA flagged exactly this pattern, noting that product concentrations vary by compounder and that a single compounder may offer multiple concentrations of compounded semaglutide. Source: FDA alert on dosing errors with compounded injectable semaglutide
Sometimes the field does converge. Every pharmacy in the catalog that sells a 34 mg or a 68 mg tirzepatide vial sells it at 17 mg/mL. Four pharmacies, one specification, no ambiguity. That is the exception, not the rule, and you cannot assume it.
A bigger vial is not more medicine
This is the practical version of the equation, and it is worth stating plainly because the instinct runs the other way.
A vial that holds more liquid is not a bigger supply. A vial that holds more milligrams is. Those two things come apart constantly in this catalog, because volume is a packaging decision and milligrams are the medicine.
Two consequences follow.
Comparing prices on vial size does not work. A 5 mL vial is not "more" than a 1 mL vial in any sense you would pay for. If both hold 5 mg, they are the same purchase in different glass. The comparable number is the total milligrams, and the comparable price is the price per milligram.
Comparing volumes between vials does not work either. If the last vial was 2.5 mg/mL and the new one is 5 mg/mL, the volume that used to hold your prescribed milligrams now holds twice that amount. Nothing about the vial announces this. The label states it, and that is the only place it is stated.
There is a separate reason not to buy the largest vial you can find, which is that the in-use window after first puncture is short: the standard is 28 days from first entry unless the manufacturer specifies otherwise. Source: CDC injection safety guidance for health care providers. Medication beyond that window is medication you discard, so the right vial is the smallest one that covers the window at your prescribed dose.
What "units" means on an insulin syringe
Here is where the arithmetic turns dangerous, and it is worth slowing down.
Compounded vials are usually drawn with a U-100 insulin syringe, because insulin syringes are cheap, finely graduated, and good at small volumes. But an insulin syringe is marked in units, and a unit is not an amount of drug. It is a volume marking. On a U-100 syringe, 100 units is 1 mL, so:
1 unit = 0.01 mL
That is a volume, and volume only. The same 20 units on the same syringe is a different number of milligrams from every different vial concentration, because milligrams still equal concentration times milliliters.
Here is the arithmetic, with 1 mg of semaglutide held constant and the vial concentration changing. Every concentration below is one Temi stocks.
| Vial concentration | Volume holding 1 mg | On a U-100 syringe |
|---|---|---|
| 10 mg/mL | 0.1 mL | 10 units |
| 5 mg/mL | 0.2 mL | 20 units |
| 2.5 mg/mL | 0.4 mL | 40 units |
| 1 mg/mL | 1 mL | 100 units |
Same milligrams, four different marks on the syringe, a tenfold spread from top to bottom. This is arithmetic, not a dosing recommendation. It is here so you can see why a number carried over from a previous vial, a friend, or a forum post is meaningless without the concentration attached to it.
The FDA has documented what happens when this goes wrong. It received reports of adverse events, some requiring hospitalization, from dosing errors with compounded injectable semaglutide, driven by unfamiliarity with drawing from a vial and by confusion between milliliters, milligrams, and "units." In the majority of those reports, patients drew five to twenty times more than the intended amount. In several, patients directed to administer a 5-unit (0.05 mL) dose administered 50 units instead. Prescribers made the same class of error, miscalculating milligram-to-unit conversions so that patients administered five to ten times the intended amount.
Two rules follow, and they are the only dosing guidance in this article:
- The volume to draw comes from your prescription label, for the vial in your hand. Not from a calculator, not from a previous vial, not from the internet.
- If the label is unclear, or the new vial does not look like the last one, ask before you draw. The FDA's own recommendation is that patients talk with their provider or compounder about how to measure and administer the intended dose.
Tirzepatide makes the same point with numbers that do not come out round. Hold 5 mg constant and three of the catalog's concentrations give three different volumes: 0.5 mL from a 10 mg/mL vial, 0.625 mL from an 8 mg/mL vial, and about 0.294 mL from a 17 mg/mL vial. Only the first lands on a whole unit mark. That is one more reason to read the volume off the label rather than dividing it out yourself.
Why Temi lists the total milligrams
Temi's catalog is built on the number that compares, which is the total active ingredient in the package.
On the compounded semaglutide and compounded tirzepatide pages, each offer card in the pharmacy picker leads with the vial price, then prints the vial in milligrams and the price per milligram. Price per milligram is there specifically so that two vials of different volumes from different pharmacies can be read against each other in a second, without any arithmetic on your part.
Below the picker, the product details table for whichever offer you have selected spells out the rest of the label: the active ingredient, the total milligrams, the concentration, the vial volume, the additives, the beyond-use date, and the 28-day in-use window after puncture. Those numbers come from the pharmacy that would fill your prescription, not from a generic template, and they change when you select a different pharmacy. That is the point of showing them.
What the catalog deliberately does not do is convert any of it into a volume for you. A displayed volume would be a dose, a dose is a clinical decision, and the clinical decision belongs to the physician who reviews your history and to the label that ships with your vial.
FAQ
How many mg are in a semaglutide vial?
It depends entirely on the vial, and the volume does not tell you. Across Temi's catalog, a single compounded semaglutide vial holds anywhere from 0.8 mg to 30 mg. The total milligrams are printed on the label and listed in the product details for every offer. If you only know the vial is "1 mL," you do not yet know how much semaglutide is in it.
How do I convert semaglutide units to mg?
Units are a volume marking on the syringe, not an amount of drug, so there is no fixed conversion. On a U-100 insulin syringe, 100 units is 1 mL and 1 unit is 0.01 mL. To get milligrams you also need the vial's concentration: milligrams equals units divided by 100, times the mg/mL on the label. Twenty units is 0.2 mL, which is 1 mg from a 5 mg/mL vial and 0.5 mg from a 2.5 mg/mL vial. Use this to understand the label, not to set a dose.
I have a 2.5 mg/mL semaglutide vial. How much do I draw?
The volume printed on your prescription label, which was written for that vial. The arithmetic behind it is milliliters equals milligrams divided by 2.5, so 1 mg would be 0.4 mL and 0.5 mg would be 0.2 mL. That is the math, not a recommendation. Do not calculate your own dose, and ask your care team if the label and the vial do not match.
Is a 5 mL vial more medicine than a 1 mL vial?
Not necessarily. A 5 mL vial at 1 mg/mL and a 1 mL vial at 5 mg/mL both hold 5 mg. Both of those are real listings in this catalog. Compare the total milligrams, never the volume.
Why does my new vial look different from the last one?
Most likely a different pharmacy, a different concentration, or both. There is no standard compounded formula: each 503A pharmacy sets its own concentration, vial volumes, inactive ingredients, and beyond-use dating. A change in the liquid level, the vial size, or the additive line does not mean the prescription changed. Read the new label rather than repeating the volume from the old vial.
Does a higher concentration mean a stronger dose?
No. Concentration describes the vial, not the prescription. A higher concentration means the same milligrams sit in less liquid, so you draw a smaller volume for the same amount of drug. The dose is set by your prescriber and stated on the label.
Do the additives change any of this math?
No. The additive line, whether it reads B12, glycine, or no additive at all, is a separate ingredient from the GLP-1 and does not change the milligrams of semaglutide or tirzepatide in the vial. We cover what those additives are and are not in a separate article.
Is compounded semaglutide or tirzepatide FDA approved?
No. Compounded preparations do not undergo FDA premarket review for safety, effectiveness, or quality, and the FDA's position is that they are for patients whose medical needs cannot be met by an FDA-approved drug.
Key takeaways
- Milligrams equal concentration times milliliters. Any two of the three numbers give you the third, and every confusion on a compounded label dissolves once you have all three.
- Vial volume is packaging. Milligrams are medicine. A 5 mL vial and a 1 mL vial can hold exactly the same 5 mg, and in this catalog they do.
- The same nominal vial size is not the same product. Four pharmacies sell a 5 mg semaglutide vial at three different concentrations, and a 1 mL tirzepatide vial holds 8.5 mg at one pharmacy and 17 mg at another.
- A unit is a volume, not a dose. On a U-100 syringe 1 unit is 0.01 mL, so the milligrams behind 20 units change with every concentration.
- The FDA has documented hospitalizations from exactly this confusion, with most reported patients drawing five to twenty times the intended amount.
- Your label is the only authority on what to draw, for the specific vial in your hand. Never carry a volume over from a previous vial.
- Compounded GLP-1s are not FDA approved, and the FDA's position is that they are for patients whose medical needs cannot be met by an approved drug.
This article reflects Temi catalog data as of August 2026 and public FDA and CDC material as of the same date. Catalog concentrations and vial volumes change. It is not medical advice, it does not tell you what to take or how much to draw, and it does not replace a conversation with your own clinician.
References
- U.S. Food and Drug Administration. FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products. Link
- U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Link
- U.S. Food and Drug Administration. Pharmacy Compounding of Human Drug Products Under Section 503A of the Federal Food, Drug, and Cosmetic Act: Guidance. PDF
- Centers for Disease Control and Prevention. Injection safety: clinical safety considerations for health care providers. Link
- Temi. Compounded semaglutide injectable.
- Temi. Compounded tirzepatide injectable.
- Temi. What is actually in a compounded semaglutide or tirzepatide vial?
- Temi. How Temi works.
- Temi. Online GLP-1 intake.
If you want to see the concentration and vial volume behind every price, the compounded semaglutide and compounded tirzepatide pages list both for every pharmacy Temi can reach in your state. When you are ready for a clinician to review whether treatment fits your history, you can start the online intake. Submitting it starts a review; it is not a guarantee that anything will be prescribed.
Temi is making access to healthcare more seamless. Not sure what the numbers on your vial mean? Your Temi care team is here to help. usetemi.com