Vials & syringes
How many doses are in a vial?
Medically reviewed by Linda West-Conforti, RN · CA RN #389453 ·
A vial holds its volume in mL times its concentration in mg/mL: a 2 mL vial at 5 mg/mL holds 10 mg. Doses = total mg ÷ the dose on your label. Time counts too: the FDA (page current as of October 1, 2026) says to discard a multiple-dose vial 28 days after first use.
How much medicine is in a vial?
Quick answer: Multiply the vial’s volume in mL by its concentration in mg/mL. Both numbers are on your vial label.
Use the dose on your label from your REMEVi provider; this page explains the units, it does not set your dose.
A vial label gives two numbers that matter here: how much liquid is in it (mL) and how strong that liquid is (mg/mL). Multiply them and you get the total milligrams of medicine in the vial. The table below does that arithmetic for a few example vial sizes and concentrations. On a U-100 syringe, every mL is also 100 units, so the second column shows the vial’s volume in units.
The FDA notes that compounded semaglutide comes in varying concentrations (FDA alert, July 26, 2024), so two vials of the same size can hold very different amounts of medicine. That is why the only numbers that count are the ones on your own label.
| Vial volume | Units on a U-100 scale | Semaglutide at 2.5 mg/mL | Semaglutide at 5 mg/mL | Tirzepatide at 10 mg/mL | Tirzepatide at 17 mg/mL |
|---|---|---|---|---|---|
| 1 mL | 100 | 2.5 mg | 5 mg | 10 mg | 17 mg |
| 2 mL | 200 | 5 mg | 10 mg | 20 mg | 34 mg |
| 2.5 mL | 250 | 6.25 mg | 12.5 mg | 25 mg | 42.5 mg |
| 4 mL | 400 | 10 mg | 20 mg | 40 mg | 68 mg |
Vial sizes and concentrations here are examples for the arithmetic, not a description of what your pharmacy sends. Read both numbers from your own vial label.
How many doses are in my vial?
Quick answer: Divide the total mg in the vial by the mg per dose on your label. That is the most the liquid allows — not how long you may use the vial.
The formula is: doses = total mg in the vial ÷ mg per dose on your label. If your label gives your dose in units instead, use units on both sides: doses = vial mL × 100 ÷ units per dose. Both give the same answer when the label is right, which also makes them a useful cross-check.
We don’t put a number of doses on this page, because that depends on your dose, and only your REMEVi provider sets it. When your provider changes your dose, the number of doses left in the vial changes too. If the math says you will run out before your next shipment — or that you will have a lot left over — tell your care team instead of adjusting the dose. How to read units and mg on your syringe.
How long can I use a vial after I open it?
Quick answer: No longer than 28 days after the first puncture, or the beyond-use date on the label if that comes sooner — even if medicine is left.
The FDA’s guidance on compounded GLP-1 drugs (current as of October 1, 2026) is direct: “Discard the vial within 28 days after the first use, even if medication remains in the vial. Do not continue using medication from the vial after 28 days, even if instructions from the compounder say the medication can be used for longer than 28 days.” The reason it gives is an increased risk of contamination after 28 days.
The pharmacy standard says the same thing from the other side. USP’s chapter on sterile compounding, quoted in its FAQs updated December 11, 2023, says that after a multiple-dose preparation is first entered or punctured, it “must not be used for longer than the assigned BUD or 28 days, whichever is shorter.”
| Rule | What it says | Source and date |
|---|---|---|
| 28 days after first use | Discard the vial even if medicine remains, even if the compounder says longer. | FDA, October 1, 2026 |
| Beyond-use date (BUD) | The date (or hour and date) after which the compounded preparation must not be used. | USP <797> FAQs, December 11, 2023 |
| After first puncture | Use no longer than the BUD or 28 days, whichever is shorter. | USP <797> FAQs, December 11, 2023 |
| USP’s own example | A vial with a 60-day BUD must still be discarded no later than 28 days after first puncture. | USP <797> FAQs, December 11, 2023 |
What is a beyond-use date (BUD)?
Quick answer: USP defines it as “the date, or the hour and date, after which” a compounded sterile preparation “must not be used.” Your pharmacy prints it on the label.
A beyond-use date is set by the pharmacy that prepared the vial. USP is clear that the BUD and the “in-use time” — how long you can use a vial once it is open — are two different limits. A vial can have a BUD weeks away and still reach its 28-day limit first, because the 28 days start at the first puncture.
USP also notes that longer BUDs are generally allowed for preparations stored colder, because cold slows the growth of most microorganisms. That is one reason to follow the storage line on your label exactly. Writing the date of your first puncture on a calendar or on the carton makes the 28-day count easy to track.
What do the brand-name vial labels say?
Quick answer: Lilly’s labels say to throw away an opened Zepbound® or Mounjaro® multi-dose vial after 30 days or 4 weekly doses. Those are brand facts, not compounded rules.
For its own multi-dose vial, Lilly’s Zepbound® label (revised 08/2026) says to throw away an opened vial “after a total of 30 days at room temperature, 30 days after first use, or after taking 4 weekly doses, even if there is medicine left in it.” The Mounjaro® label (revised 08/2026) says the same for that product. Lilly’s single-dose vial instructions (revised April 2026) say to throw away all opened vials after use.
Wegovy®, Ozempic®, Zepbound® and Mounjaro® are FDA-approved brand-name products that REMEVi does not sell. Facts quoted from their labels describe those products only. We name them to orient you, not to suggest a compounded medication is equivalent to them.
For a compounded vial, follow your pharmacy label, its beyond-use date and the FDA’s 28-day limit — whichever ends first.
What if my vial runs out early or has medicine left?
Quick answer: Call your REMEVi care team. Don’t use leftover medicine past 28 days, and don’t change your dose to make a vial last.
Leftover medicine at day 28 is expected sometimes, and the FDA is clear that it still goes in the trash. Running out early is a different signal: it can mean the dose is being measured differently from your label. Either way, the fix is a call, not a change in how much you draw.
Use a new, sterile needle and syringe for every dose — the FDA says reusing them can contaminate the medicine in the vial (October 1, 2026). Which needle and syringe are used.
Questions about your vial, syringe or label? Message your REMEVi care team or call (702) 352-4746 before you inject.
Compounded semaglutide and tirzepatide are prepared by licensed pharmacies for an individual prescription. They are not FDA-approved, and the FDA has not reviewed them for safety, effectiveness or quality.
Frequently asked questions
Can I keep using a vial after 28 days if there is medicine left?
No. The FDA says to discard a multiple-dose vial within 28 days after first use, even if medication remains and even if the compounder’s instructions say longer.
Does the 28 days start when the vial arrives?
No — they start at the first use (first puncture). But the beyond-use date on the label still applies, and it can come sooner.
Why does the FDA say 28 days?
Because there is an increased risk of contamination after 28 days, according to the FDA.
Does a bigger vial last longer?
It can hold more doses, but the time limit does not grow with it: the 28-day and beyond-use limits still apply.
How do I know how many units are in my vial?
On a U-100 scale, multiply the vial’s mL by 100. A 2 mL vial is 200 units of liquid.
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