Opening a semaglutide vial is straightforward: you remove only the small plastic flip-off cap on top, exposing a rubber stopper that stays in place permanently. You never remove the rubber stopper or the metal ring (called an aluminum crimp) that holds it down. These are designed to remain intact for the life of the vial, and your needle punctures directly through the rubber each time you draw a dose.
What You Need Before Starting
Before touching the vial, gather everything so you’re not scrambling mid-process: your sealed semaglutide vial, alcohol prep pads, and (if you’re drawing a dose right away) your prescribed insulin syringe with needle. Having it all within reach keeps the process sterile and efficient.
Wash your hands with soap and water for at least 20 seconds, then dry them completely with a clean towel. Damp hands pick up bacteria more easily, so don’t skip the drying step.
Removing the Cap Step by Step
The plastic flip-off cap sits on top of the vial and pops off easily. Pull it straight up with your thumb or fingers. It doesn’t twist or screw off. Once removed, you’ll see a flat rubber stopper held in place by a metal crimp ring around the vial’s neck. That’s it. The vial is now “open.”
Immediately wipe the exposed rubber stopper with a fresh alcohol prep pad. Use a firm circular motion starting from the center and working outward. Then let the alcohol air-dry for at least 10 seconds before inserting a needle. This drying time is what actually kills microbes. Piercing the stopper while it’s still wet reduces the alcohol’s effectiveness.
You’ll repeat this alcohol-wiping step every single time you draw a dose, not just the first time.
Drawing Medication From the Vial
Semaglutide vials are sealed systems, which means removing liquid creates a vacuum inside. To prevent this (and make the medication flow smoothly into your syringe), you inject a small amount of air first.
Start by pulling back the syringe plunger to draw in air equal to the volume of your dose. For example, if your dose is 5 units, pull the plunger back to the 5-unit mark. Insert the needle through the rubber stopper and push the plunger down to inject that air into the vial. This equalizes the pressure inside.
With the needle still in the vial, turn the vial upside down so the stopper faces the floor. Make sure the needle tip stays submerged in the liquid. Slowly release the plunger, and the medication will flow into the syringe. Pull back to your prescribed dose marking. If you see air bubbles, tap the syringe gently with your finger to float them to the top, then push the plunger slightly to expel them back into the vial. Recheck that you have the correct volume.
Understanding Your Dose in Units
Your prescriber will give you a dose in milligrams, but insulin syringes are marked in units. For a standard 5 mg/mL compounded semaglutide vial, the conversion looks like this:
- 0.25 mg = 0.05 mL = 5 units
- 0.5 mg = 0.1 mL = 10 units
- 1.0 mg = 0.2 mL = 20 units
- 1.75 mg = 0.35 mL = 35 units
- 2.5 mg = 0.5 mL = 50 units
These numbers apply only to vials with a 5 mg/mL concentration. If your vial has a different concentration (check the label), the unit conversion will be different. Your pharmacy or prescriber should provide the exact conversion for your specific vial.
Inspecting the Medication
Before every dose, hold the vial up to the light and look at the liquid. Semaglutide solution should be clear and colorless. If you notice cloudiness, floating particles, discoloration, or anything dark or unusual in the vial, do not use it. The FDA has received reports of visible particulate contamination in compounded semaglutide vials, so this visual check is worth the few seconds it takes.
Storage After Opening
Once you’ve punctured the rubber stopper for the first time, the clock starts. Compounded semaglutide vials are generally stable for 28 days after opening when stored in the refrigerator. Keep the vial upright, away from light, and never freeze it. After 28 days, discard any remaining medication even if there’s liquid left. Temperature swings, like leaving the vial on a counter for hours, can degrade the medication faster than that 28-day window suggests.
Between uses, the rubber stopper stays exposed (the flip-off cap doesn’t go back on). This is normal. Just wipe it with alcohol before each needle insertion.
Disposing of Needles Safely
Drop used needles and syringes into a sharps disposal container immediately after each injection. Never recap a used needle, and never toss loose sharps into household trash. If you don’t have a commercial sharps container, a heavy-duty plastic container with a screw-on lid (like a laundry detergent bottle) works as a temporary substitute.
When the container is about three-quarters full, seal it and dispose of it through your local program. Options vary by location but commonly include drop-off boxes at pharmacies, hospitals, or fire stations; household hazardous waste collection sites; and mail-back programs that let you ship sealed containers to a disposal facility. Your local health department or trash removal service can tell you which options are available in your area.