Semaglutide injections are prescription GLP-1 medications given under the skin, usually once a week. The active drug remains the same, but the device may be a prefilled pen, a prefilled syringe or a pharmacy-dispensed vial used with a separate syringe. That difference changes preparation, storage and disposal—not semaglutide's basic pharmacology. The prescriber sets the dose and schedule. Product-specific instructions matter most on a missed week or when medication has been left out of the refrigerator.
What semaglutide injections actually are
A semaglutide injection delivers medication into the fatty tissue beneath the skin rather than into a muscle or vein. From there, the drug is absorbed gradually. Its long stay in the body is what makes a weekly schedule possible: a randomized pharmacokinetic study found a half-life of about one week (Ikushima et al., Advances in Therapy, 2018). A half-life is the time required for the amount circulating in the body to fall by roughly half; it is not the point when the medication suddenly stops working.
The injection schedule is separate from the titration schedule. A weekly interval can remain steady while the prescribed amount changes over time. The reviewing provider determines that amount. How long semaglutide stays in the system explains the longer washout in more detail.
Because semaglutide remains in circulation between injections, injection day is only one point in a continuous treatment cycle. A late dose is not equivalent to starting from zero, and an extra dose can overlap with medication already present. That helps explain why missed-dose labels use timing windows rather than a simple make-up rule. The weekly rhythm is a pharmacologic feature, not simply a convenience of the device.
Pen, syringe and vial formats are not interchangeable
The device tells you how the dose is prepared. It does not make two differently labeled products equivalent. As of August 2026, the current Ozempic label lists single-patient pens containing multiple weekly doses, as well as single-dose prefilled syringes. The current Wegovy label lists the familiar disposable single-dose pens, single-dose prefilled syringes and a four-dose FlexTouch presentation.
A compounded prescription may instead arrive in a vial with separate syringes. The concentration, beyond-use date and directions come from the dispensing pharmacy and the prescription, so brand instructions cannot be transferred automatically to a compounded vial. Promise's semaglutide is dispensed as a compounded medication, which is different from an FDA-approved product: the formulation offered here is not FDA-approved. Regulatory status does not decide treatment by itself: a licensed provider may still prescribe a compounded formulation when clinically appropriate, and that choice belongs to the patient and prescriber.
| Format | What is prepared for one injection | What happens afterward |
|---|---|---|
| Multi-dose pen | The prescribed dose is selected from a pen holding several doses | The pen is stored for later weekly use |
| Single-dose pen or syringe | One premeasured dose | The whole device goes into sharps disposal |
| Compounded vial | A separate syringe is filled according to the prescription | The syringe is discarded; the vial is stored as labeled |
What injection day is usually like
The practical routine is short: the correct product and prescribed amount are confirmed, the injection is given under the skin, and the used sharp is contained immediately. Meals do not determine the timing of injectable semaglutide under the Ozempic and Wegovy labels. Detailed technique and site selection belong in the semaglutide injection guide, including why rotating sites matters.
The larger consideration is often how the following day or two feels. In STEP 1, a 68-week trial of once-weekly subcutaneous semaglutide, nausea and diarrhea were the most common adverse events; they were usually temporary and mild to moderate (Wilding et al., New England Journal of Medicine, 2021). A mild pinch at the moment of injection and gastrointestinal effects from the medication are different experiences. Persistent vomiting, severe abdominal pain, signs of dehydration or an allergic reaction warrant prompt medical advice.
Tirzepatide is another weekly injectable that people often compare with semaglutide, but it is a different molecule with its own prescription and label. The tirzepatide versus semaglutide comparison covers that decision rather than treating the devices as substitutes.
A missed dose depends on the label
There is no single missed-dose rule for every semaglutide injection. The May 2026 Ozempic label says a missed dose may be administered within five days; after more than five days, it is skipped and the regular weekly schedule resumes. The June 2026 Wegovy injection label uses the next scheduled dose as the reference: a missed dose may be given when that next dose is more than 48 hours away, but is skipped when it is less than 48 hours away. After two or more consecutive missed Wegovy injection doses, the label calls for restarting at a lower step to reduce gastrointestinal effects.
Those are brand-label rules, not universal instructions for a compounded vial. The prescription label and reviewing provider control when directions differ. Doubling a dose to make up for a missed week is not part of either brand rule.
Storage follows the product, not the molecule
Unopened Ozempic and Wegovy injections are generally refrigerated at 36°F to 46°F (2°C to 8°C) and should not be frozen. Their room-temperature windows differ. The current Ozempic label allows a multi-dose pen to remain refrigerated or at 59°F to 86°F for 56 days after first use. The current Wegovy label allows a capped single-dose pen or syringe to stay at 46°F to 86°F in its carton for up to 28 days; its FlexTouch format has a different after-first-use window.
Compounded preparations have pharmacy-specific beyond-use dates and storage directions. The vial label takes priority over a brand website or another person's carton. Semaglutide expiration and refrigeration covers temperature excursions, freezing and beyond-use dates without guessing from appearance alone.
Disposal and clinical follow-up complete the routine
Pens, prefilled syringes and detachable needles all count as sharps. The FDA recommends placing them in an FDA-cleared sharps container immediately after use and following local rules once the container is about three-quarters full (FDA sharps guidance). Loose sharps do not belong in household trash, recycling or a toilet. A heavy-duty, leak-resistant plastic household container with a tight puncture-resistant lid may be an alternative when local guidance permits and a cleared container is unavailable.
At Promise, a licensed provider reviews every request, and not everyone qualifies for a prescription. That relationship matters after the first shipment too: device uncertainty, repeated missed doses, storage mistakes and symptoms that are difficult to manage are reasons to contact the care team rather than improvise from another product's instructions.