How should I store a Wegovy pen?

The Wegovy Medication Guide says to store the pen in the refrigerator between 36°F and 46°F (2°C to 8°C), in the original carton to protect it from light, and not to freeze it. If needed, before the pen cap is removed, it can be stored between 46°F and 86°F (8°C to 30°C) in the original carton for up to 28 days.

How long can Zepbound stay out of the refrigerator?

Section 16.2 of the Zepbound label says a single-dose pen or single-dose vial can be stored unrefrigerated at up to 86°F (30°C) for a total of 21 days, then must be discarded. The multi-dose vial and single-patient-use KwikPen follow a 30-day rule: throw them away after a total of 30 days at room temperature, 30 days after first use, or after 4 weekly doses, even if medicine is left.

Do I need to warm the pen before injecting?

The Zepbound pen instructions say it is not necessary to warm the pen to room temperature. We did not find an equivalent warming instruction in the Wegovy sections we read.

Where can I inject, and do I rotate the site?

Wegovy is injected under the skin of the abdomen, thigh or upper arm; its Medication Guide says to rotate the injection site with each injection. Zepbound is injected under the skin of the abdomen or thigh, or in the back of the upper arm by another person, and the label says to rotate sites each dose. Neither is injected into a muscle or vein.

How common are injection site reactions?

In the Wegovy label's adult trials, 1.4% of Wegovy patients and 1.0% of placebo patients had injection site reactions, such as itching, redness, inflammation, hardness or irritation. Zepbound lists injection site reactions among its common adverse reactions, and says they were more frequent in patients who developed anti-tirzepatide antibodies (11.3% vs. 1%). Your prescriber decides what to do about a reaction.

Do these rules apply to compounded semaglutide or tirzepatide?

No. These rules come from the labels of FDA-approved brand products. A compounded vial has no FDA label; storage, beyond-use dating and injection instructions come from the prescriber and the pharmacy. Ask for them in writing.

GLP-1 Pen Storage and Injection Sites: What the Wegovy and Zepbound Labels Say

Q: When should I throw a pen away?

For Wegovy, the Medication Guide says to throw the pen away if it has been frozen, exposed to light or to temperatures above 86°F (30°C), or out of the refrigerator for 28 days or longer. Zepbound's label says not to use the product if it has been frozen and to discard it after the room-temperature limit for its presentation.

How long Wegovy and Zepbound can sit out of the fridge (28 and 21 days), what ruins a pen, where the labels say to inject and how to rotate sites, plus why compounded vials follow different rules.

Storage is the least glamorous part of a weekly injection and one of the few where the FDA-approved labels give exact, checkable numbers. The two big brand products do not use the same ones.

Wegovy: 28 days, original carton

The Wegovy Medication Guide says to keep the pen in the refrigerator at 36°F to 46°F, in its original carton to protect it from light, and never to freeze it. If needed, before the cap is removed, the pen can be kept at 46°F to 86°F in the carton for up to 28 days. The guide says to throw the pen away if it has been frozen, exposed to light or to temperatures above 86°F, or out of the refrigerator for 28 days or longer.

Zepbound: 21 days, or 30 for the multi-dose formats

Label section 16.2 says: do not freeze, protect from heat and light, keep in the original carton. A single-dose pen or vial may be kept unrefrigerated up to 86°F for a total of 21 days, then discarded. The multi-dose vial and KwikPen follow a 30-day clock instead, and are also discarded after four weekly doses, even if medicine remains. The Zepbound instructions also say you do not need to warm the pen to room temperature before injecting.

Note the word “total”: the 21 days are cumulative, not reset every time the pen returns to the fridge. That is the point people most often miss, and it matters on a hot Houston day in a parked car, where the 86°F ceiling is easy to pass.

Where to inject and rotating sites

Both labels allow the abdomen and thigh; Wegovy also lists the upper arm, while Zepbound says the back of the upper arm should be injected by another person. Both say to rotate sites. Zepbound’s guide clarifies you may use the same general area as long as the exact spot changes. Neither goes into a muscle or a vein.

Injection site reactions

In Wegovy’s adult trials, 1.4% of patients on the drug and 1.0% on placebo had injection site reactions (itching, redness, inflammation, hardness, irritation). Zepbound lists them as a common reaction and reports they were more frequent in patients who developed anti-tirzepatide antibodies, 11.3% versus 1%. We did not extract a single comparable all-patient rate for Zepbound, so we do not quote one. If a reaction is spreading or severe, that is a question for your prescriber, not a forum.

Compounded products are different

Every number above belongs to an FDA-approved brand product. A compounded vial has no FDA label, so its storage and beyond-use date are set by the pharmacy and prescriber. If you are not sure which you have, start with how to tell brand from compounded and the red-flags guide, then ask your clinic for written storage instructions.

This is general information from FDA-approved labeling, not medical advice. Every clinic in our directory has a named, NPI-verified prescriber you can ask: browse the verified Houston clinics and read our methodology. For other dose-week questions, see the missed dose FAQ and the post-dose week FAQ.

Sources: U.S. National Library of Medicine, DailyMed, “WEGOVY- semaglutide injection, solution” (Medication Guide, Instructions for Use and Section 6), retrieved October 23, 2026. DailyMed, “ZEPBOUND- tirzepatide injection, solution” (Sections 2, 16.2 and Medication Guide; label dated 2026-08-28), retrieved October 23, 2026.

This article is independent editorial content, not medical advice. See our medical disclaimer.