How Long Can Mounjaro Be Out of the Fridge? Every Pen and Vial

An opened UK Mounjaro (tirzepatide) KwikPen can be kept out of the fridge at room temperature, no more than 30°C, for up to 30 days, and is then thrown away (Mounjaro SmPC, section 6.4). Until its first injection, the pen belongs in the fridge at 2°C to 8°C. In the US, single-dose Mounjaro pens and vials allow a total of 21 days up to 30°C (86°F), and no label lets you use a pen that has frozen (Mounjaro label, section 16.2).

Key facts

• A UK Mounjaro KwikPen holds 4 doses, so taken weekly its 4th dose falls 21 days after the first, leaving 9 of its 30 days spare (Mounjaro SmPC).
• US Mounjaro and Zepbound single-dose pens allow a total of 21 days up to 30°C (86°F), and Eli Lilly and Company says a Zepbound pen left out should not go back in the fridge (Mounjaro label, section 16.2; Lilly’s Zepbound how-to page).
• A US Mounjaro or Zepbound KwikPen or multi-dose vial is thrown away 30 days after first use or after 4 weekly doses, whichever comes first (Mounjaro label, section 16.2; Zepbound label, section 16.2).
• A Mounjaro pen that has frozen is never used, even inside its 30 days (Mounjaro patient leaflet, section 5).
• No Mounjaro, Zepbound, Ozempic or Wegovy pen or vial may be stored above 30°C (86°F), and the US Wegovy label says to throw a pen away if it got hotter (Wegovy label, section 17).

How long can Mounjaro be out of the fridge, opened or unopened?

Once opened, meaning after its first injection, a UK Mounjaro KwikPen can spend up to 30 days out of the fridge at no more than 30°C (Mounjaro SmPC, section 6.4). Unopened, it stays in the fridge at 2°C to 8°C, with no room-temperature allowance at all (Mounjaro SmPC, sections 6.3 and 6.4).

Each UK KwikPen holds 4 doses of 0.6 ml (Mounjaro SmPC); check how KwikPen doses and priming work before your first injection from a new pen. Taken weekly, the 4th dose falls 21 days after the first, which leaves 9 of the 30 days in hand if a dose runs late.

In the US, an unopened Mounjaro KwikPen may spend 30 days at room temperature up to 30°C (86°F) (Mounjaro label, section 16.2).

How long can Zepbound, Ozempic and Wegovy be out of the fridge?

A US Zepbound single-dose pen or vial can be out of the fridge for a total of 21 days up to 30°C (86°F), and an unopened Zepbound KwikPen or multi-dose vial for 30 days (Zepbound label, section 16.2). An in-use Ozempic pen keeps for 56 days in the US but 6 weeks in the UK (Ozempic label, section 16; Ozempic SmPC, section 6.3).

Ozempic and Wegovy multi-dose pens get no room-temperature days before first use. Only the single-dose Wegovy pens and the US Ozempic syringe may sit out unused, for up to 28 days, not above 30°C (86°F) (Wegovy label, section 16; Ozempic label).

The table compares every pen and vial, using the current US labels for Mounjaro, Zepbound, Ozempic and Wegovy and the UK SmPCs for Mounjaro, Ozempic, Wegovy FlexTouch and Wegovy 7.2 mg.

"Fridge only" means the label allows an unused pen no room-temperature days.

The US Wegovy FlexTouch Instructions for Use set a tighter in-use range, 20°C to 25°C (68°F to 77°F), so keep the pen within it or in the fridge (Wegovy FlexTouch Instructions for Use). Ozempic’s US pen instructions say to bin the pen after 56 days even with medicine left, and to write that date on your calendar (Ozempic pen Instructions for Use).

If you use a vial, check how much is in each Zepbound vial before you draw your first dose. If you are taking the Wegovy pill, it needs no fridge; the US label keeps the tablets in their original bottle at 20°C to 25°C (68°F to 77°F) (Wegovy label, section 16).

Can Mounjaro go back in the fridge after being left out?

An opened US Mounjaro or Zepbound KwikPen or multi-dose vial can go back in the fridge, because the label lets you keep it in the fridge or at room temperature up to 30°C (86°F) (Mounjaro label, section 16.2). It is still thrown away at the first of 30 days after first use, 4 weekly doses or a total of 30 days at room temperature.

The US Mounjaro and Zepbound labels allow single-dose pens "a total of 21 days" out of the fridge, wording that lets separate spells add up (Zepbound label, section 16.2). Lilly’s how-to page for the Zepbound single-dose pen is stricter: "If Zepbound is stored at room temperature, it should not be returned to the refrigerator" (Lilly’s Zepbound how-to page). It also says to discard the pen if it is not used within 21 days of leaving the fridge. The US Mounjaro single-dose pen carries the same "total of 21 days" label wording (Mounjaro label, section 16.2), so give either pen one trip out of the fridge and use it within 21 days.

The UK SmPC sets no rule against putting an in-use Mounjaro KwikPen back in the fridge. It says to store the pen at 2°C to 8°C and allows up to 30 days unrefrigerated, not above 30°C, after first use (Mounjaro SmPC, section 6.4). Either way, the pen is thrown away 30 days after its first use (Mounjaro patient leaflet, section 5).

For a KwikPen, the date to keep is the day of its first injection, and Pensday keeps it next to the dose it belongs to. Every injection you log is dated in your shot history, and you can add a note such as "new KwikPen" to that dose. Dose logging and shot-day reminders are free; Pensday does not count storage days for you.

What if Mounjaro was left out of the fridge overnight or for a few days?

An opened UK Mounjaro KwikPen left out overnight, for 24 hours or for 2 or 3 days is still within its allowance if it stayed at no more than 30°C (Mounjaro SmPC, section 6.4). It must also be inside 30 days from its first use.

An unopened UK KwikPen is different, because the SmPC gives it no room-temperature allowance at all (Mounjaro SmPC, sections 6.3 and 6.4). Before you use a pen that sat out unopened, ask the pharmacist who supplied it.

In the US, an unopened Mounjaro KwikPen or multi-dose vial has 30 days at room temperature up to 30°C (86°F), and those days still count once you start it (Mounjaro label, section 16.2). A US Mounjaro or Zepbound single-dose pen or vial left out for 3 days, with no earlier time out, has used 3 of its 21 days and has 18 left; a Zepbound pen then stays out of the fridge, as Lilly’s page says (Lilly’s Zepbound how-to page).

What if Mounjaro froze in the fridge?

Throw it away (Mounjaro label, section 16.2). The UK leaflet says, "If the pen has been frozen, DO NOT USE," and a pen that has since thawed has still been frozen (Mounjaro patient leaflet, section 5). The US instructions agree: "If the Pen has been frozen, throw the Pen away and use a new Pen" (Mounjaro single-dose pen Instructions for Use).

Novo Nordisk’s labels also say to keep Ozempic and Wegovy pens away from the fridge’s cooling element (Ozempic SmPC, section 6.4; Wegovy FlexTouch SmPC, section 6.4). For syringes, the US Ozempic and Wegovy instructions rule out any that has been "frozen or thawed" (Ozempic label; Wegovy syringe Instructions for Use).

If a frozen pen means you have missed a Mounjaro dose, take it as soon as possible within 4 days (96 hours) of when it was due (Mounjaro SmPC, section 4.2; Mounjaro label, section 2.1). After that, skip it and inject on your usual day. The missed dose guide works out that deadline to the hour.

What if Mounjaro was left in a hot car, in the sun or in hot weather?

A Mounjaro pen that sat above 30°C (86°F) in a hot car or in the sun is outside its label, since no Mounjaro or Zepbound label allows storage above 30°C (Mounjaro label, section 16.2). The US label says, "Protect MOUNJARO from heat and light," and, unlike the Wegovy documents, gives no rule for using a pen that got hotter. Ask the pharmacist who supplied it before you inject it.

In hot weather, keep the pen in the fridge whenever the room is warmer than 30°C (86°F), in its original carton to protect it from light (Mounjaro SmPC, section 6.4; Mounjaro label, section 16.2).

Wegovy’s US label goes further and says to throw away a single-dose pen, syringe or FlexTouch pen exposed to light or to temperatures above 30°C (86°F) (Wegovy label, section 17). The UK leaflet for the Wegovy 7.2 mg pen says the same (Wegovy 7.2 mg patient leaflet, section 5).

The UK Ozempic and Wegovy FlexTouch leaflets say not to inject medicine that has been in direct sunlight (Ozempic patient leaflet; Wegovy FlexTouch patient leaflet). Keeping the pen cap on protects an Ozempic pen from light (Ozempic SmPC, section 6.4).