How to store Zepbound and Mounjaro

The rules at a glance

All formats start in the fridge. From Lilly's Instructions for Use for each Zepbound device and the Mounjaro prescribing information.^{[1, 3, 2, 5]} Your leaflet is the final word for the device in your hand.

In the fridge

Every Zepbound and Mounjaro format should be stored in the refrigerator at 36°F to 46°F (2°C to 8°C) until you need it.^{[1, 3, 2, 4]} Keep pens and vials in their original carton to protect them from light.^{[3, 4, 5]}

• Keep them away from the freezer compartment and the cold plate at the back of the fridge, where items can freeze.
• A fridge thermometer is an inexpensive way to check your fridge actually sits in the 36°F to 46°F range.

You do not need to let a single-dose pen warm up before injecting. Both the Zepbound and Mounjaro pen instructions say it is not necessary to warm the pen to room temperature.^{[1, 4]}

Out of the fridge: the 21-day rule

Single-dose pens and single-dose vials can be kept at room temperature up to 86°F (30°C) for up to a total of 21 days. After a total of 21 days at room temperature, throw them away.^{[1, 3, 4, 5]}

Two words in that rule matter. "Total" means the days add up: three days out on one trip and five on another count as eight. "86°F" is a ceiling: room temperature here does not mean a hot car, a sunny windowsill or a summer beach bag. The Mounjaro prescribing information says to protect the medicine from heat and light.^[5]

KwikPens and multi-dose vials: the 30-day rule

KwikPens hold four weekly doses, so their rules are built around first use rather than a running total.

Zepbound KwikPen

• Store unused pens in the fridge.^[2]
• After your first injection, you may keep the pen at room temperature up to 86°F (30°C), away from heat and light.^[2]
• Throw the pen away 30 days after first use, even if medicine is left in it.^[2]
• Take the needle off after every injection and store the pen with its cap on. Leaving a needle attached can cause leaking, a blocked needle and air in the pen.^[2]

Mounjaro KwikPen and multi-dose vial

The Mounjaro prescribing information lists a single-patient-use KwikPen and a multi-dose vial, each holding four doses. Unopened, they go in the fridge. If kept at room temperature (up to 86°F), throw an unopened one away after 30 days. Once opened, throw it away after a total of 30 days at room temperature, 30 days after first use, or after 4 weekly doses, whichever comes first, even if medicine is left.^[5]

Frozen, hot, dropped or cloudy

• Frozen: do not use it, even after it thaws. Throw it away.^{[1, 2, 3, 4]}
• Dropped single-dose pen: if it falls on a hard surface, do not use it. Use a new pen.^{[1, 4]}
• Looks wrong: the liquid should be colorless to slightly yellow. Do not use it if it is cloudy, discolored or has particles.^{[1, 3]}
• Got too hot or you lost count of the days: the instructions do not give an exception for this. Ask your pharmacist, or call Lilly on 1-800-545-5979, before you use it.^[1]

Keeping track of the days

The 21 and 30-day rules are easy to lose track of, especially with a spare pen in a bag or a trip away. A few habits help:

• Write the date on the carton when a single-dose pen or vial first leaves the fridge, and again each time it does.
• Write the date of your first injection on a KwikPen carton.
• Use the note field in the injection logbook to record when a pen came out of the fridge. It stays on your device only.

Traveling soon? The rules above still apply on the road. Keep the medicine in its carton and away from heat, and carry it with you rather than in checked luggage where temperatures are out of your control.

Common questions