How to store Zepbound and Mounjaro
Fridge, travel, freezing, and what to do when things go wrong
Quick read · 4 min
Keep tirzepatide pens in the fridge between 36–46°F (2–8°C) until you first use them. Once opened, you can keep them at room temperature (below 86°F / 30°C) for up to 21 days. Never let the pen freeze — if it freezes, even once, throw it away.
- •Fridge: 36–46°F (2–8°C) until the expiry date on the box
- •Room temperature once opened: up to 21 days (not 28 — different from Wegovy)
- •Never freeze — damaged even if it thaws and looks normal
- •Middle shelf of the fridge, not the door or the back
- •Travel with an insulated cool bag — never put ice directly on the pen
- •Dispose in a sharps container — never household bin
Based on clinical trials · No rankings · Every claim linked to source
Two places you can keep it
The fridge is the long-term home. Once you take a pen out, the room-temperature clock starts.
- •Store in the original carton to protect from light
- •Middle shelf is best — most stable temperature
- •Do not store in the fridge door (temperature swings)
- •Avoid the back wall (may freeze when the compressor cycles)
- •Do not use the crisper drawer (too humid)
Important: After 21 days at room temperature, the pen must be discarded — even if there is still medicine in it. This is shorter than the Wegovy/Ozempic window (28 days), so the two drugs are not interchangeable on this. Write the date you first took it out of the fridge on the box.
Where in the fridge
Not all fridge shelves are equal. The door swings in temperature and the back wall can briefly freeze.
- ✓Middle shelf is best — most stable temperature
- ✗Not the door — temperature swings every time it opens
- ✗Not the back wall — may freeze when the fridge cycles
- ✗Not the crisper drawer — too humid, can damage the pen
Safe vs damaging conditions
Getting this wrong means the drug silently stops working — the pen looks identical either way.
- •Between 36°F and 46°F in the fridge (2–8°C)
- •Up to 21 days at room temperature (below 86°F / 30°C)
- •Travelling in an insulated cool bag with a cold pack (not touching the pen)
- •Keeping the pen in the original carton to shield it from light
- •Carrying the pen through airport security in hand luggage
- •Freezing — even once, even briefly, even if it thaws
- •Temperatures above 86°F (30°C) — a hot car, direct sunlight
- •Keeping it out of the fridge for more than 21 days
- •Putting a pen fresh from the fridge into a checked suitcase (cargo hold can be very cold)
- •Ice packs touching the pen directly — localised freezing
- •Shaking the pen vigorously
Travelling with your pen
The 28-day room-temperature window makes travel simpler than it sounds, but there are rules.
Never put the pen in checked baggage. Airplane cargo holds can drop well below freezing, which permanently damages the drug.
For flights over a few hours, use a dedicated insulin travel case with a cold pack. Wrap the cold pack so it does not touch the pen directly — direct contact can freeze it.
TSA and most international airports allow injectable medication through security. Bring the original box with the prescription label. You do not need a doctor's letter, but it can help at some borders.
A car in summer can exceed 140°F in minutes. Any temperature above 86°F shortens the life of the pen. If you are worried, take it with you into air-conditioned spaces.
How to spot a damaged pen
The big trap: a frozen-then-thawed pen looks completely normal. Check these signs before every injection.
- •The liquid looks cloudy, milky, or coloured (should be clear and colourless)
- •You can see particles, flakes, or floating debris
- •The pen has been frozen at any point (even if it now looks normal)
- •The pen has been above 86°F for extended time (e.g. left in a hot car)
- •The expiry date on the box has passed
- •The pen has been at room temperature for more than 21 days
- •The pen is cracked, leaking, or the needle is damaged
If in doubt, call your pharmacy — most will replace a damaged pen if you bring it in.
Disposing of used pens
Never the regular bin. Needles need a sharps container.
- 1Use a proper sharps container from your pharmacy (often free) — never a regular bin
- 2Do not recap the needle before disposing — recapping is when needle-stick injuries happen
- 3When the sharps container is full, take it back to your pharmacy or a needle disposal site
- 4Never flush pens or needles down the toilet
- 5If you do not have a sharps container, a thick plastic detergent bottle with the cap taped shut is a stopgap, but get a proper one as soon as you can
Based on clinical trials · No rankings · Every claim linked to source
Last reviewed: March 2026