Guides / Storage and travel

Left your pen or peptide out overnight, or it froze?

A night on the counter is often within a GLP-1 pen's label. A frozen pen isn't, on any label. For research peptides, nobody has tested either.

By PeptideTracker editorial team · Updated November 8, 2026 · 12 sources

[00] Short answer

  1. Most GLP-1 pens allow some time out of the fridge, as long as they stay at or below 30 °C (86 °F). One night usually counts toward that allowance1–4,7.
  2. Unused Ozempic, Wegovy FlexTouch, Saxenda and Victoza pens have no allowance before first use. The labels say fridge only1–2,5–6.
  3. Frozen: every GLP-1 label says not to use the medicine if it has been frozen, even once it has thawed1–7.
  4. Over 30 °C: the Wegovy Medication Guide says to throw the pen away if it has been exposed to temperatures above 86 °F (30 °C)2.
  5. Mixed research peptides have no label, so there's no tested answer for a night out or a freeze.

Left a GLP-1 pen out overnight: can you still use it?

Often, yes. A Mounjaro, Zepbound, Wegovy single-dose or Trulicity pen left out overnight at normal room temperature, not above 30 °C (86 °F), is still within its label. The night counts toward the pen's total allowance2–4,7. An unused Ozempic, Wegovy FlexTouch, Saxenda or Victoza pen is the exception.

Out overnight or frozen: what each US label says (section 16 and patient instructions)
Pen or vialOut overnight, at or below 30 °CFrozen, even if thawed
Ozempic or Wegovy FlexTouch pen, already in useWithin the label if it stayed at 15-30 °C: in-use pens can be kept at room temperature for 56 days1–2Don't use it1–2
Ozempic or Wegovy FlexTouch pen, not used yetNot covered. The labels say fridge only before first use1–2Don't use it1–2
Wegovy single-dose pen or syringe, Ozempic syringeWithin the label if it stayed at 8-30 °C. Counts toward 28 days1–2Don't use it. The syringe instructions say "frozen or thawed"1–2
Mounjaro or Zepbound single-dose pen or vialWithin the label if it stayed at or below 30 °C. Counts toward 21 days in total3–4Don't use it3–4
Mounjaro or Zepbound KwikPen or multi-dose vialWithin the label if it stayed at or below 30 °C. Unused: counts toward 30 days. In use: room temperature is allowed3–4Don't use it3–4
Saxenda or Victoza penIn use: within the label at 15-30 °C for 30 days. Not used yet: fridge only5–6Don't use it5–6
Trulicity penWithin the label if it stayed at or below 30 °C. Counts toward 14 days in total7Don't use it7
Research peptide vial, mixedNo label, so no tested answerNo label, so no tested answer

"Not covered" means the label tells you to keep the pen in the fridge before first use and says nothing about time out. That isn't the same as saying the pen is ruined. It means the maker hasn't given a number, so ask your pharmacist or call the maker. The phone numbers in the US labels are 1-888-693-6742 for Ozempic, 1-833-934-6891 for Wegovy and 1-800-545-5979 for Lilly (Mounjaro, Zepbound, Trulicity)1–3.

Full time limits for every pen, including UK differences, are in how long GLP-1 pens can stay out of the fridge.

My GLP-1 pen froze. Can I use it after it thaws?

No. Every GLP-1 label on this page says not to use the medicine if it has been frozen1–7. The Ozempic and Wegovy syringe instructions say "frozen or thawed", so thawing it out doesn't make it usable1–2.

  • How it happens: the Novo Nordisk labels say not to store pens in the freezer or right next to the fridge's cooling element1–2,5–6.
  • Before each dose: the Mounjaro instructions ask you to check the medicine is not frozen, not cloudy, colorless to slightly yellow and without particles3.
  • If you can't tell whether it froze: ask your pharmacist before you use it. They can also tell you how to get a replacement.

What if the pen got hotter than 30 °C (86 °F)?

That's outside every GLP-1 pen label. None allows storage above 30 °C (86 °F)1–7, and the Wegovy Medication Guide says to throw the pen away if it has been exposed to temperatures above 86 °F2. The Ozempic, Wegovy and Saxenda instructions say not to leave the pen in a car or anywhere it can get too hot or too cold1–2,5.

Some labels do describe short temperature excursions, but for other forms. Wegovy tablets are stored at 20-25 °C with excursions allowed to 15-30 °C2. The UK Wegovy pen SmPC says its data support shipping the pen to the patient below 30 °C for up to 48 hours8. That's about controlled delivery, not a pen left in a hot car.

Left a mixed research peptide vial out overnight, or it froze?

Nobody knows, because nobody has tested it. Research peptides like BPC-157 or TB-500 have no prescribing label, so there's no stability data behind any number you see online for a night out or a freeze.

What the general research says, without giving numbers for any one peptide:

  • Most peptide drugs need cold storage and transport, because peptides in solution can be unstable12.
  • Freezing, heating and shaking can make peptides clump together (aggregate)12.
  • Light can trigger oxidation, mostly in peptides that contain the amino acids tryptophan, tyrosine or phenylalanine, or a disulfide bond12.

Approved products mixed with bacteriostatic water show how different the answers can be:

Storage after mixing, from each approved product's US label
Approved productAfter mixing
EGRIFTA WR (tesamorelin), mixed with bacteriostatic waterRoom temperature, 20-25 °C. Throw away 7 days after mixing. Don't freeze9
Omnitrope (somatropin) vial, mixed with its bacteriostatic water diluent (1.5% benzyl alcohol)Fridge, 2-8 °C. Use within 21 days10
Ogivri (trastuzumab-dkst) 420 mg vial, mixed with bacteriostatic waterFridge, 2-8 °C. Throw away after 28 days. Don't freeze11

One must stay out of the fridge and the other two must stay in it. The EGRIFTA WR and Ogivri labels both say not to freeze. There's no home test that tells you how much intact peptide is left in a vial. More on what's known is in how long reconstituted peptides last.

Questions

I left my Mounjaro pen out overnight. Is it ruined?

Not by the label, if it stayed at or below 30 °C (86 °F). A Mounjaro single-dose pen can be unrefrigerated for up to 21 days in total, and the night counts toward that.

My Ozempic pen was out of the fridge all night before I'd used it. Can I use it?

The US label says to keep an unused Ozempic pen in the fridge and doesn't give any time out before first use. It doesn't say what to do if it happens, so ask your pharmacist or call Novo Nordisk on 1-888-693-6742.

Can I use a GLP-1 pen that froze and then thawed?

No. The Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda, Victoza and Trulicity labels all say not to use the medicine if it has been frozen. The Ozempic and Wegovy syringe instructions say frozen or thawed.

Is a reconstituted peptide still good after a night out of the fridge?

There's no tested answer for research peptides. Approved peptides vary a lot: EGRIFTA WR is kept at room temperature for 7 days after mixing, while others must stay in the fridge.

Can I freeze mixed peptides to make them last longer?

There's no published data showing that works for any research peptide. A 2023 review says freezing can make peptides clump together, and the EGRIFTA WR and Ogivri labels say not to freeze them after mixing.

Sources

Checked against US prescribing information for Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda, Victoza and Trulicity (DailyMed, 2025-2026), the EGRIFTA WR, Omnitrope and Ogivri US labels, the UK Wegovy SmPC, and a 2023 review of peptide stability in solution. How we check

  1. 1Ozempic (semaglutide) injection, US prescribing information and Instructions for Use (DailyMed). section 16 and Instructions for Use; version effective June 2026
  2. 2Wegovy (semaglutide) injection and tablets, US prescribing information, Medication Guide and Instructions for Use (DailyMed). section 16 and Medication Guide; version effective June 2026
  3. 3Mounjaro (tirzepatide) injection, US prescribing information and Instructions for Use (DailyMed). section 16.2 and Instructions for Use; version effective August 2026
  4. 4Zepbound (tirzepatide) injection, US prescribing information (DailyMed). section 16.2; version effective August 2026
  5. 5Saxenda (liraglutide) injection, US prescribing information and Instructions for Use (DailyMed). section 16; version effective February 2026
  6. 6Victoza (liraglutide) injection, US prescribing information (DailyMed). section 16; version effective October 2025
  7. 7Trulicity (dulaglutide) injection, US prescribing information (DailyMed). section 16.2; version effective June 2026
  8. 8Wegovy FlexTouch solution for injection in pre-filled pen, UK SmPC. section 6.3; revised 09/2026
  9. 9EGRIFTA WR (tesamorelin for injection), US prescribing information and Instructions for Use (DailyMed). sections 2.2 and 16; version effective July 2026
  10. 10Omnitrope (somatropin), US prescribing information (DailyMed). section 16; version effective July 2025
  11. 11Ogivri (trastuzumab-dkst), US prescribing information (DailyMed). section 2, reconstitution; version effective June 2026
  12. 12Nugrahadi PP et al. Designing formulation strategies for enhanced stability of therapeutic peptides in aqueous solutions: a review. Pharmaceutics 2023;15(3):935. sections on aggregation, light-induced oxidation and cold chain

This guide explains what labels and published studies say. It isn't medical advice and doesn't replace your prescriber or pharmacist.

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