Key takeaways
- Wegovy and Ozempic contain semaglutide and work as GLP-1 receptor agonists.
- Mounjaro contains tirzepatide, a dual incretin therapy studied in SURMOUNT-1 with large average weight reductions over 72 weeks.
- Before use, these pens should generally be stored refrigerated, protected from heat and light, and never frozen.
- Out-of-fridge limits differ: Wegovy 28 days , Mounjaro 21 days , Ozempic 56 days after first use (within allowed temperatures).
- Correct storage supports safety and effectiveness, but long-term results still come from a holistic plan: nutrition, movement, sleep, and consistency.
If you’re starting your journey to lose weight and improve long-term health, you may be considering medically supported options like Wegovy, Mounjaro, or Ozempic. These prescription injections can be powerful tools when they’re used safely and alongside sustainable lifestyle changes.
One often-missed step is practical: how to store your medication correctly —at home, day-to-day, and while travelling. Storage affects medication stability, and the goal is simple: keep your pen safe, effective, and ready to use when you need it.
This blog compiles the key dos and don’ts for storing GLP-1-based weight-management injections, so you can feel confident about protecting your medication while you focus on your progress.
How are Wegovy, Mounjaro and Ozempic different from each other?
Even though these medicines are often spoken about together, they are not all the same.
Who are they prescribed to?
- Ozempic is a GLP-1 receptor agonist indicated for adults with type 2 diabetes (and for certain cardio-renal risk-reduction indications in specific groups).
- Wegovy is a GLP-1 receptor agonist used for chronic weight management in eligible patients (and also has a cardiovascular risk-reduction indication in certain adults).
- Mounjaro (tirzepatide) is widely used for metabolic health and weight goals in clinical practice, and evidence from major trials shows substantial weight reduction in adults with obesity or overweight.
What do they contain?
- Wegovy and Ozempic contain semaglutide .
- Mounjaro contains tirzepatide .
What is their dosage frequency?
- Ozempic and Wegovy are taken once weekly .
- Mounjaro is also dosed once weekly in clinical trials and standard use.
Side effects (what patients commonly feel)
Like all prescription medications, these can cause side effects, and everyone’s experience can be different.
- For Ozempic , common side effects reported in clinical trials include nausea, vomiting, diarrhoea, abdominal pain, and constipation.
- For Wegovy , common side effects include nausea, diarrhoea, vomiting, constipation, abdominal pain, headache, and fatigue (among others).
How do Wegovy, Ozempic and Mounjaro function?
How Wegovy and Ozempic work (semaglutide)
Wegovy and Ozempic work by mimicking GLP-1 (glucagon-like peptide-1), a natural hormone involved in appetite regulation and blood sugar control.
Semaglutide helps manage blood sugar through several actions described in prescribing information, including:
- Increasing insulin release when blood sugar is high.
- Reducing glucagon (which lowers the liver’s glucose output).
- Slowing stomach emptying (which can help reduce post-meal blood sugar spikes and support fullness).
This is also why many patients notice reduced appetite and fewer cravings over time, especially when medication is paired with nutrition and activity changes.
Important safety note: semaglutide medicines have a boxed warning/contraindication related to medullary thyroid carcinoma (MTC) and MEN2 risk history.
How Mounjaro works (tirzepatide)
Tirzepatide is described as a dual-acting incretin therapy (GIP/GLP-1 receptor agonist) and has shown strong weight-loss results in large clinical trials.
Weight loss medications compared: Wegovy vs Mounjaro (evidence snapshot)
Both semaglutide and tirzepatide have shown clinically meaningful weight reduction in major trials.
- In the STEP 1 trial (68 weeks), adults taking semaglutide had a mean weight change of −14.9% vs −2.4% with placebo, and an average loss of 15.3 kg vs 2.6 kg with placebo.
- In SURMOUNT-1 (72 weeks), the mean percentage change in body weight was −15% , −19.5% , and −20.9% for tirzepatide 5 mg, 10 mg, and 15 mg, versus −3.1% for placebo.
- In the same SURMOUNT-1 report, 90.9% of participants in the 15 mg group lost at least 5% of starting weight (vs 34.5% with placebo).
These medicines work best as part of a broader plan—adequate protein, fibre, hydration, sleep, movement, and a realistic calorie deficit—so results are easier to maintain long term.
Best way to store Ozempic
Correct storage helps keep your medication effective and safe.
Ozempic storage dos
- Store unopened Ozempic pens in the refrigerator (commonly 2°C to 8°C).
- After first use, you can store an opened pen in the refrigerator or at room temperature 15°C to 30°C .
- An opened Ozempic pen can be used for up to 56 days , and should be discarded after that even if medication remains.
Ozempic storage don’ts
- Do not freeze Ozempic; do not use a pen that has been frozen.
- Avoid placing it right next to the fridge cooling element (where it may accidentally freeze).
- Keep it away from direct sunlight and heat (for example, don’t leave it in a car).
If you’re ever unsure whether your pen is still okay after accidental heat exposure or a fridge power cut, speak to your pharmacist/clinician before injecting.
Does Wegovy require refrigeration?
Yes-Wegovy should generally be stored in the fridge, but it has a defined room-temperature allowance.
Wegovy storage best practices
- Store Wegovy pens in the refrigerator.
- If needed, Wegovy can be kept out of the fridge for up to 28 days as long as it is kept at 30°C or less and protected from light.
- Keep Wegovy in the original carton until use to help protect it from light exposure.
- Do not freeze Wegovy, and do not use it if it has been frozen.
If you still have questions about storage (especially in hot climates or during travel), it’s always best to confirm with your healthcare provider.
Does storing Mounjaro need refrigeration?
Yes—Mounjaro should be refrigerated for routine storage, with a limited room-temperature window.
Mounjaro storage best practices
- Store Mounjaro in the refrigerator (commonly 2°C to 8°C).
- If needed, Mounjaro remains effective for up to 21 days at room temperature as long as it does not go above 30°C .
- Keep it protected from light (ideally in its original packaging).
- Do not freeze Mounjaro.
How long can weight-loss injections be kept out of the fridge?
Here are the corrected “out of fridge” timelines people commonly need for travel or temporary refrigeration issues:
- Wegovy: up to 28 days (≤30°C, protect from light).
- Mounjaro: up to 21 days (≤30°C).
- Ozempic: up to 56 days after first use at room temperature 15°C to 30°C (or refrigerated), then discard.
If a pen goes above the recommended temperature limit, is frozen, or is left out longer than allowed, it may not be reliable—so check with a pharmacist/clinician before use.
References
- Ozempic® official U.S. prescribing information (FDA PDF): https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/209637s025lbl.pdf
- Wegovy® prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid='f5e548d0-cc79-4c34-a3f5-e20a5b8b6564
- STEP 1 trial (PubMed – once-weekly semaglutide in adults with overweight or obesity): https://pubmed.ncbi.nlm.nih.gov/33567185/
- SURMOUNT-1 trial summary (American College of Cardiology): https://www.acc.org/Latest-in-Cardiology/Clinical-Trials/2022/08/04/15/32/SURMOUNT-1
- Mounjaro travel/storage guidance (MedicalNewsToday): https://www.medicalnewstoday.com/articles/drugs-mounjaro-travel
- Wegovy refrigeration/storage overview (Healthline): https://www.healthline.com/health/drugs/wegvoy-and-refrigeration
- Ozempic storage & travel overview (MedicalNewsToday): https://www.medicalnewstoday.com/articles/drugs-does-ozempic-need-to-be-refrigerated
