How long does GLP-1 last in the fridge is a common question for patients prescribed glucagon-like peptide-1 receptor agonists for type 2 diabetes or weight management. Proper refrigeration is essential to maintain the stability and efficacy of these biological medications. Unopened GLP-1 pens typically remain stable in the fridge at 2–8°C until their printed expiry date, whilst opened multi-dose pens have specific in-use periods ranging from 30 days to 6 weeks depending on the product. Understanding correct storage requirements helps ensure your medication delivers its intended therapeutic benefit safely and effectively.

What Are GLP-1 Medications and How Should They Be Stored?

Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of injectable medications used primarily for the management of type 2 diabetes mellitus and, in some formulations, for weight management in adults with obesity or overweight with comorbidities. These medications work by mimicking the action of the naturally occurring GLP-1 hormone, which stimulates insulin secretion in a glucose-dependent manner, suppresses glucagon release, slows gastric emptying, and promotes satiety. Common examples available in the UK include semaglutide (Ozempic, Wegovy), dulaglutide (Trulicity), liraglutide (Victoza, Saxenda), and exenatide (Byetta, Bydureon).

GLP-1 medications are biological products—proteins that are sensitive to environmental conditions such as temperature, light, and physical agitation. Proper storage is essential to maintain their structural integrity and therapeutic efficacy. The Medicines and Healthcare products Regulatory Agency (MHRA) and manufacturers provide specific storage instructions to ensure these medications remain safe and effective throughout their shelf life.

Most GLP-1 injections must be stored in a refrigerator at temperatures between 2°C and 8°C before first use. They should be kept in their original packaging to protect them from light and should never be frozen. Freezing can denature the protein structure, rendering the medication ineffective and potentially unsafe. It is also important to keep GLP-1 pens away from the freezer compartment and not to store them in the door of the refrigerator, where temperature fluctuations are more common.

Some GLP-1 products allow limited room-temperature storage before first use. For example, Trulicity (dulaglutide) may be kept at temperatures up to 30°C for up to 14 days, and Bydureon (exenatide prolonged-release) may be kept at up to 30°C for up to 4 weeks before use.

It's important to note that some GLP-1 products are supplied as multi-dose pens (Ozempic, Victoza, Saxenda, Byetta) while others are single-use devices (Wegovy, Trulicity, Bydureon), which affects their storage requirements after opening.

Patients should always check the patient information leaflet supplied with their specific GLP-1 medication, as storage requirements vary between different brands and formulations. If you are unsure about how to store your medication correctly, consult your GP, practice nurse, or community pharmacist for guidance.

How Long Do GLP-1 Injections Last in the Fridge?

The duration that GLP-1 medications remain stable in the fridge depends on whether the pen is unopened or in use, and varies by specific product. Understanding these timelines is crucial for ensuring medication efficacy and patient safety.

Unopened GLP-1 pens can typically be stored in the refrigerator (2°C to 8°C) until the expiry date printed on the packaging. This expiry date is determined by the manufacturer based on stability studies and represents the period during which the medication maintains its full potency when stored correctly.

Storage guidelines for specific GLP-1 products:

• Semaglutide (Ozempic) - multi-dose pen: Before first use, store at 2-8°C. After first use, can be stored at temperatures up to 30°C or in a refrigerator for up to 6 weeks.

• Semaglutide (Wegovy) - single-use pen: Store at 2-8°C. Each unused pen may be kept at temperatures up to 30°C for up to 6 weeks before use. Discard after single injection.

• Dulaglutide (Trulicity) - single-use pen: Store at 2-8°C. May be kept at temperatures up to 30°C for up to 14 days before use. Discard after single injection.

• Liraglutide (Victoza, Saxenda) - multi-dose pen: Before first use, store at 2-8°C. After first use, can be stored at temperatures up to 30°C or in a refrigerator; use within 1 month.

• Exenatide (Byetta) - multi-dose pen: Before first use, store at 2-8°C. After first use, store at or below 25°C and discard after 30 days.

• Exenatide prolonged-release (Bydureon) - single-use: Store at 2-8°C. May be kept at temperatures up to 30°C for up to 4 weeks before use. After reconstitution, use immediately.

For multi-dose pens (Ozempic, Victoza, Saxenda, Byetta), it is important to write the date of first use on the pen label to track how long it has been in use. After the specified in-use period, the medication should be disposed of safely, even if there is solution remaining in the pen. Using medication beyond its recommended in-use period may result in reduced efficacy or increased risk of contamination.

What Happens If GLP-1 Medication Is Not Refrigerated Properly?

Improper storage of GLP-1 medications can compromise their therapeutic effectiveness and safety. Because these are biological products containing protein molecules, they are particularly vulnerable to degradation when exposed to temperatures outside the recommended range.

Exposure to high temperatures (above the recommended limits) can cause the protein structure to denature or break down, reducing the medication's potency. This means that even if the solution appears normal, it may not deliver the intended glucose-lowering or weight management effects. In clinical practice, patients who inadvertently store their GLP-1 medication in warm conditions may notice suboptimal glycaemic control or reduced therapeutic benefit.

Freezing is equally problematic. If a GLP-1 pen is accidentally frozen, the medication should not be used, even after thawing. Freezing causes irreversible damage to the protein molecules, and there is no official guidance supporting the safety or efficacy of previously frozen GLP-1 products. If you suspect your medication has been frozen—for example, if it was stored too close to the freezer compartment or left in a cold car overnight in winter—do not use it. Contact your healthcare provider for advice.

Prolonged exposure to light can also degrade GLP-1 medications, which is why they are supplied in opaque or light-protective packaging. Keeping the pen cap on when not in use provides additional protection.

If your GLP-1 medication has been stored incorrectly, do not assume it is still safe to use. Contact your GP surgery or community pharmacist for advice. They may recommend disposing of the affected pen and obtaining a new prescription. Never attempt to use medication that has been compromised, as this could lead to inadequate disease control. Always check your product's patient information leaflet for specific guidance on what to do if storage conditions have been breached.

Storage Guidelines for Opened and Unopened GLP-1 Pens

Clear storage guidelines help patients maximise the shelf life and safety of their GLP-1 medications. The following recommendations are based on MHRA-approved product information and manufacturer instructions.

For unopened GLP-1 pens:

• Store in the refrigerator at 2°C to 8°C

• Keep in the original carton to protect from light

• Do not freeze; if frozen, discard the pen

• Check the expiry date regularly and do not use beyond this date

• Store away from the freezer compartment and avoid the fridge door where temperatures fluctuate

• Some products allow limited room-temperature storage before first use (e.g., Trulicity up to 30°C for 14 days; Bydureon up to 30°C for 4 weeks)

For opened (in-use) GLP-1 pens:

• Multi-dose pens (Ozempic, Victoza, Saxenda, Byetta) have specific in-use storage requirements:
• Ozempic: Up to 6 weeks at temperatures up to 30°C or refrigerated
• Victoza/Saxenda: Up to 1 month at temperatures up to 30°C or refrigerated

• Byetta: Up to 30 days at temperatures up to 25°C

• Write the date of first use on multi-dose pen labels

• Single-use pens (Wegovy, Trulicity) should be discarded after injection

• Bydureon must be used immediately after reconstitution

• Keep the pen cap on when not in use to protect from light

• Do not store with the needle attached, as this can cause air bubbles, leakage, or contamination

• Avoid exposure to direct sunlight or heat sources (e.g., radiators, car dashboards)

• If travelling, store in a cool bag with ice packs (ensure the pen does not come into direct contact with ice)

General safety advice:

• Always inspect the medication before each injection (see next section)

• Dispose of used pens in a sharps container according to local NHS guidelines

• If you are unsure whether your pen has been stored correctly, do not use it—seek advice from a healthcare professional

• Keep all medications out of the sight and reach of children

Patients should familiarise themselves with the specific storage instructions for their prescribed GLP-1 product, as requirements vary significantly between brands. Your community pharmacist can provide tailored advice and supply appropriate storage accessories if needed.

Signs Your GLP-1 Medication May No Longer Be Safe to Use

Before each injection, it is essential to visually inspect your GLP-1 medication to ensure it remains safe and effective. Even when stored correctly, certain changes in appearance or condition indicate that the medication should not be used.

Key warning signs include:

• Discolouration: Most GLP-1 solutions should be clear and colourless or slightly yellowish (depending on the product). If the liquid appears cloudy, darkened, or has changed colour, do not use it. Exception: Bydureon forms an opaque white/off-white suspension after reconstitution; it should appear even and milky without clumps or unmixed powder.

• Particles or sediment: For clear solution products, the presence of visible particles, crystals, or floating matter suggests contamination or degradation. The solution should be free from particulate matter.

• Cloudiness or turbidity: Most GLP-1 formulations (except Bydureon) should be clear. Cloudiness may indicate bacterial contamination or protein aggregation.

• Damaged pen or packaging: Cracks, leaks, or damage to the pen device can compromise sterility and dosing accuracy.

• Expired in-use period: If more than the recommended period has passed since first use (e.g., 6 weeks for Ozempic, 1 month for Victoza/Saxenda, 30 days for Byetta), the pen should be discarded regardless of appearance.

• Past expiry date: Never use medication beyond the expiry date printed on the label, even if it has been stored correctly.

What to do if you notice any of these signs:

If your GLP-1 medication shows any of the above warning signs, do not inject it. Dispose of the pen safely in a sharps bin and contact your GP surgery or pharmacy to obtain a replacement. If you have already missed a dose due to unusable medication, follow the missed dose guidance in your patient information leaflet or contact your healthcare team for advice.

When to seek medical advice:

If you have accidentally injected medication that appeared abnormal, or if you develop unexpected symptoms such as severe injection site reactions, allergic symptoms (rash, swelling, difficulty breathing), or signs of infection, contact your GP or NHS 111 immediately. In case of a serious allergic reaction, call 999.

If you experience any side effects, talk to your healthcare professional. This includes any possible side effects not listed in the package leaflet. You can also report side effects directly via the Yellow Card Scheme at yellowcard.mhra.gov.uk or search for MHRA Yellow Card in the Google Play or Apple App Store.

Regular inspection of your GLP-1 medication is a simple but vital step in ensuring safe and effective treatment. If you have any concerns about the appearance or storage of your medication, always seek professional guidance rather than taking risks with your health.

Frequently Asked Questions