Why You Should Discard Open Vials After 28 Days—Even If There’s Medicine Left

If you’ve ever looked at your medication—whether it’s a multi-use vial of GLP-1 medication or one of the injectable supplements we offer like B12, biotin, or lipo-shot—and thought, “This still looks fine… I don’t want to waste it,” you’re not alone. We totally get it! These medications are valuable, and throwing away something that seems perfectly usable can feel counterintuitive.

But there’s a very good reason why manufacturers—and your Flow Wellness provider—recommend discarding open vials after 28 days. It’s all about keeping you safe and making sure every dose you take remains as effective, stable, and clean as it’s meant to be.

Does the Medication Suddenly “Go Bad” on Day 28?

Not exactly. It doesn’t turn toxic or spoil overnight—but after 28 days, two important things can start to happen:

1. The Risk of Contamination Increases

Once a vial is punctured—even just once—it’s no longer in a sealed, sterile environment. Every time a needle enters the vial, even with proper technique, there’s a small chance of introducing bacteria. Over time, and with repeated access, that risk grows. If contamination occurs, it could result in injecting bacteria directly into your body, which—even though rare—can lead to serious infections and illness.

Preservatives (if included in the vial) may help, but their effectiveness also diminishes over time, especially once the seal is broken. Please note that single use vials (Zepbound) should be discarded after one use.

2. It’s Not Just About Sterility—It’s Also About Stability.

GLP-1 medications are peptide-based, which means they’re especially sensitive to air, light, and temperature changes. Even when stored correctly, these compounds can begin to break down after 28 days. The same goes for injectable supplements like B12, biotin, and lipo shots.

What does this mean for you?

• Your medication may become less effective

• Your body may not absorb or respond to it as intended

• You may not get the full therapeutic benefit you’re expecting

These changes aren’t always visible—there’s often no color change, cloudiness, or smell—but the integrity of the medication can still be compromised.

So, while the medication doesn’t become dangerous on day 28, it does become less reliable and predictable, and that’s not a risk worth taking.

Is This Just a Manufacturer Rule?

Not at all. This is a widely accepted best practice in healthcare. Organizations like the CDC, USP (United States Pharmacopeia), and the World Health Organization all support discarding multi-use vials 28 days after first puncture—unless the manufacturer specifically states otherwise

Why We Follow This Guideline at Flow Wellness

At Flow Wellness, your safety and results are our top priorities. We follow evidence-based medication handling guidelines to ensure you’re getting the highest-quality care with the most reliable outcomes. Even when it means tossing a bit of unused medicine, it’s worth it to protect your health and ensure every dose is working as intended.

This Isn’t Just About Rules—It’s About Results

We’re not being rigid—we’re protecting your progress. Whether you’re using GLP-1 medications for weight loss or supplements to support energy and metabolism, staying consistent and safe with your dosing is key to getting the best results and avoiding set-backs.

We Understand: You Don’t Want to Waste What You Paid For

We hear this all the time, and we completely understand! These medications are valuable and are an investment in your health—and of course you want to get the most out of every vial. If you’re consistently left with leftover medication, let’s talk. We may be able to:

• Adjust your dosing schedule

• Explore smaller vial sizes

• Make sure you’re drawing up accurate doses

Pro tip: Vials are often slightly overfilled by the manufacturer. Even if you use every scheduled dose, a little bit of liquid might be left—and that’s normal. That extra is not intended for use beyond 28 days.

Tips to Get the Most Out of Each Vial (Safely)

• Label the vial with the date you first opened it

• Use a clean, sterile needle and syringe each time

• Store in the refrigerator (never freeze)

• Keep the vial upright and tightly sealed

• Discard after 28 days, no matter how it looks

Need Support? We’re Here for You

If you have questions about your medication, GLP-1 dosing, supplements, or safe storage practices, we’re just a call or message away.

Learn more here:

• Doctor Q&A: Common Questions About GLP-1 Medications Answered
• How to Fix Hair Loss: Proven Strategies That Really Work
• Top 4 Peptides You Should Know About