What’s the Difference Between Zepbound® Pens and Vials?

Published: 2025-05-05

Updated: 2025-05-06

4 mins

Zepbound® is an FDA-approved prescription medication that contains tirzepatide, a once-weekly injectable used to support chronic weight management in adults with obesity or certain weight-related health conditions. As part of a broader treatment plan that includes diet and exercise, it helps regulate appetite and improve metabolic function.

Zepbound® is available in two forms: prefilled, single-dose pens and multi-dose vials. While both deliver the same active ingredient, they differ in how they’re prepared, administered, and stored.

In this article, we’ll break down the key differences between Zepbound® pens and vials so you can feel more confident discussing the right option with your healthcare provider.

What is Zepbound® and How Does it Work?

Zepbound® (tirzepatide) is a prescription medication that belongs to a class of drugs known as GLP-1 and GIP receptor agonists. These receptors help regulate blood sugar levels, insulin response, and appetite. By mimicking the effects of two naturally occurring hormones – GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) – Zepbound® helps you feel full sooner and stay full longer, which can lead to reduced calorie intake over time.

When used alongside a reduced-calorie diet and increased physical activity, Zepbound® has been shown to support significant and sustained weight loss. It works through dual-action pathways, which may give it an edge over medications like semaglutide (found in Wegovy® and Ozempic®) that only target GLP-1.

Zepbound® is a brand-name prescription medication developed and sold by Eli Lilly and Company. As the manufacturer, Eli Lilly is the only source for the branded version of Zepbound®, and all prefilled pens and vials are distributed under their name.

Zepbound® is available only by prescription and should be used under the guidance of a licensed healthcare provider, especially since dosing and administration require medical supervision.

What is a Zepbound® Prefilled Pen?

The Zepbound® prefilled pen is a single-use, auto-injector designed to deliver a premeasured dose of tirzepatide once a week. Each pen contains one dose and is ready to use – there’s no need for mixing, measuring, or attaching needles. Patients simply select the injection site (like the stomach, thigh, or upper arm), activate the pen, and safely dispose of it after use.

This format is especially helpful for patients who are new to injections or prefer a more convenient, low-fuss option. Because it's similar in design to other auto-injectors like insulin pens, many patients find it familiar and easy to handle, even without prior experience.

Zepbound pens come in multiple strengths to align with the stepwise dosing schedule your provider may recommend. The design helps reduce the chance of dosing errors and supports a more seamless at-home experience.

What is a Zepbound® Vial?

The Zepbound® vial contains a single-dose liquid formulation of tirzepatide that must be drawn up with a syringe for each injection. Unlike the prefilled pen, the vial requires patients to measure their dose manually, using a sterile syringe and needle. This adds an extra step to the process but allows for more hands-on control over dosing.

Because it involves drawing medication from a vial and self-injecting, this option is typically better suited for patients who are already comfortable with injectable medications or those who are trained in proper technique. It may also be preferred by patients seeking a more cost-effective alternative, especially if their insurance doesn’t cover the branded prefilled pens.

While the vial option can be a practical choice, it does involve a learning curve for those unfamiliar with syringes or manual injections. Proper training and ongoing support from a healthcare provider are important to ensure safety and accuracy.

Key Differences Between Pens and Vials

Dosing

With Zepbound® prefilled pens, the dose is premeasured and built into the auto-injector, minimizing preparation time and reducing the risk of dosing errors. Pens are available in a full range of strengths – from 2.5 mg to 15 mg – to support standard dose escalation and maintenance.

In contrast, the Zepbound® vial contains multiple doses (2.5 mg, 5 mg, 7.5 mg, 10 mg) in liquid form and requires manual measurement with a syringe. While this offers some flexibility –  especially in how the medication is prepared and administered – it requires more training and precision to use safely at home.

Cost and insurance coverage

Zepbound® pens are dispensed through retail or specialty pharmacies and may be covered by insurance, depending on your plan. For eligible, commercially insured patients, a savings card may reduce the cost to as little as $25 per month.

Vials, on the other hand, are exclusively available as a self-pay option through LillyDirect™, Eli Lilly’s direct-to-patient pharmacy program. They cannot be billed through insurance and are not sold at regular pharmacies.

Vials currently start at $349/month for 2.5 mg and $499/month for higher doses, with special refill pricing if orders are placed within 45 days of the previous shipment. FSA and HSA cards are accepted, and injection supplies can be added at checkout for a small fee.

Storage and shelf life

Both forms must be refrigerated before use, but prefilled pens may have a longer shelf life at room temperature once taken out of the fridge, depending on manufacturer guidelines. Vials, once punctured, may have a limited window for safe use – typically 28 days – but this should be confirmed with your provider.

Which Option is Right for You?

Choosing between Zepbound® pens and vials depends on several personal factors, including your comfort level with injections, your budget, and whether you prefer the simplicity of a prefilled device or don’t mind the hands-on process of drawing up a dose from a vial. Both forms are equally effective when used as directed, so the best choice often comes down to what fits your routine and lifestyle.

It’s important to talk with your healthcare provider about which option aligns with your needs. If convenience or cost is a concern, they can help walk you through what’s available, including any savings programs or direct-purchase options. Telehealth visits can also be a helpful way to get started or follow up, especially if you’re new to weight loss medications or looking for guidance on proper use.

How Can Rex MD Help?

If you’re interested in Zepbound® or other brand-name GLP-1 medications Rex MD can help.

With the Rex MD Weight Management Program, you’ll gain access to branded GLP-1 medications along with clinical oversight, metabolic testing, and ongoing support from licensed healthcare providers, if you qualify. 

There’s no commitment to get started. See if you qualify to lose weight with Rex MD.