What Is Zepbound Made Of? A Guide to Zepbound’s Ingredients and How It’s Made

Tirzepatide is the primary ingredient in Zepbound, an injectable medication for weight loss and obstructive sleep apnea. But tirzepatide isn’t its only ingredient. Several others help keep Zepbound stable and working the way it’s supposed to.

What are Zepbound’s ingredients? And how is it made?

What is the active ingredient in Zepbound?

Tirzepatide is the active ingredient in Zepbound. Once injected, it acts like two natural gut hormones:

• Glucose-dependent insulinotropic polypeptide (GIP)

• Glucagon-like peptide-1 (GLP-1)

Tirzepatide works in certain areas of your brain that help regulate appetite and food cravings. It also slows the movement of food through your digestive tract, helping you feel full faster and for longer. And it might counteract certain hunger hormones that play a role in weight gain.

Beyond this, tirzepatide also tells your pancreas to release more insulin after you eat. And it signals your liver to make less new glucose (sugar). This is why tirzepatide is also approved to treat Type 2 diabetes under the brand name Mounjaro.

What other ingredients make up Zepbound?

Zepbound has only one active ingredient (tirzepatide). But it has several inactive ingredients. These substances don’t affect how tirzepatide works in the body. They generally help maintain Zepbound’s shelf life and stability. They also help reduce pain during injection.

Zepbound comes as single-dose pens and vials, as well as multi-dose pens (Zepbound KwikPens). The inactive ingredients are slightly different, depending on if you're using a single-dose or multi-dose version of Zepbound.

Single-dose versions of Zepbound contain the following inactive ingredients:

• Sodium chloride (makes injections less painful)

• Sodium phosphate dibasic heptahydrate (buffer to keep Zepbound stable)

• Water for injection (carries tirzepatide into your body)

• Hydrochloric acid (adjusts acidity)

• Sodium hydroxide (adjusts acidity)

Zepbound KwikPens contain the following inactive ingredients:

• Benzyl alcohol (preservative to prevent germs from growing)

• Glycerin (makes injections less painful)

• Phenol (preservative to prevent germs from growing)

• Sodum chloride

• Sodium phosphate dibasic heptahydrate

• Water for injection

• Hydrochloric acid

• Sodium hydroxide

Can any ingredients in Zepbound cause an allergic reaction?

Yes. It’s possible to have an allergic reaction to any of Zepbound’s active or inactive ingredients. This is very rare. But allergic reactions can be serious or even life-threatening. If you have allergies, make sure to review these with your prescriber and pharmacist before starting Zepbound.

If you experience allergic reactions, such as hives or a rash, contact your prescriber right away. If you have any symptoms that seem severe, such as trouble breathing, call 911 or go to the ER.

How is Zepbound made?

Zepbound is made using a process called hybrid solid-phase peptide synthesis/liquid-phase peptide synthesis (SPPS/LPPS). This process takes amino acids (protein building blocks) and puts them in a certain order to form tirzepatide. Once formed, scientists purify and freeze dry tirzepatide to create the final version that’s placed into Zepbound pens and vials.

Natural GIP and GLP-1 hormones only last for a few minutes in your body before it’s broken down. But the SPPS/LPPS process produces tirzepatide, a molecule that’s designed to resist rapid breakdown, keeping it active for much longer. This is why you have to inject Zepbound only once a week.

How to save on Zepbound

There are ways to save on Zepbound, which is available as a brand-name medication. If you have commercial insurance, you may be eligible to pay as little as $25 for a 1- or 3-month supply of Zepbound pens through the manufacturer’s copay savings program.

If your plan doesn’t cover Zepbound, you may still be able to save. Lower-cost single-dose vials and KwikPens are available through LillyDirect for $299 (2.5 mg), $399 (5 mg), and $449 (7.5 mg, 10 mg, 12.5 mg, and 15 mg) per month. You can also access Zepbound KwikPen through GoodRx starting at $299 per month.

What's more, subscribers to GoodRx for Weight Loss can access FDA-approved, brand-name GLP-1 medications like Zepbound.

Why trust our experts?

Written by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Our editorial standards

Meet our experts