Tirzepatide / Guide
Zepbound vials vs pens: single-dose, multi-dose and KwikPen compared
Zepbound now comes four ways in the US. The medicine and doses are the same in each. What changes is the volume, what else you need, and how long it keeps.
[00] Short answer
- Zepbound (tirzepatide) comes as a single-dose pen, single-dose vial, multi-dose vial and KwikPen, each in 2.5 to 15 mg strengths1.
- Single-dose pens and vials hold one dose in 0.5 mL. Multi-dose vials and KwikPens hold 4 weekly doses of 0.6 mL1.
- Vials need a syringe and needle, bought separately; the label gives a 1 mL syringe as an example. KwikPens need pen needles. Single-dose pens need nothing extra1,3–5.
- Out of the fridge: single-dose pens and vials keep up to 21 days in total. Multi-dose vials and KwikPens are thrown away 30 days after first use or after 4 doses1.
What's the difference between Zepbound vials, pens and the KwikPen?
All four Zepbound presentations hold the same tirzepatide in the same six weekly doses, 2.5 mg to 15 mg1. They differ in how many doses each one holds, how much liquid each dose is, and what you need to inject it.
| Single-dose pen | Single-dose vial | Multi-dose vial | KwikPen | |
|---|---|---|---|---|
| Doses in each | 1 | 1 | 4 (one a week) | 4 (one a week) |
| Volume per dose | 0.5 mL | 0.5 mL | 0.6 mL | 0.6 mL |
| How the dose is set | Fixed, automatic | You draw it up | You draw it up | Turn the knob until it stops |
| Also needed | Nothing | New syringe and needle each time | New syringe and needle each time | New KwikPen-compatible pen needle each time |
| Priming | No | No | No | Before every weekly injection |
| US carton | 4 pens | 1 or 4 vials | 1 vial | 1 KwikPen |
Sources: section 16.1 for cartons1, and each Instructions for Use for supplies and priming2–5.
The label asks prescribers to tell you which presentation you'll get, train you on it, and retrain you if it changes1. It also says the KwikPen isn't recommended for people with vision problems to use on their own1.
Zepbound vial strengths: how many mg per mL?
A single-dose Zepbound vial or pen holds the full dose in 0.5 mL, for example 5 mg/0.5 mL. A multi-dose vial or KwikPen holds four doses in 2.4 mL, for example 20 mg/2.4 mL for four 5 mg doses1.
| Weekly dose | Single-dose pen or vial | Multi-dose vial or KwikPen |
|---|---|---|
| 2.5 mg | 2.5 mg/0.5 mL | 10 mg/2.4 mL (4.17 mg/mL) |
| 5 mg | 5 mg/0.5 mL | 20 mg/2.4 mL (8.33 mg/mL) |
| 7.5 mg | 7.5 mg/0.5 mL | 30 mg/2.4 mL (12.5 mg/mL) |
| 10 mg | 10 mg/0.5 mL | 40 mg/2.4 mL (16.7 mg/mL) |
| 12.5 mg | 12.5 mg/0.5 mL | 50 mg/2.4 mL (20.8 mg/mL) |
| 15 mg | 15 mg/0.5 mL | 60 mg/2.4 mL (25 mg/mL) |
Each multi-dose strength holds 4 doses of 0.6 mL. The mg/mL figures match the label's section 3 table1.
Because the strength changes with the dose, the volume stays the same whatever your dose: always 0.5 mL from a single-dose vial and always 0.6 mL from a multi-dose vial3–4. If you move between them, the mg dose can stay the same while the mL changes.
What syringe do you need for Zepbound vials?
Zepbound vials don't come with syringes or needles. The label says to use a syringe that can measure the dose, "e.g., a 1 mL syringe capable of measuring a 0.5 mL or 0.6 mL dose", and a new syringe and needle for every injection1.
- Single-dose vial: draw 0.5 mL of air, push it into the vial, then draw to the 0.5 mL line3. Throw the vial away after use, even if medicine is left3.
- Multi-dose vial: the same steps with 0.6 mL4. Use a new syringe and needle for each of the 4 doses4.
- Injecting: keep the needle in your skin for at least 5 seconds after pushing the plunger down, so the full dose goes in3–4.
The label doesn't name a type of syringe beyond the example, and your healthcare provider recommends the one to use3–4. If yours is marked in units (U-100), each unit is 0.01 mL, so 0.5 mL is the 50-unit line and 0.6 mL is the 60-unit line. See how to read an insulin syringe.
[Tool]Check mL against syringe unitsReads 0.3, 0.5 and 1 mL syringesHow does the Zepbound KwikPen work?
The Zepbound KwikPen is a disposable pen holding 4 fixed weekly doses of one strength. You attach a new pen needle, prime it, then turn the dose knob all the way until it stops to set your dose5.
- Prime every week: turn the knob 2 clicks to the prime position and push out a drop with the needle pointing up, before each injection5.
- Don't count clicks to set the dose. Turn until the knob stops and the dose icon shows in the window5.
- Hold for 5: push the knob in until it stops and slowly count to 5 before removing the needle5.
- After 4 doses, throw the pen away even if medicine is left. The pen stops you dialing a full fifth dose. Don't inject the leftover or move it into a syringe5.
The single-dose pen is simpler: pull off the base cap, place it on your skin, unlock, and press for up to 10 seconds. A first click means the injection started and a second click means it's done2.
How do you store Zepbound vials and pens?
Keep every Zepbound presentation in the fridge at 2°C to 8°C (36°F to 46°F), in its carton, and never freeze it1. The rules for room temperature differ between single-dose and multi-dose.
| Single-dose pen or vial | Multi-dose vial or KwikPen | |
|---|---|---|
| In the fridge | Store here until use | Unopened: usable until the expiry date on the label |
| At room temperature, up to 30°C (86°F) | Up to 21 days in total | Unopened: throw away after 30 days |
| After first use | Single use, then throw away | Fridge or room temperature, in the carton |
| Throw away | After use, or after 21 days at room temperature | After 4 doses, 30 days after first use, or 30 days at room temperature, whichever comes first |
For a pen or vial left out too long or frozen, see left out overnight or frozen.
Can you get Zepbound vials in the UK?
No. In the UK, tirzepatide is sold as Mounjaro, and the UK medicines list (eMC) shows it only as KwikPens, each holding 4 doses6–7. See Mounjaro pen doses in the UK and Mounjaro vs Zepbound.
We haven't included prices, because Lilly's own price pages couldn't be checked for this guide.
Questions
Are Zepbound vials the same medicine as the pens?
Yes. Every Zepbound presentation contains tirzepatide in the same 2.5 mg to 15 mg weekly doses. Single-dose vials and pens give the dose in 0.5 mL; multi-dose vials and KwikPens give it in 0.6 mL.
Do Zepbound vials come with syringes?
No. The vial instructions say the needle and syringe are supplied separately. The label gives a 1 mL syringe that can measure 0.5 mL or 0.6 mL as an example, with a new syringe and needle for each injection.
How many units is a Zepbound single-dose vial?
The label gives the dose as 0.5 mL, not units. On a U-100 syringe marked in units, 0.5 mL is the 50-unit line. A multi-dose vial dose is 0.6 mL, the 60-unit line.
Can I get a fifth dose out of a Zepbound KwikPen or multi-dose vial?
No. The label says to throw them away after 4 weekly doses, even if medicine is left. The KwikPen instructions say not to inject leftover medicine or transfer it into a syringe.
How long can a Zepbound vial be out of the fridge?
A single-dose vial can be kept at up to 30°C (86°F) for a total of 21 days. An opened multi-dose vial is thrown away after 30 days at room temperature, 30 days after first use, or after 4 doses.
Do I need to prime a Zepbound KwikPen every time?
Yes. The KwikPen instructions say to prime before each weekly injection, with a new pen needle each time. Single-dose pens and vials don't need priming.
Sources
Checked against Zepbound US prescribing information (revised 08/2026) and its four Instructions for Use (single-dose pen, single-dose vial, multi-dose vial and KwikPen, 2026). How we check
- 1Zepbound (tirzepatide) injection, US prescribing information, Eli Lilly (DailyMed, revised 08/2026). sections 2.4, 3, 16.1 and 16.2
- 2Zepbound single-dose pen, Instructions for Use (revised April 2026). steps 2 to 4
- 3Zepbound single-dose vial, Instructions for Use (revised April 2026). supplies, steps 7 to 15, and storage
- 4Zepbound multi-dose vial, Instructions for Use (revised January 2026). supplies, steps 7 to 15, and storage
- 5Zepbound KwikPen, Instructions for Use (revised January 2026). priming, steps 7 to 17, storage and troubleshooting
- 6Mounjaro KwikPen solution for injection in pre-filled pen, UK SmPC (eMC). sections 1 and 6.5; updated on eMC 8 Sep 2026
- 7eMC: search results for Mounjaro (UK product list). accessed 8 Nov 2026
This guide explains what labels and published studies say. It isn't medical advice and doesn't replace your prescriber or pharmacist.
Spotted a mistake or something out of date? Tell us. We aim to fix factual errors within two working days.
Read next
- TirzepatideTirzepatide is a once-weekly injection sold as Mounjaro and Zepbound. Label doses run from 2.5 mg up to 15 mg. Compounded vials are not FDA-approved.
- Tirzepatide dosage chart: mg, mL and unitsPrescriptions say mg and syringes say units. This chart lines up each Mounjaro and Zepbound label dose with its mL and U-100 units.
- Mounjaro vs ZepboundSame medicine, same doses, same pens and vials. The difference is what each one is approved for, and in the UK there's only Mounjaro.