Zepbound and Mounjaro Pen Clicks: What Each Click Means

On a Zepbound or Mounjaro single-dose pen, the first click means the injection has started and the second that it is complete (Zepbound pen instructions). A KwikPen clicks twice as you turn it to prime. The KwikPen dose is set by turning the knob to its stop, and "Do not count clicks as you select the dose" (KwikPen instructions).

Key facts

• The single-dose pen is pressed and held for up to 10 seconds, and the gray plunger shows when the dose is done (Zepbound Instructions for Use).
• A KwikPen is primed before every weekly injection (Zepbound KwikPen Instructions for Use).
• Each KwikPen gives 4 fixed doses of 0.6 mL and is thrown away after the fourth or 30 days after first use, whichever comes first (Zepbound label, section 16.2).
• The Ozempic pen’s instructions carry their own version: "Do not count the pen clicks" (Ozempic Instructions for Use).
• The liquid left in a KwikPen after its fourth dose keeps the pen working, and the pen will not dial a full dose from it (Lilly Medical).

What each click means

The two Lilly pens use their clicks for different jobs (single-dose pen instructions; KwikPen instructions).

Clicks on the single-dose pen

Press and hold the purple injection button for up to 10 seconds, then listen: the first click is the injection starting and the second is the injection completed (Zepbound Instructions for Use, single-dose pen). The injection is finished when the gray plunger is visible in the pen.

For a third, softer click, the pen’s instructions say: "Some people may hear a soft click right before the second loud click. That is the normal operation of the pen" (Zepbound Instructions for Use). Keep the pen on your skin until the second loud click.

KwikPen clicks and priming

The KwikPen holds 2.4 mL, four fixed weekly doses of 0.6 mL, like the Zepbound multi-dose vial (Zepbound label, sections 3 and 11). Its six strengths match the steps of the labeled dose ladder for Zepbound and Mounjaro, from 2.5 mg to 15 mg. In the US there is a Zepbound KwikPen and, for type 2 diabetes, a Mounjaro KwikPen (Mounjaro label, section 3). In the UK, the Mounjaro KwikPen covers type 2 diabetes and weight management (Mounjaro SmPC, section 4.1).

The clicks belong to priming, which the US instructions say to do before each weekly injection (Zepbound KwikPen Instructions for Use):

1. Turn the dose knob slowly until you hear 2 clicks and the extended line shows in the dose window. This is the prime position.
2. Hold the pen with the needle pointing up and tap the cartridge holder gently so air bubbles collect at the top.
3. Push the dose knob in until it stops and count slowly to 5. A drop of medicine at the needle tip means the pen is primed.
4. If no drop appears, repeat up to 2 more times, then change the needle and try once more, then call Lilly.

Then turn the knob all the way until it stops with the dose icon in the window, which is your weekly dose. To inject, push the knob in until it stops and count slowly to 5, and check that the icon still shows before you take the needle out.

After the fourth dose the pen will not let you dial another full dose. Throw it away with the medicine left in it, and never move that medicine into a syringe; the pen also goes in the trash 30 days after first use, whatever is left. Logging each shot with its date in Pensday keeps the day you started each pen on record, and those 30 days count from it.

What Lilly says about counting clicks

Community click charts assume a full KwikPen dose is about 60 clicks and divide the milligrams by that number to estimate a part dose. The 60-click figure appears in neither the US Zepbound KwikPen nor the UK Mounjaro KwikPen instructions, and the only click count either gives is the 2 clicks of priming. In a drawing that points at the marks printed on the cartridge, the UK instructions say "Do not use these marks as dose indicators" (Mounjaro KwikPen Instructions for Use).

Lilly Canada’s answer on splitting a KwikPen dose says the instructions "do not provide instructions for dialing a dose less than the full fixed dose" (Lilly Canada, splitting a Zepbound KwikPen dose). Lilly adds that it cannot make recommendations on splitting, because splitting has not been studied. Splitting a KwikPen dose is one form of taking less than a labeled GLP‑1 dose.

The Zepbound KwikPen instructions state that the pen meets the dose accuracy and functional requirements of ISO 11608-1, the standard for pen-injectors (Zepbound KwikPen Instructions for Use). The US Mounjaro KwikPen instructions carry the same "Do not count clicks" line at Step 11, where the dose is set on both pens (Mounjaro Instructions for Use). The Mounjaro click chart works through the community 60-click assumption at each UK KwikPen strength and labels it as an assumption.

If your Zepbound pen does not click

On the single-dose pen, check Step 3 of the instructions first: "Place the clear base flat against your skin at the injection site. Unlock by turning the lock ring." (Zepbound Instructions for Use, single-dose pen). Then press and hold the purple button. If the gray plunger is not visible afterwards, call Lilly on 1-800-545-5979 and store the pen safely until then.

The KwikPen instructions give these fixes (Zepbound KwikPen Instructions for Use):

• Knob hard to push: push more slowly, and if that fails, fit a new pen needle and prime again. Dust, food or liquid inside the pen means a new pen.
• Knob will not turn as far as the dose icon: throw the pen away, because there may not be enough medicine left for a full dose.
• Dose icon not showing after the injection: put the needle back in and finish the injection without redialing.
• Still unsure after that: do not start over or repeat the injection.

A drop of medicine on the KwikPen needle tip after the injection is normal and does not affect your dose. If you miss a dose altogether, a missed Zepbound dose can still be taken within 4 days of its day (Zepbound label, section 2.3).

Compounded click pens

If a compounding pharmacy has given you a pen set by counting clicks, what one click delivers depends on that pen and its concentration, and the pharmacy’s instructions are the reference. The compounded pen click calculator converts a dose into clicks for a pen where one click moves one unit on a U-100 scale, from the concentration on your label.

Compounded tirzepatide is not FDA-approved (FDA statement on compounding GLP‑1 drugs). A refill at a new strength changes the clicks for the same dose, as it changes the units drawn from a compounded vial. Ask the pharmacy to put the concentration and the amount per click in writing.