# Zepbound: a five-day half-life, 2.5 mg steps and your shot day > Zepbound (tirzepatide) half-life is about 5 to 6 days per the label. Track your weekly shot, 2.5 mg step-ups, the 4-day missed-dose window and sites in Peppy. Source: https://peppytracker.com/compounds/tirzepatide-zepbound/ Last updated: 2026-08-30 Zepbound is Eli Lilly's once-weekly tirzepatide pen approved for chronic weight management and obstructive sleep apnea, a dual GIP/GLP-1 agonist titrated in 2.5 mg steps up to 15 mg. The Peppy catalog lists it as a pen dosed in mg, weekly, half-life about 120 hours. Peppy keeps the shot day, advances the steps and ties weight and side effects to each dose. ## Tracking Zepbound: what matters The Zepbound half life is about 5 to 6 days per the label, which is why one shot a week holds a steady level and why the label's missed-dose window is 4 days. Peppy's "active in your system" chart uses the catalog's 120-hour figure to estimate that level; it is not a measurement, but it makes the weekly rhythm visible. The [how-long-it-stays guide](https://peppytracker.com/guides/how-long-does-semaglutide-stay-in-your-system/) covers the semaglutide equivalent and how to read the curve. For a weight-management protocol the tracking that pays off is the pairing of dose and outcome. Zepbound's ladder runs 2.5 to 15 mg in 2.5 mg steps, each held at least 4 weeks on the label. Dose step-ups (Pro) put your prescriber's version on the calendar, and Progress (Pro insights) marks every step-up on your weight trend, with weight read from Apple Health and every weigh-in written back. Nausea, food noise and appetite get a 1-to-5 rating in the daily check-in and show up as a heat-map next to the doses. The [weight tracker guide](https://peppytracker.com/guides/glp-1-weight-tracker-apple-health/) shows what that looks like after two months. Pens are single-dose, so inventory (Pro) is pens times one, with a refill reminder before the box runs out. The body map rotates abdomen, thighs and upper arms, the three areas the label lists. ## Schedule and cycles The Peppy catalog lists Zepbound as weekly with a dose ladder of 2.5, 5, 7.5, 10, 12.5 and 15 mg (catalog listing, not a recommendation). The label describes one shot a week on the same day, any time, with or without meals; a missed shot is taken within 4 days or skipped; the weekday can move if shots stay 72 hours apart. Peppy computes missed and overdue from the schedule, never stores them, so a late shot is one entry on the day it happened. There is no cycling on the label. Pause the protocol if your prescriber stops you, and resume without the calendar filling up with missed dots. ## How to do this in Peppy 1. Open **Protocols**, tap **+**, search "Zepbound". The catalog sets pen, mg, weekly and the half-life. 2. Enter the current dose, weekday and time. 3. Add rungs under **Dose step-ups** (Pro) with a duration for each. 4. Enter pens in **Inventory** (Pro), one dose per pen. 5. On shot day, tap the countdown on **Today**, choose the suggested site on the body map and log. Turn on **Settings > Reminders** (Pro). 6. Weigh in and do the **check-in** daily; open **Progress** before appointments and **Export** (Pro) a PDF for your prescriber. The [Zepbound tracker page](https://peppytracker.com/trackers/zepbound-tracker/) has the weekly routine in full. ## Frequently asked ### What is the Zepbound half life? The Zepbound label reports an elimination half-life of approximately 5 to 6 days in patients with overweight or obesity. The Peppy catalog lists 120 hours and uses it for the "active in your system" chart, an estimate for timing rather than a measurement. ### What if I miss a Zepbound shot? The label says to take the missed dose as soon as possible within 4 days (96 hours), otherwise skip it and take the next dose on the regular day. Peppy shows the missed shot and the next due date so you can talk to your prescriber with the facts. See the [missed dose guide](https://peppytracker.com/guides/missed-glp-1-dose/). ### How does the Zepbound dose step-up work? The label starts at 2.5 mg weekly for 4 weeks, then 5 mg, and may increase in 2.5 mg increments after at least 4 weeks on the current dose, up to 15 mg. Peppy's dose step-ups (Pro) model that ladder. Your prescriber sets the steps. ### Can I change my Zepbound shot day? The label allows the day to change as long as the two doses are at least 3 days (72 hours) apart. Edit the weekday on the protocol in Peppy; upcoming shots move, past logs stay. ### Where do you inject Zepbound? The label lists abdomen, thigh or upper arm, rotating sites. Peppy's body map suggests the next site and shows "last used 7 days ago". See the [rotation guide](https://peppytracker.com/guides/injection-site-rotation/). ### How long does Zepbound stay in your system? The Peppy catalog lists a half-life of about 5 days for Zepbound. After roughly five half-lives, about 3.6 weeks, most of a single dose has cleared. That is an estimate from the half-life, not a measurement, and individual clearance varies. ### Can I track Zepbound in Peppy? Yes. Zepbound is one of 123 compounds built into Peppy, with its form, unit and typical frequency prefilled. Add it as a protocol, set your schedule, and Peppy handles the countdown, the log and the reminders (Pro). ### Where should I inject Zepbound? Follow your prescriber's instructions. For subcutaneous shots the GLP-1 labels list the abdomen, thigh and upper arm and say to rotate. Peppy's body map has 13 sites, suggests the next one, and shows when each was last used. Read the [site rotation guide](https://peppytracker.com/guides/injection-site-rotation/). --- Peppy is a tracking tool, not medical advice. Dose calculations are mathematical conversions only. Always follow your prescriber's instructions and verify every draw-up yourself. Peppy is a free iPhone app (Pro subscription optional). App Store: https://apps.apple.com/us/app/peptide-tracker-peppy/id6775005514