OptiPin
GLP-1 level plotter
See roughly how much semaglutide, tirzepatide, dulaglutide, liraglutide or retatrutide is in your system week by week through each titration step. It also shows what one late or missed dose does to that curve. Built on the half-lives in each drug's prescribing information.
Starts on the label ladder. Edit it to match your own steps, separated by commas.
Longer gaps can mean restarting at a lower dose. That is your prescriber's call, not this chart's.
Week-by-week table
| Week | Dose | End of week | Highest that week |
|---|
Log your shots, see your curve in OptiPin
OptiPin plots GLP-1 levels from the doses you actually logged, reminds you of the weekly shot and keeps your weight, side effects and titration steps in one timeline. On-device, no account needed.
Download on the App StoreWhy each titration step takes about a month to settle
Steady state takes four to five half-lives. With weekly shots, each dose lands on what is left of the last one, so the level climbs for several weeks before it levels off. Semaglutide's half-life is about a week, so the Ozempic label puts steady state at 4 to 5 weeks. Tirzepatide's is about 5 days, so the Mounjaro label says 4 weeks. Dulaglutide (Trulicity) also sits around 5 days, with steady state in 2 to 4 weeks.
That is why labels hold each step for at least 4 weeks. Step up sooner and the next increase starts before the last one has finished building. The plot shows this as a staircase: every step rises for a few weeks, then flattens.
At steady state there is more in your body than one dose. With a one-week half-life and weekly shots, the model settles at roughly twice the peak of a single dose, because half of each shot is still there when the next one goes in. Tirzepatide's shorter half-life gives a little less build-up.
Liraglutide is the exception. Its half-life is about 13 hours, so Saxenda is taken daily and each weekly step settles within a few days rather than a month.
What a late or missed dose does
Because the half-life is long, one late weekly shot dips the curve rather than emptying it. With semaglutide, the level a week after a missed dose is still around half of where it would have been. Pick One dose late or Missed doses above and the plot draws your scenario next to the on-schedule curve, with how low it goes and when it catches up.
Each label has its own window for taking a late dose, shown in the box above the table for the medication you pick. Outside that window the labels say to skip it and carry on with the usual day, rather than doubling up. A dip after missed weeks is also why some people notice appetite or side effects shift. It is also the reason restarting after a longer break is something to agree with your prescriber.
Frequently asked questions
What is the half-life of Mounjaro (tirzepatide)?
About 5 days, according to the Mounjaro prescribing information, which is what makes once-weekly dosing work. The label puts peak levels 8 to 72 hours after a shot and steady state at about 4 weeks. Five half-lives, the usual mark for "mostly gone", is about 25 days after the last dose.
How long does Ozempic stay in your system?
Semaglutide has a half-life of about a week. The Ozempic label says it is present in the circulation for about 5 weeks after the last dose. Wegovy is the same molecule, so the same timing applies.
When does semaglutide reach steady state?
After 4 to 5 weeks of weekly dosing on the same dose, per the Ozempic label. Each titration step starts that clock again, which is why the plot looks like a staircase.
What is the half-life of retatrutide?
About 6 days in the phase 1b trial (Urva et al., Lancet 2022). Retatrutide is investigational and has no approved label, so its steps here (2, 4, 6, 9 and 12 mg, four weeks apart, from the 12 mg arm of the phase 3 TRIUMPH-1 trial) are only an example.
Is this my blood level?
No. It is the estimated amount of drug in the body from a one-compartment model, in mg. Turning that into a blood concentration would need a volume of distribution, your weight and a lab assay. It is useful for the shape and timing of the curve, not for a number to act on.
What happens to my levels if I miss a dose?
The curve drops for a week or two and then climbs back once regular shots resume. Choose Missed doses above to see by how much for your medication and step. For what to actually do about a missed dose, follow your label's window or ask your prescriber.
Related tools
- GLP-1 titration schedule: the label ladder mapped to dates from your start day.
- GLP-1 pen click charts: how dial-a-dose pens count clicks.
- Half-life calculator: the same model for 65 compounds, at steady state or from a single dose.
- Trackers: Ozempic, Wegovy, Mounjaro, Zepbound, Trulicity, Victoza and Saxenda, retatrutide.
- Retatrutide dosing guide: how the trials stepped doses up.
- GLP-1 protein calculator – daily and per-meal protein to protect lean mass.
Sources
- Ozempic (semaglutide) – DailyMed label: half-life about 1 week, peak 1 to 3 days, steady state 4 to 5 weeks, missed-dose window 5 days.
- Wegovy (semaglutide) – DailyMed label: titration, maintenance doses and missed-dose rule.
- Mounjaro (tirzepatide) – DailyMed label: half-life about 5 days, peak 8 to 72 hours, steady state 4 weeks, missed-dose window 4 days.
- Zepbound (tirzepatide) – DailyMed label
- Trulicity (dulaglutide) – DailyMed label: half-life about 5 days, peak 24 to 72 hours, steady state 2 to 4 weeks.
- Victoza (liraglutide) – FDA prescribing information: half-life about 13 hours, peak 8 to 12 hours.
- Saxenda 6 mg/mL – Summary of Product Characteristics (emc, UK): daily titration and missed-dose rule.
- Urva S, et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. Lancet. 2022;400(10366):1869–1881.
- Eli Lilly – Lilly's triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial (May 21, 2026): TRIUMPH-1 escalation from 2 mg every four weeks to 4, 9 or 12 mg.