Key takeaways
- Each dose adds its own rise-and-fall curve. The plot is the sum.
- A half-life is the time for an amount to halve.
- Longer half-lives mean more overlap, so a steadier baseline.
- The curve is an estimate from published figures, not a measurement.
What this tool does
The plotter draws an estimated amount in the body over weeks, from the doses you give and the medicine's published absorption and elimination half-lives. It shows when a level rises, peaks, and fades, and what happens when doses overlap or the schedule changes.
It is a model. It is not a blood test, and it cannot tell you how you will feel.
How the arithmetic works
A common simple model gives each dose D a curve over time t since the injection:
A(t) = D × ka ÷ (ka − ke) × (e−ke·t − e−ka·t)
where ke = ln 2 ÷ elimination half-life and ka = ln 2 ÷ absorption half-life. Each dose is added at its injection time, and the total at any moment is the sum of all earlier doses. The curve starts at zero, rises as the dose is absorbed, then falls as it is cleared.
Elimination half-lives: semaglutide about 1 week, tirzepatide about 5 days, from the U.S. labels.
A worked example
Example. These numbers are made up to show the steps. They are not a label value and not a suggestion.
Made-up: a medicine whose amount halves every 5 days, given every 7 days. Just before dose 2, about 38% of dose 1 remains (0.57/5 ≈ 0.38). Before dose 3, about 38% of dose 2 plus 14% of dose 1. The remainder keeps stacking until each new dose adds as much as clears. That is a steady state.
What to check against your label
- The half-lives used, listed above.
- That the plot is relative to the dose, not to a concentration in your blood.
- That a change in dose or schedule is entered as it really happened.
Frequently asked questions
Can the plot tell me my dose?
No.
Why does the curve not match how I feel?
A model uses averages from published data. You are one person.
What is steady state?
The point where each dose adds as much as is cleared between doses.
How Reko does this in the app
Reko shows an estimated level from your own logged doses and the compound's published half-lives. It is labelled as an estimate, and your side effects and weight sit beside it, so you can look at them together.
Reko records what you and your prescriber decide. It never suggests a dose, and this page is not medical advice.
- Ozempic U.S. prescribing information (revised June 2026), DailyMed.
- Mounjaro U.S. prescribing information (revised July 2026), DailyMed.