Semaglutide vs Tirzepatide: What to Track
The two main GLP-1 medication families differ in dosing units, titration steps and side effect timing — and those differences change what you should be logging.
Two families, one routine
Most people on GLP-1 treatment are taking one of two active ingredients. Semaglutide is the active ingredient in Ozempic® and Wegovy®. Tirzepatide is the active ingredient in Mounjaro® and Zepbound®. Both are typically weekly subcutaneous injections, and the day-to-day routine looks similar from the outside.
The differences that matter for tracking are in the numbers and the schedule, not in the routine.
This article is about record-keeping. Which medication is appropriate for you is a decision for you and your provider, and nothing here is a comparison of effectiveness or a recommendation of either.
Doses are not on the same scale
The single most common tracking mistake is treating the dose number as if it means the same thing across medications. It does not. Semaglutide and tirzepatide are dosed on completely different scales, and the numbers are not interchangeable in either direction.
Two practical consequences:
- Never compare your dose to someone else's unless they are on the same medication. "I'm on 5" means nothing without the drug name.
- If you switch medications, do not carry the old numbers forward in your log as if the series continues. Start a new series, or the chart becomes actively misleading.
Record the medication name alongside every dose, not just the number. It costs nothing and it is the field people most often wish they had.
Half-life differs, and it changes the shape of the week
Both are weekly injections, but they do not produce identical curves.
Semaglutide's half-life is roughly a week — around 165 hours. Tirzepatide's is roughly five days, around 120 hours. Both are long enough to support weekly dosing, which is the point, but the shorter half-life means levels fall somewhat further between shots.
| Semaglutide | Tirzepatide | |
|---|---|---|
| Half-life | ~7 days (165 h) | ~5 days (120 h) |
| Dosing | Weekly | Weekly |
| Time to steady state | ~4–5 weeks | ~3–4 weeks |
| Dose scale | Not comparable | Not comparable |
Two practical consequences for tracking. The first is that the trough at the end of the week may be more pronounced on tirzepatide, so if you are logging appetite or food noise against day-of-cycle, expect the shape to differ.
The second is that levels take a somewhat shorter time to plateau after a change, which slightly shifts when a new dose can fairly be judged. Both take weeks rather than days, which is the part that matters — the half-life explainer covers why the week after an increase is rarely the worst one.
These are population averages, not measurements of you. They describe the general shape of a cycle, not your blood.
Titration schedules differ
Both families are titrated upward over months, but the step sizes and intervals are not the same, and they vary further between the branded products within each family.
This is why a generic dose-escalation chart found online is a poor substitute for writing down the plan your provider actually gave you. Track your own schedule; the fact that a friend on a different product stepped up at a different point is not evidence about yours.
Side effect timing is worth logging separately
Gastrointestinal side effects — nausea, reflux, constipation, appetite change — are common to both families, and for both, they tend to cluster after an injection and after a dose increase.
What varies is the individual pattern: which symptoms, how intense, how long they take to settle. That variation exists between two people on the same medication as much as between the two families. Your own log is the only thing that tells you about your own pattern; the general profile of the drug does not.
If you switch between families, log the transition explicitly. The first few weeks on a new medication are not comparable to the last few weeks on the old one, and a chart that runs them together will suggest a trend that is not there.
Pens, vials and units
Delivery differs across products and across brand versus compounded forms — prefilled pens with fixed dose steps, pens with a dial, vials drawn with a syringe. Vials in particular mean converting between milligrams and units at a given concentration, which is an easy place to make a mistake.
If your product involves that conversion, record both numbers: the dose your provider prescribed and the volume you actually drew. If they ever disagree, you want to be able to see it.
Switching between the two
Switching is common enough — for tolerability, for cost, for supply — that it is worth knowing what it does to your record before it happens.
Three things to do at the switch:
Mark the date explicitly. Not as a note buried in an entry. As an event, on its own line, with the old medication and dose and the new one. Everything after it reads differently, and in six months you will need to know exactly where the boundary was.
Start a new dose series. Do not continue the numbers. A chart that runs 1.0 mg of semaglutide into 5 mg of tirzepatide implies a fivefold increase that did not happen.
Reset your expectations about side effects. The first weeks on a new medication are not comparable to the last weeks on the old one, and levels of the new one climb for several weeks before they plateau. Judging the switch on its first fortnight is judging it early.
Keep weight and side effect severity continuous across the boundary — those scales still mean the same thing, and the comparison across the switch is exactly what you will want later.
What to log either way
- Medication name, every time
- Dose, with its unit
- Injection date and site
- Side effects with severity and the day of the cycle
- Weight as a trend
- Every dose change, and what your provider said about it
Get those right and the log stays readable across a switch, a dose change, or a gap in treatment. The side effect guide covers the severity fields, and the titration guide covers laying the schedule out as dates.
One practical warning if you are choosing a tracker: not all of them let you change medication without starting over, and some will happily plot two incompatible dose scales on one axis. If a switch is a live possibility, test that before you commit history to an app. The tracker comparison covers what else is worth checking.
Ozempic®, Wegovy®, Mounjaro® and Zepbound® are trademarks of their respective owners. Gleva is not affiliated with, endorsed by or sponsored by them.