Tirzepatide Tracker — Mounjaro, Zepbound and Compounded Doses

You searched for "tirzepatide" rather than a brand name, and that usually means one of three things. You are comparing Mounjaro and Zepbound, you have heard it works differently from semaglutide, or the vial in your fridge came from a compounding pharmacy and has no brand on it at all. This page is for all three.

What makes tirzepatide different from other GLP-1 medicines?

Most medicines in this family, like semaglutide, act on one hormone receptor: GLP-1. Tirzepatide acts on two. Its labels describe it as a GIP receptor and GLP-1 receptor agonist — GIP being glucose-dependent insulinotropic polypeptide, another gut hormone involved in blood sugar and appetite.

The Zepbound label puts it carefully: GLP-1 is a known regulator of appetite, and studies in animals suggest GIP may add to that effect. Both receptors are found in brain areas involved in appetite. What that means in daily life varies from person to person, which is why your own record tends to be more useful than any general explanation.

Mounjaro or Zepbound — what actually differs?

Same molecule, same maker, different approvals.

	Mounjaro	Zepbound
Approved for	Type 2 diabetes (adults and children 10+)	Weight management; moderate to severe obstructive sleep apnea with obesity (adults)
Starting dose	2.5 mg weekly for 4 weeks	2.5 mg weekly for 4 weeks
Steps	2.5 mg, at least 4 weeks apart	2.5 mg, at least 4 weeks apart
Maximum	15 mg (10 mg for children)	15 mg
Forms	Single-dose pen or vial, multi-dose vial, KwikPen	Single-dose pen or vial, multi-dose vial, KwikPen

Both labels share the same missed-dose rule — take it within 4 days (96 hours), otherwise skip it — and the same 3-day minimum gap if you move your shot day. The label's half-life for tirzepatide is about 5 days, which is part of why it is a once-weekly medicine.

What about compounded tirzepatide?

Compounded tirzepatide is made by a pharmacy rather than by Lilly, and it is not the same as an FDA-approved product. The FDA is direct about this: compounded drugs are not FDA approved, and the agency does not review them for safety, effectiveness or quality before they are sold.

During the national shortage, the FDA allowed some compounding of tirzepatide. On December 19, 2024 it decided the shortage was resolved, and its compounding page sets out that the grace period for state-licensed pharmacies has ended and that outsourcing facilities had until March 19, 2025.

The FDA has also received reports of dosing errors with compounded GLP-1 injections — people drawing up the wrong amount, and in some cases miscalculations by health care professionals. As of May 31, 2026, the FDA listed more than 730 adverse event reports for compounded tirzepatide, and notes that this likely undercounts what has happened, because many pharmacies are not required to report.

What should I write down if my vial is compounded?

More than you would for a branded pen. Compounded products can differ in strength from one pharmacy — or one refill — to the next. A clear record makes it much easier for your prescriber or pharmacist to spot a mismatch.

What we'd track

Whichever tirzepatide you use, these are the things we would log.

1. Each weekly dose in milligrams, and the product name. Mounjaro, Zepbound or the compounding pharmacy — it changes which label applies.
2. For vials, the concentration and the volume you drew. Write it exactly as your pharmacy label and pharmacist instructed; Holt records what you log and never chooses a dose.
3. The injection site. Both labels ask you to rotate with every dose.
4. Side effects by day. Stomach symptoms often cluster after a dose step; a timeline shows whether they settle.
5. Meals, protein and water. Appetite can drop sharply, and dehydration is one of the label's concerns.

Holt keeps all of this on your iPhone, reminds you on shot day with a Live Activity and turns it into a report for your appointment. It is free to download, with an optional subscription.

Keep a clear tirzepatide log with Holt