How to Track Your GLP-1 Injections: Sites & Schedule

Tracking your GLP-1 injections means keeping a simple record of three things: the date you injected, the site you used, and the dose. That record helps you rotate sites to protect your skin, stay on a consistent weekly schedule, and avoid the two most common slip-ups, double-dosing and missed weeks. None of this changes what or how much you inject; it is about organizing what your prescriber already set up.

This guide covers how to log injections, why site rotation matters, how to think about your weekly schedule, and what tracking does for the bigger picture of your results. For anything dose-related, your prescriber and the instructions that came with your pen are the authority.

Why tracking your injections is worth the effort

A once-weekly injection sounds easy to remember until a busy week blurs into the next and you genuinely cannot recall whether Tuesday's shot happened. A written or in-app log removes the guesswork. It is a small habit that prevents a few specific problems.

First, it protects against accidental double-dosing, which is a real risk when you are not sure if you already injected. Second, it flags missed weeks early, so you can follow your medication's missed-dose guidance and talk to your prescriber rather than discovering a gap later. Third, a clean log of dates and sites makes your appointments faster, because you can show your clinician exactly what happened instead of reconstructing it from memory.

There is a fourth benefit that most people overlook. Once you are logging the dose itself, you have the backbone for connecting it to everything else: your side effects, your appetite across the week, and your body-composition trends. A dose log is the timeline that the rest of your data hangs on.

Where GLP-1 injections go: the three main sites

Most once-weekly GLP-1 medications, including Ozempic/Wegovy (semaglutide) and Mounjaro/Zepbound (tirzepatide), are designed for subcutaneous injection, meaning into the fat layer just under the skin rather than into muscle or a vein. The three sites the manufacturers generally describe are the abdomen, the front of the thigh, and the back of the upper arm.

To be clear about scope: the table below is general education on how these sites compare for tracking and rotation purposes. It is not a recommendation to switch sites or inject in a way other than what your prescriber and your pen's instructions specify. Absorption notes are broad and individual results vary.

Site	Absorption notes	Rotation tips	Convenience
Abdomen	Commonly described as a consistent, reliable site for subcutaneous absorption; manufacturers often instruct staying a couple of inches away from the navel.	Plenty of surface area to move around the area week to week; easy to vary left and right.	High: easy to see, easy to reach, comfortable while seated.
Thigh	The front of the thigh is a standard subcutaneous site; absorption can vary with activity in that limb.	Alternate left and right thighs; vary the spot within each.	Medium: easy to reach and see, though some prefer not to inject before leg-heavy activity.
Upper arm	The back of the upper arm is a standard site; often easier to reach with help than alone.	Alternate arms; the surface area is smaller, so vary the exact spot carefully.	Lower for self-injection: the angle can be awkward without assistance.

The practical takeaway is not which site is "best." It is that you have options, and rotating among them is generally recommended to keep any single patch of skin from taking every shot. Always follow the specific guidance from your prescriber and the instructions for your pen.

What site rotation actually prevents

Reusing the exact same point repeatedly can lead to skin irritation, bruising, and lipohypertrophy, the medical term for the firm lumps of thickened tissue that can form at overused injection sites. Those lumps are not just cosmetic; injecting into them can affect how the medication is absorbed. The general principle clinicians describe is to spread injections out so no single spot is overworked.

Logging the site each week is what makes rotation real instead of aspirational. If your log shows you have hit the right side of your abdomen three weeks running, that is your cue to move. Without a record, "I think I used the other side last time" is just a hopeful guess.

Building a consistent weekly schedule

Once-weekly GLP-1 medications are designed around a steady rhythm. Semaglutide has a half-life of roughly 7 days and tirzepatide roughly 5 days, according to pharmacokinetic data, which is why a consistent weekly cadence helps keep drug levels relatively stable rather than swinging (PNAS 2024; product pharmacokinetic data). Half-life is the time it takes for the amount of drug in your body to fall by half.

Picking a fixed day and a rough time of day is the simplest way to stay consistent. Many people anchor it to something they already do every week so it is hard to forget. The specific day is yours to set with your prescriber, and if you ever need to shift it, that is their call to guide, not a solo experiment. If you want to understand why the day matters for how you feel across the week, our explainer on the GLP-1 dose week and PK curve walks through how levels rise and fall between shots.

A reminder system closes the loop. Whether it is a phone alarm or a tracking app's notification, the goal is to make the injection happen on schedule without relying on willpower or memory.

Handling a missed dose

Missed doses happen, and the right response depends entirely on your specific medication and how much time has passed. Manufacturer instructions for semaglutide and tirzepatide products differ, and they also depend on how close you are to your next scheduled dose, so there is no one-size answer here and this article will not give you one.

The responsible sequence is: check the official instructions that came with your medication, and contact your prescriber or pharmacist if anything is unclear. Then log the miss. Marking a missed dose in your tracker does two things: it keeps you from accidentally double-dosing because you "feel behind," and it gives your clinician an honest picture of your adherence pattern at your next visit.

What to log for every injection

The minimum useful log is small. For each shot, capture:

• The date (and the day of week, so your cadence is visible at a glance).
• The site you used (abdomen, thigh, or arm, plus left or right).
• The dose, exactly as your prescriber set it.
• Anything notable: a skipped week, a site that looked irritated, or a new lump to mention to your clinician.

That is genuinely it for the core log. Everything else is optional context. If you also jot down how your appetite and side effects tracked across the days that followed, you start to see your personal pattern, which is the entire premise of tracking GLP-1 side effects systematically.

If you are using a compounded product drawn from a multi-dose vial, your log has a few extra fields to keep straight, like the vial's concentration and your dose in units. That is its own logistics problem, covered in our guide to tracking compounded semaglutide and tirzepatide.

From a dose log to the full picture

A standalone injection log is useful. A log that sits next to the rest of your data is more useful. The reason is correlation: the day you injected is the anchor that lets you make sense of how you felt, how your appetite moved, and whether your body composition is trending the way you want.

This is the gap many dose-only apps leave. They log the shot and stop there. Myo handles the dose side too, with date, site, and schedule logging plus an injection-site body map that shows your last-used spot and hints when to rotate, and a missed-dose marker, all free for one medication. The difference is that Myo keeps that injection log next to your weight, side effects, protein, and body-composition data, so the whole picture lives in one place instead of scattered across a notes app and a separate scale. If you are weighing your options, our roundup of the best GLP-1 tracking apps compared lays out how the main trackers stack up.

The injection itself is the one fixed point in your week. Logging it well is the cheapest, highest-leverage tracking habit you have, and it is the foundation everything else builds on, including the muscle-preservation work covered across the rest of the GLP-1 and muscle loss guide.

References

• PNAS (2024). Pharmacokinetics of semaglutide and related GLP-1 receptor agonists. doi:10.1073/pnas.2415815121.
• Product pharmacokinetic data for once-weekly semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound), summarized in trimrx and pharmacy pharmacokinetic references.
• Manufacturer instructions for use for each respective GLP-1 product (the authority for injection technique, sites, schedule, and missed-dose handling).