GLP-1 Tracker App: What to Log Each Week and What Labels Say

What is a GLP-1 tracker, and which medicines does it cover?

A GLP-1 tracker is an app that keeps a dated record of a weekly GLP-1 medicine and the habits around it. It stores each dose, the injection site, the day of the next shot, body weight, protein, water and notes you want to show a clinician. The medicines it covers are semaglutide, sold by Novo Nordisk as Ozempic and Wegovy, and tirzepatide, sold by Eli Lilly as Mounjaro and Zepbound. Their labels describe once-weekly injections.^[1][2][3][4] Retatrutide, a once-weekly Eli Lilly drug, is still in clinical trials and has no approved label, so a tracker can only record what a person enters for it.^[9] A tracker is not a prescriber. It records what you enter, never chooses a dose, and does not replace the instructions that come with your pen or vial. PepTrac works with both pens and vials, and it is educational record-keeping software, not medical advice.

What should you track on a GLP-1 medicine each week?

Track the few records that answer the questions a clinician asks at a visit. Start with the dose, the date and the time, because every other number is read against them. Add the injection site, since the Ozempic, Mounjaro and Zepbound labels all name the abdomen, thigh and upper arm.^[1][3][4] Add body weight, because the pivotal trials measured weight over 68 to 72 weeks, so a trend over months says more than one weigh-in.^[5][6] Add protein and water, which are the daily habits most people ask about, and note your supply: how many doses are left in a pen or vial and when it was opened. PepTrac keeps these in one log and counts down to the next dose. It has no dedicated side-effect log, so keep symptoms in another app or your own notes.

Dose and time

The amount you entered, the date and the clock time of each shot.

Injection site

Where the shot went. The labels name the abdomen, thigh and upper arm.^[1][3]

Weight

A weekly or daily weigh-in, read as a trend over months.

Protein and water

Daily totals from the food log, with water logged separately.

Supply

Doses left in a pen or vial, and the date a vial was mixed or opened.

How often are GLP-1 shots taken, and how do doses step up?

Ozempic, Wegovy, Mounjaro and Zepbound are each injected once a week, and each label raises the dose in steps. The Ozempic label starts at 0.25 mg weekly for 4 weeks, then moves to 0.5 mg.^[1] The Wegovy label lists 0.25, 0.5, 1 and 1.7 mg in four-week steps, then a maintenance dose of either 1.7 mg or 2.4 mg, with 2.4 mg recommended.^[2] The Mounjaro label starts at 2.5 mg and adds 2.5 mg after at least 4 weeks on the current dose, up to 15 mg.^[3] The Zepbound label starts at 2.5 mg for 4 weeks, with maintenance doses of 5, 10 or 15 mg.^[4] These are label facts, not advice: your prescriber sets your dose and your pace. In PepTrac you enter the schedule you were given as steps of dose plus duration, and the last step holds until you change it.

What happens if you miss a GLP-1 dose?

Each label gives its own window, and the windows differ. The Ozempic label says to give a missed dose as soon as possible within 5 days after it was due.^[1] The Mounjaro and Zepbound labels set the window at 4 days, which is 96 hours.^[3][4] The Wegovy label keys the rule to the next scheduled dose: if it is more than 2 days away, give the missed dose as soon as possible, and if it is less than 2 days away, do not give it.^[2] Outside those windows the labels send you back to your regular schedule, and your prescriber or pharmacist can answer what to do in your case. A tracker cannot decide this for you. What it can do is show exactly how many days have passed since the last logged dose, so you are comparing your own count with the label text instead of guessing from memory.

Can an app show your GLP-1 level, and how accurate is it?

An app can estimate a level, but it cannot measure one. Semaglutide has an elimination half-life of about 1 week and reaches steady state after 4 to 5 weeks of weekly dosing.^[1] Tirzepatide has a half-life of about 5 days and reaches steady state after 4 weeks.^[3] PepTrac feeds those half-lives and each drug's time to peak into a one-compartment model and draws the result as a curve with a shaded band, plus a dotted projection from your schedule. The band comes from re-running the model with the half-life and peak time each changed by 20 percent, so it shows sensitivity, not a statistical confidence interval. The numbers are in relative units scaled to each dose, not nanograms per millilitre. They are estimates, not lab results, and one drug's scale cannot be compared with another's.

Where do GLP-1 injections go, and how do you track the site?

The Ozempic and Wegovy labels say to inject under the skin of the abdomen, thigh or upper arm.^[1][2] The Mounjaro and Zepbound labels name the same three areas and say another person should inject the back of the upper arm.^[3][4] Which area and which side you use is a choice to make with your clinician. What a tracker adds is memory: after months of weekly shots, few people can say where the last four went. PepTrac records the site with each dose on a body map and shows your last site and your site history. It shows where you have been, so you can see a pattern at a glance, but it does not recommend the next site, because that choice belongs to you and your clinician. For a closer look at technique and site choice, see the peptide injection sites guide.

Why track protein, water and weight alongside the shot?

Because the shot is one input and the daily routine is the rest of the picture. In the STEP 1 trial of semaglutide 2.4 mg, adults lost a mean 14.9 percent of body weight over 68 weeks against 2.4 percent on placebo, and nausea and diarrhea were the most common adverse events.^[5] In SURMOUNT-1, the mean change at 72 weeks was 15.0, 19.5 and 20.9 percent on tirzepatide 5, 10 and 15 mg against 3.1 percent on placebo.^[6] Results unfold over many months, so a weight trend, protein totals and water logged beside each dose give you something concrete to bring to an appointment. PepTrac logs food with an AI meal scan from a photo or a barcode, tracks water, and reads steps and calories burned from Apple Health. The GLP-1 protein calculator gives a reference range in grams.

How do you track compounded GLP-1 vials in syringe units?

Compounded vials add arithmetic that pens hide. You divide the milligrams in the vial by the millilitres of water to get a concentration, divide your dose by that concentration to get a volume, and then read that volume as units on the syringe. A 5 mg vial mixed with 2 mL is 2.5 mg per mL, so 0.25 mg is 0.1 mL, which is 10 units on a U-100 syringe. That example is arithmetic, not a suggested dose. The FDA says it has received reports of dosing mistakes with compounded semaglutide and counted 990 adverse event reports for it as of May 31, 2026. It also says to discard a multiple-dose vial within 28 days after first use, even if medication remains.^[7] PepTrac does the unit conversion for the values you enter, so check every result against your label.

• Semaglutide: semaglutide dose calculator and semaglutide tracker
• Tirzepatide: tirzepatide dose calculator and tirzepatide tracker
• Vial math in general: peptide reconstitution calculator

Which GLP-1 tracker app should you choose?

We recommend PepTrac. It is the tracker this page describes: it logs each dose, draws your estimated level as a range, converts vial doses into U-100 or U-40 syringe units, and keeps peptides, food and workouts in the same iPhone app. A level range matters because the label half-lives are about 1 week for semaglutide and about 5 days for tirzepatide, so every shot lands on top of the last.^[1][3] We make PepTrac, so we publish our reasoning. The best GLP-1 tracker apps page ranks six apps on seven stated criteria from their public listings, and the Shotsy alternative page compares two apps row by row. Both say that PepTrac publishes them, and every competitor cell links to its listing. PepTrac is an iPhone app; the comparison lists each app's platforms. Features and prices change, so check a listing before you decide.