Tirzepatide: The Injection Behind the Letter T
Tirzepatide is the active substance in Mounjaro, a prescription-only, once-weekly injectable medicine. It belongs to a class of medicines known as dual GIP and GLP-1 receptor agonists — meaning it acts on two hormone pathways involved in appetite and blood sugar regulation. Many people experience a reduced sense of hunger and increased feelings of fullness, effects that are commonly attributed to these pathways.
How it is taken
Tirzepatide is supplied as a pre-filled pen and is injected once a week, on the same day each week if possible. The three most commonly used injection sites are the abdomen, the front of the thigh, and the outer upper arm. Rotating between these sites at each injection is generally recommended, as injecting repeatedly into the same spot can cause skin changes over time.
Dose titration
Treatment typically starts at a low dose and is adjusted over time — always by your prescriber, based on how you are responding. The dose strengths commonly associated with tirzepatide are 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. Any decision about which dose you are on, or when to move to the next stage, belongs with your prescriber or doctor — not something to decide independently.
Tirzepatide carries a black triangle (▼) designation in some countries, meaning it is subject to additional monitoring. Any side effects worth noting should be reported to your healthcare professional and, where applicable, to your national reporting scheme (such as the UK's Yellow Card scheme).
For a broader look at injectable weight management medicines, see our guide to weight loss injections. You may also find it useful to read about how weight loss injections generally work, or to explore our page on comparing injectable options.
average weekly weight change in the first 16 weeks of Mounjaro & Wegovy use*
Tracking the right four numbers — weight, waist, protein and dose — turns a noisy chart into a clear story. That's the loop GLP-1 users keep coming back for.
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Keeping Your Tirzepatide Injections on Track with GLP Trackr
Staying consistent with a once-weekly injection schedule is straightforward in theory, but easy to lose track of in practice — especially when you are also rotating sites, monitoring how you feel, and adjusting to a new routine. GLP Trackr is built specifically to take that friction away.
Injection-site rotation, simplified
The site-tracking feature lets you log where each injection was given — abdomen, thigh, or upper arm — and the app keeps a rotation history so it can suggest your next site automatically. No more trying to remember which side you used last week.
Dose logging and reminders
Every injection can be logged with its date, time, and dose strength, giving you a clear record of your full treatment history. Dose reminders mean your weekly schedule stays on track even during a busy week — because missing a dose is something best discussed with your prescriber, not something to navigate by guessing.
If you ever do miss a dose, log it in the app and bring that record to your next conversation with your prescriber or doctor — they are best placed to advise on what to do next. Any decision about your injection schedule should always be made with your prescriber, never on your own.
Ready to take the guesswork out of injection-site rotation? Download GLP Trackr free on the App Store or Google Play — your first 7 days are on us. You can also explore our page on accessing weight loss injections for more context on this treatment area.
What does glptrackr include?
10+ powerful features. One app. Built specifically for Mounjaro and Wegovy users.
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Morning Check-In
Start every day with a 60-second wellness check-in. Log how you're feeling, track nausea, appetite, energy, and mood — giving you and your care team a complete picture of how your medication is working.
Injection Tracking
Log every dose with a single tap. Track your dose history, phase in your cycle, estimated medication levels, and upcoming injection dates — with reminders so you never miss a scheduled shot.
Hydration Reminders
Staying hydrated is especially important on GLP-1 medications. Set daily water targets, log intake throughout the day, and receive smart nudges when you're falling behind your goal.
Smart Meal Planning
Personalized meal plans built around your current dose phase and side effects. Every meal is GLP-1 optimized — high in protein, gentle on the stomach, and scaled to your reduced appetite.
Recipe Library
Browse 50+ high-protein, GLP-1-friendly recipes filtered by meal type, prep time, and dietary needs. Every recipe includes full nutrition info, step-by-step instructions, and tips for eating with side effects.
Progress Analytics
Beautiful, easy-to-read charts show your weight loss trajectory, weekly nutrition trends, medication responses, and wellbeing scores over time — turning raw data into genuine insights.
AI Meal Scanning
Snap a photo of any meal and get a full nutrition breakdown in seconds — calories, protein, carbs, fat, and fibre. No searching. No manual logging. Just point, snap, and track.
Exercise & Steps
Log walks, workouts, and movement with activity targets that flex with your energy levels. On lower-energy dose days, gentler targets keep you moving without burning out.
Community Support
Connect with thousands of others navigating the same medication journey. Share milestones, ask questions, find accountability partners, and get support from people who truly understand.
Never Forget a Dose Again.
Log your Mounjaro or Wegovy injection in seconds. Track your pen, your dose level, and your injection site — so you always know exactly where you are in your treatment.
Watch Your Body Transform, Week by Week.
Log your weight, measurements, and how you're feeling after each dose. GLPTrackr turns your data into clear, motivating charts that show you how far you've really come.
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The Most Advanced GLP-1 Brain Ever Built.
The first AI built exclusively for GLP-1 weight loss. Every insight, every meal plan, every prediction trained on one thing only: helping you get the most out of your medication.
Knows Your Cycle
GLPIQ tracks where you are in your injection cycle and adjusts everything around it: lighter meals on nausea days, higher protein when appetite returns, and smarter targets as your medication level shifts.
Predicts Before You Feel It
GLPIQ learns your personal side effect patterns over time. After a few cycles, it starts warning you the morning before a rough day — and adjusts your meal plan automatically.
Finds Your Golden Dose
GLPIQ analyses every dose you've been on: weight loss rate, side effects, food noise, mood, protein adherence and tells you which dose gave you the best results. No other app does this.
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Frequently asked questions.
The weight loss injection starting with T is tirzepatide, the active substance in Mounjaro. It is a prescription-only, once-weekly injectable medicine that acts on GLP-1 and GIP receptors to help regulate appetite. It must be prescribed by a qualified healthcare professional.
Tirzepatide is commonly injected into the abdomen, front of the thigh, or outer upper arm. Rotating between sites at each injection is generally recommended to avoid skin changes. Your prescriber or the patient information leaflet for your specific pen will provide personalised guidance.
Yes, rotating injection sites is generally recommended when using tirzepatide. Repeatedly injecting the same spot can cause localised skin changes. Logging each site in an app like GLP Trackr can help you track your rotation history and know where to inject next.
Any decision about a missed dose should be made with your prescriber or doctor — not independently. Log the missed injection in GLP Trackr so you have an accurate record to share at your next appointment. Your healthcare professional can advise on the right next step.
GLP Trackr lets you log each injection with its date, time, dose, and site. It tracks your rotation history and suggests your next injection site automatically, and sends dose reminders so your weekly schedule stays consistent. It is a tracking tool, not a medical service.