How Weight Loss Injections Work and Where They Are Given
Both Mounjaro and Wegovy are prescription-only, once-weekly injectable medicines. Mounjaro contains tirzepatide, a dual GIP and GLP-1 receptor agonist, while Wegovy contains semaglutide, a GLP-1 receptor agonist. According to guidance from the electronic Medicines Compendium, both are supplied as pre-filled injection pens designed for subcutaneous use — meaning the injection goes into the layer of fat just beneath the skin.
Common Injection Sites
The three sites most commonly used for these injections are:
- Abdomen — the area around the stomach, avoiding the navel
- Upper thigh — the front or outer part of the thigh
- Upper arm — the outer area of the upper arm
Your prescriber or doctor will advise on which sites are suitable for you and how to use them safely. The information leaflet that comes with your pen is the definitive guide to technique — always refer to that, and ask your healthcare professional if anything is unclear.
Why Injection-Site Rotation Matters
Rotating the site of each weekly injection is widely recommended to reduce the chance of skin reactions, such as lumps or irritation at a single spot. Many people find it helpful to keep a simple record of which site they used each week so they are not returning to the same area repeatedly. You can read more about managing your weight loss injection routine and explore general guidance on weight loss injections as a whole.
Access and Prescribing
In the UK, these medicines are prescription-only and are obtained through a prescriber and a registered pharmacy. How they are accessed — whether through a public health scheme, a private prescriber, or an online clinic — varies by individual circumstances. If you have questions about your prescription or eligibility, your prescriber or doctor is the right person to ask. For context on how weight loss injections are supplied and what to consider, see our overview of weight loss jab availability.
average weekly weight change in the first 16 weeks of Mounjaro & Wegovy use*
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Tracking Your Injection Routine with GLP Trackr
Staying on top of a weekly injection schedule is straightforward in theory but easy to lose track of in practice — especially when you are also rotating sites and monitoring how you feel after each dose.
GLP Trackr's injection-site tracking feature is built specifically for this. Each time you administer your injection, you log the site you used — abdomen, thigh, or arm — and the app keeps a running rotation history so it can suggest where to inject next. Over time, you build a clear record of every shot: date, dose strength, and site, all in one place.
The app also sends dose reminders so your weekly schedule stays on track even on a busy week. And if you ever want to bring a summary of your injection history to a prescriber appointment, that data is already there, organised and ready.
If you experience any side effects around your injection site — redness, swelling, or discomfort — the app's side-effect log lets you note these alongside each injection entry, which can be useful to discuss with your healthcare professional. Always follow the guidance of your prescriber or doctor; if a reaction is severe, persistent, or worrying, contact them promptly rather than waiting for your next appointment. You can also explore what to consider before obtaining a weight loss injection if you have questions about the process.
GLP Trackr is free to try for 7 days — download it on the App Store or Google Play and start logging your injection routine today.
What does glptrackr include?
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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 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.
Weight loss injections like Mounjaro and Wegovy are typically given subcutaneously — into the fat just beneath the skin — at the abdomen, upper thigh, or upper arm. Your prescriber or doctor will advise on the right sites for you, and your pen's leaflet provides full technique guidance.
Yes, rotating injection sites is widely recommended to reduce the risk of skin reactions such as lumps or irritation. Keeping a record of which site you used each week helps you avoid returning to the same spot too soon. GLP Trackr can log this automatically and suggest your next site.
In the UK, weight loss injections such as Mounjaro and Wegovy are prescription-only medicines obtained through a prescriber and a registered pharmacy. How you access them — via a public scheme, private prescriber, or online clinic — depends on your individual circumstances. Your prescriber or doctor can advise.
Mild redness or tenderness at an injection site is commonly reported and often temporary. If a reaction is severe, persistent, or concerns you, contact your healthcare professional promptly. You can log injection-site reactions in GLP Trackr to build a record to discuss at your next appointment.
Yes. GLP Trackr includes dose reminders to keep your once-weekly injection schedule on track, alongside a log of each injection's date, dose, and site. This makes it straightforward to stay consistent and to review your history with your prescriber or doctor.