What the evidence says about the safety of weight loss injections
Mounjaro and Wegovy are both prescription-only medicines, meaning they can only be prescribed after a healthcare professional has assessed whether they are appropriate for you. This gatekeeping exists precisely because individual suitability matters.
Commonly reported side effects
The most frequently reported side effects are gastrointestinal: nausea, vomiting, diarrhoea, constipation, indigestion, and reflux. These are most common when starting treatment or after a dose increase, and many people find they ease as the body adjusts over time. Other commonly reported effects include fatigue, headache, dizziness, and reactions at the injection site such as mild redness or discomfort.
Less common but important considerations
Some individuals report more significant effects, including changes in mood, gallbladder-related symptoms, or in rare cases pancreatitis-like symptoms. Anyone experiencing severe or persistent abdominal pain, significant vomiting, or any symptom that feels serious should contact a healthcare professional promptly rather than waiting. These medicines are also not recommended during pregnancy, and anyone who is pregnant, breastfeeding, or trying to conceive should discuss this with their prescriber before continuing treatment.
Ongoing monitoring
Both medicines currently carry additional monitoring requirements in some countries — for example, in the UK they hold a Black Triangle (▼) status, meaning healthcare professionals and patients are encouraged to report suspected side effects through their national reporting scheme (such as the UK's Yellow Card scheme). If you experience a side effect you are unsure about, your prescriber or pharmacist can advise whether it should be reported and how.
For a broader look at what these medicines are and how they work, see our guide to what weight loss injections are. For a more detailed safety-focused overview, you may also find our pages on the safety of weight loss injections and the safety of slimming injections helpful. Full prescribing information is available via the electronic Medicines Compendium (eMC), which publishes the official patient information leaflets for both medicines.
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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How GLP Trackr helps you stay on top of your safety and wellbeing
One of the most practical things you can do while taking a weight loss injection is keep a clear record of how you feel over time — and that is exactly where GLP Trackr is built to help.
Side-effect and symptom tracking
GLP Trackr's side-effect tracking feature lets you log symptoms as they occur — nausea, fatigue, injection-site reactions, digestive changes — and view them as a pattern across your journey. Rather than trying to recall how you felt three weeks ago when you speak to your prescriber, you have a clear, timestamped record to refer to. This kind of documentation can make those appointments far more productive and help your prescriber make well-informed decisions about your care.
Injection-site logging and rotation
The app also tracks your injection sites — abdomen, thigh, upper arm — and suggests your next rotation automatically. Consistently rotating sites is generally recommended to reduce localised reactions, and having the app manage that history for you removes one thing to remember each week.
For a comprehensive guide to everything covered on this topic, visit our weight loss injections hub.
Always follow the guidance of your prescriber or doctor — they know your full medical history and are best placed to advise on whether these medicines are right for you and how to manage any effects you experience. GLP Trackr is a tracking companion, not a substitute for that professional relationship.
If you want a clearer picture of your own journey — side effects included — GLP Trackr is free to try for 7 days on the App Store and Google Play. Download it free and see what a complete log of your progress looks like.
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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Connect with thousands of real GLP-1 users sharing their wins, side effect tips, and meal ideas. Get the support of people who truly get it — because they're living it too.
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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.
Both are prescription-only medicines with well-studied safety profiles. They are prescribed only when a healthcare professional judges them appropriate for the individual. Side effects are common, particularly gastrointestinal ones, but many ease over time. Your prescriber is the right person to assess safety for your specific situation.
The most commonly reported side effects are nausea, vomiting, diarrhoea, constipation, indigestion, and fatigue. These tend to be most noticeable after starting treatment or following a dose increase, and many people find they become less pronounced as their body adjusts.
If you experience severe or persistent abdominal pain, significant vomiting, symptoms that feel serious or unusual, or any side effect that worries you, contact your healthcare professional promptly. Do not wait to see if it resolves on its own when something feels wrong.
These medicines are generally not recommended during pregnancy or breastfeeding. Anyone who is pregnant, trying to conceive, or breastfeeding should discuss this with their prescriber or doctor before continuing or starting treatment. This is a decision that requires individual clinical assessment.
Logging symptoms as they happen — rather than trying to recall them later — gives you and your prescriber a clearer picture. GLP Trackr's side-effect tracking feature lets you record symptoms over time so you can spot patterns and bring an accurate record to your next prescriber appointment.