What 'safest' really means with weight loss injections
Both Mounjaro and Wegovy are prescription-only medicines — meaning a qualified prescriber has already decided that the medicine is appropriate for the individual receiving it. Neither is available without a prescription, and suitability is assessed on a person-by-person basis by a healthcare professional.
How they work
Wegovy contains semaglutide, a GLP-1 receptor agonist that acts on appetite-regulating pathways to reduce hunger and increase feelings of fullness. Mounjaro contains tirzepatide, a dual GIP and GLP-1 receptor agonist that works on two of these pathways. Both are given as once-weekly injections using pre-filled pens.
Commonly reported side effects
The side-effect profiles of both medicines overlap considerably. Gastrointestinal effects — nausea, constipation, diarrhoea, indigestion — are among the most commonly reported with both. Injection-site reactions, fatigue, and headache are also reported. These effects are often most noticeable after a dose change and tend to ease over time for many people, though experiences vary.
Both medicines carry additional monitoring requirements and are subject to post-marketing surveillance. If you experience a side effect, it is worth reporting it to your national reporting scheme (such as the UK's Yellow Card scheme) and discussing it with your healthcare professional.
The role of your prescriber
Questions about which injection is safer or more suitable for you personally are ones only your prescriber or doctor can answer with your full health history in front of them. No general comparison can substitute for that clinical conversation. If you are already prescribed one of these medicines and have concerns, your prescriber is the right first call.
For a broader look at how these medicines compare factually, see our pages on comparing weight loss injection options and which weight loss injection may suit your journey — both written for people already on a prescribed treatment.
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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Tracking your injection safely with GLP Trackr
One practical way to stay on top of your safety throughout treatment is to keep a clear, consistent record of your injections and how you feel after each one. That is where GLP Trackr is built to help.
Injection-site rotation
Rotating your injection site — between the abdomen, thigh, and upper arm — is a standard part of using pre-filled injection pens, and it matters for skin health over time. GLP Trackr logs each site you use and suggests your next rotation automatically, so you never have to keep a mental note or guess where you last injected.
Side-effect logging
If you notice nausea, fatigue, or any other symptom after a dose, logging it in the app creates a timestamped record you can bring to your next prescriber appointment. Over time, the side-effect tracker can reveal patterns — for example, whether symptoms cluster around injection day or ease as the week progresses — giving you and your prescriber something concrete to discuss.
You can also explore what people on weight loss injections commonly track to get more from their treatment. For a full overview of how these medicines are used, visit our weight loss injections hub.
GLP Trackr does not replace your prescriber's guidance — it helps you arrive at each appointment better informed. If any symptom feels severe, persistent, or worrying, contact your healthcare professional promptly rather than waiting for your next scheduled review.
Want a clear picture of every injection, every site, and every symptom in one place? Download GLP Trackr on the App Store or Google Play and try it free for 7 days — no commitment needed.
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.
You're Not on This Journey Alone.
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 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.
Both Mounjaro and Wegovy are prescription-only medicines assessed by a prescriber before being recommended. Neither can be ranked as universally safest — suitability and safety depend on your individual medical history, which only your prescriber or doctor can properly evaluate.
Nausea, constipation, diarrhoea, indigestion, fatigue, and injection-site reactions are among the most commonly reported effects with both Mounjaro and Wegovy. These often ease over time for many people, but experiences vary. Discuss any concerns with your healthcare professional.
Results vary between individuals and are influenced by many factors including diet, activity, and how the body responds to the medicine. No general claim about speed or effectiveness applies to everyone. Your prescriber is best placed to discuss what you might realistically expect.
Rotating injection sites — between abdomen, thigh, and upper arm — is standard practice with pre-filled injection pens. GLP Trackr logs each site you use and suggests your next rotation automatically, helping you maintain a consistent rotation without having to remember manually.
Contact your prescriber or doctor promptly if you experience severe, persistent, or worrying symptoms after an injection. Do not wait for a scheduled review if something feels wrong. The GLP Trackr side-effect log can help you document what happened and when.