Weight Loss Injections: Common Questions, Honest Answers

Mounjaro and Wegovy are both once-weekly injectable medicines supplied as pre-filled pens. Mounjaro contains tirzepatide, a dual GIP and GLP-1 receptor agonist; Wegovy contains semaglutide, a GLP-1 receptor agonist. Both act on appetite-regulating pathways — many people experience a reduced sense of hunger and increased feelings of fullness, alongside slower stomach emptying, particularly in the early weeks.

Prescriptions and medical supervision

These medicines are prescription-only in most countries worldwide. Obtaining them requires assessment and authorisation by a qualified prescriber or doctor. There is no legitimate route to access them without a prescription — anyone suggesting otherwise is offering something outside a regulated clinical pathway, which carries real risks. If you have questions about your prescription or access to your medicine, speak with your prescriber or doctor directly.

Side effects: what is commonly reported

Side effects are real and worth tracking. The most commonly reported include nausea, vomiting, diarrhoea, constipation, indigestion, fatigue, and injection-site reactions. These do not affect everyone, and for many people gastrointestinal effects ease over time — but they vary considerably from person to person. No medicine is free of side effects, and anyone claiming otherwise is not giving you the full picture.

If you have had your gallbladder removed or have an existing health condition, it is especially important to discuss this with your prescriber before starting or continuing treatment, as individual medical history affects suitability.

Dose consistency and injection sites

Weekly injections are typically given into the abdomen, front of the thigh, or upper arm. Rotating between sites with each injection is important — using the same spot repeatedly can cause skin changes that affect how the medicine is absorbed. Your prescriber or the patient information leaflet that came with your pen is the best guide to technique.

For a broader overview of how these medicines are used, see our guide to weight loss injections. If cost or pricing is something on your mind, our pages on injection pricing factors and finding value in your treatment may also be useful — though we never list or quote prices ourselves.

Staying consistent with a weekly injection — and rotating sites correctly — is easier when you have a reliable record. GLP Trackr's injection-site tracking and rotation feature lets you log each injection with the site used (abdomen, thigh, or arm), and the app keeps a history so it can suggest where to inject next. Over weeks, that adds up to a clear, automatic rotation record you don't have to hold in your head.

Alongside site tracking, dose logging captures the date, time, and dose strength of every injection in one place — useful when your prescriber asks how your treatment has been going, or when you want to check back on your own schedule. Dose reminders help make sure a weekly shot doesn't get forgotten in a busy week.

If you experience side effects and want to keep track of how they change over time, the side-effect log lets you record symptoms and spot patterns — information that can be genuinely useful to bring to your next prescriber appointment.

GLP Trackr is available free on the App Store and Google Play. Start a 7-day free trial and see how much simpler it is to stay on top of your injection routine.

GLP Trackr is a tracking app, not a medical service. It does not replace the advice of your prescriber or doctor. If you experience severe, persistent, or worrying symptoms, contact your healthcare professional promptly. Any questions about your dose, your prescription, or whether this medicine is right for you belong with your prescriber — they know your full history.