Mounjaro

Mounjaro is the brand name for tirzepatide — a once-weekly injectable, prescription-only medicine made by Eli Lilly and licensed in the UK for weight management and type 2 diabetes. It is given as a pen injection and the dose is increased in steps.

Source: Mounjaro Summary of Product Characteristics (emc)

Tirzepatide

Tirzepatide is the active ingredient in Mounjaro. It is a dual GIP and GLP-1 receptor agonist, meaning it mimics two natural gut hormones to reduce appetite and slow how quickly the stomach empties, so you feel full for longer.

Source: Mounjaro SmPC · BNF

Wegovy

Wegovy is the brand name for semaglutide 2.4 mg — a once-weekly injectable, prescription-only medicine made by Novo Nordisk and licensed in the UK for weight management. Like Mounjaro, it is a pen injection with a stepped dose.

Source: Wegovy SmPC (emc)

Semaglutide

Semaglutide is the active ingredient in Wegovy and Ozempic. It is a GLP-1 receptor agonist that reduces appetite and food intake. The same molecule is licensed under different brand names for weight management (Wegovy) and type 2 diabetes (Ozempic).

Source: Wegovy / Ozempic SmPC · BNF

Ozempic

Ozempic is a brand of semaglutide licensed in the UK for type 2 diabetes — not for weight loss. It contains the same active ingredient as Wegovy but has a different licence and different doses. Using a diabetes medicine off-licence for weight loss is not how we supply treatment.

Source: Ozempic SmPC (emc)

GLP-1 (glucagon-like peptide-1)

GLP-1 is a natural hormone released by your gut after eating. It signals fullness to the brain and helps regulate blood sugar. Weight-loss injections work by mimicking this hormone.

Source: NHS · BNF

GLP-1 receptor agonist

A GLP-1 receptor agonist is a class of medicine that activates the GLP-1 receptor to reduce appetite and food intake. Semaglutide is a GLP-1 receptor agonist; tirzepatide acts on the GLP-1 receptor and the GIP receptor.

Source: BNF

GIP (glucose-dependent insulinotropic polypeptide)

GIP is a second gut hormone involved in appetite and blood-sugar control. Tirzepatide (Mounjaro) acts on both the GIP and GLP-1 receptors — the dual action that distinguishes it from semaglutide, which acts on GLP-1 alone.

Source: Mounjaro SmPC

Orlistat

Orlistat is an oral weight-loss medicine that reduces how much dietary fat your gut absorbs. It is available as a prescription-only medicine (Xenical) and, at a lower strength, as a pharmacy medicine (Alli). It is a tablet, not an injection.

Source: BNF

BMI (body mass index)

BMI is a weight-for-height measure (kg/m²) used to assess eligibility for weight-loss treatment. Treatment is generally considered at a BMI of 30 or more, or 27 or more when you also have a weight-related health condition. Your pharmacist confirms eligibility.

Source: NICE

Titration (dose escalation)

Titration means gradually increasing a medicine's dose over weeks so your body can tolerate it. Mounjaro starts at 2.5 mg once weekly and rises in steps (5, 7.5, 10, 12.5 mg) to a maximum of 15 mg, with at least four weeks between increases.

Source: Mounjaro SmPC

Prescription-only medicine (POM)

A prescription-only medicine can only be supplied after a prescriber or pharmacist confirms it is clinically appropriate for you. UK weight-loss injections are POMs, so they always require a consultation and clinical check — never an over-the-counter purchase.

Source: Human Medicines Regulations 2012

Subcutaneous injection

A subcutaneous injection is given into the fat layer just under the skin — usually the abdomen, thigh or upper arm. This is how weight-loss pens are administered, once a week, using a short fine needle.

Source: Product SmPC

Emergency contraception (morning-after pill)

Emergency contraception is medicine taken after unprotected sex to help prevent pregnancy. It is more effective the sooner it is taken, so it is best not to wait. It is available from a pharmacist, discreetly and confidentially.

Source: NHS · FSRH