Wegovy: uses, dosage and side effects

What Wegovy is used for

Wegovy is licensed for weight management in adults living with obesity, and in adults with overweight who also have a weight-related health problem such as high blood pressure, type 2 diabetes, obstructive sleep apnoea or joint disease, always together with a reduced-calorie diet and more physical activity. Semaglutide imitates the gut hormone GLP-1: it slows stomach emptying and acts on appetite regulation in the brain, so people feel full sooner and think about food less. It is the same active substance as in Ozempic, which is licensed for type 2 diabetes, but the two are different products with different dosing and they should not be substituted for each other. Wegovy is not a cosmetic quick fix. Weight regain after stopping is well documented, so the licence and the clinical evidence both point towards continuing treatment with periodic review rather than a short course.

Side effects of Wegovy

The effects reported most often are gastrointestinal: nausea, vomiting, diarrhoea, constipation, abdominal pain, indigestion, burping and reduced appetite. They are strongest in the early weeks and after each dose increase and usually ease with time; smaller meals, less fatty food and adequate fluid help. Headache, dizziness, tiredness, hair thinning and injection site reactions are also described. Gallstones are a common effect and rapid weight loss makes them more likely: in the trials they were reported in about 1.6 in 100 people treated, with gallbladder inflammation in about 0.6 in 100. Inflammation of the pancreas is less common, about 0.2 in 100 people treated, but serious. Low blood sugar is uncommon on its own but is much more likely if semaglutide is combined with insulin or a sulfonylurea. Stop the injection and seek urgent medical help immediately if you have severe, persistent abdominal pain spreading to the back, if you cannot keep fluids down, or if your face or throat swells and breathing becomes difficult. In an emergency in Ireland ring 112 or 999.

The eyes carry a warning of their own. A sudden loss of vision in one eye, usually painless, needs a prompt eye examination and must be reported to the prescriber. Epidemiological studies show an increased risk of a blood-supply problem in the optic nerve during semaglutide treatment, and the medicine is stopped if that is confirmed. This applies whether or not you have diabetic retinopathy.

Dosage and how to take it

Wegovy is injected under the skin of the abdomen, thigh or upper arm once a week, on the same day each week, with or without food. Treatment starts at a low dose and is increased in planned steps over several months up to the maintenance strength, which is how the licence is written and which is what keeps nausea manageable; each step is a prescribing decision, not a self-adjustment. Rotate injection sites. If a dose is missed, the leaflet explains when it can still be given and when to skip it and resume on your usual day, and your pharmacist can talk you through it. Pens are stored in the fridge before first use, with separate limits once a pen is in use. Progress is reviewed periodically, and prescribers usually reassess whether continuing is worthwhile if weight has not changed meaningfully after a defined period at the maintenance dose.

Is Wegovy available without a prescription in Ireland?

No. Wegovy is a prescription-only medicine in Ireland, authorised centrally through the European Medicines Agency, and no pharmacy may supply it over the counter. Demand for GLP-1 medicines has produced a large grey market, and falsified semaglutide pens have been identified in Europe; regulators including the HPRA have warned about products bought outside the legal supply chain, and injecting an unverified liquid is a genuine hazard rather than a theoretical one. Sellers that ship without a prescription are, by definition, outside that chain. Compounded semaglutide from a website is not an authorised medicine in the European Union. A prescription written by a doctor in another EU or EEA country can be dispensed in Ireland when it carries the details required for cross-border prescriptions, and the Pharmaceutical Society of Ireland publishes guidance for pharmacists on how to handle those. We do not sell medicines and we do not send them to Ireland.

Continuing treatment and repeat prescriptions

If a prescriber has already started you on Wegovy and you want to continue the same treatment, you can ask for a prescription through our weight management questionnaire. There is no video consultation, no telephone appointment and no live chat: you complete a structured medical questionnaire and a doctor assesses it separately. The assessment is carried out by lek. Damian Wojno, a doctor registered in Poland, PWZ no. 3211301. If he agrees that treatment can continue, you receive a cross-border prescription as a PDF by e-mail, with the fields set out in the Annex to Directive 2012/52/EU, and you bring the printout to any pharmacy in Ireland with your ID document. There is no PIN code and nothing to look up in an Irish system. We never supply the medicine itself, and we do not state how long an assessment takes. The fee covers the medical consultation, not the issuing of a document - the doctor decides after reviewing your form. If the doctor declines for medical or legal reasons, we refund the fee in full. If the doctor asks you for documentation, you have at least 7 days to provide it, and we will remind you before the deadline; if the consultation cannot be completed, we also refund the full amount.

Cost and reimbursement in Ireland

Weight management with a GLP-1 medicine is largely a private cost in Ireland. Reimbursement decisions are made separately for each product and indication, and the HSE publishes what is currently covered, so check there rather than relying on any figure quoted online, including on this page. Pharmacies set their own private prices for the pens, which is why quoted monthly costs vary widely between pharmacies and over time as the dose is increased. The Drugs Payment Scheme applies to prescribed medicines dispensed in a community pharmacy and caps what one household pays in a calendar month; whether a particular product is covered by a scheme in your circumstances is a question for your pharmacist. Budget for the medicine itself rather than only for a consultation, and treat any offer that seems far below the pharmacy price as a warning sign about where the product came from.

Interactions and alcohol

Semaglutide slows stomach emptying, so it can change the speed at which other medicines taken by mouth are absorbed. That matters most for medicines with a narrow margin between an effective and an excessive level, and for anyone taking insulin or a sulfonylurea, where the combination clearly increases the risk of low blood sugar and those doses are usually reviewed. Rapid weight loss can also change the dose needed for blood pressure medicines and for thyroid replacement, so those are monitored as weight falls. Tell your pharmacist and prescriber about everything you take, including over-the-counter medicines and supplements. Alcohol is not formally prohibited, but it adds calories, disinhibits eating, irritates the stomach and worsens nausea, and it can destabilise blood glucose in people who also take diabetes medicines. If you drink, keep it modest and avoid drinking on an empty stomach.

Who should not take Wegovy

Wegovy must not be used by anyone who has had a hypersensitivity reaction to semaglutide or to any ingredient of the pen. It is not licensed as a treatment for type 1 diabetes and is not a substitute for insulin. Caution and closer supervision apply if you have had pancreatitis or gallstones, severe gut disease including gastroparesis or inflammatory bowel disease, significantly reduced kidney function, or diabetic retinopathy that is being treated, since rapid improvement in blood sugar can temporarily worsen it. Anyone with a history of an eating disorder should be assessed carefully before an appetite-suppressing medicine is used. Before any procedure under general anaesthesia or deep sedation, and before an endoscopy, tell the team that you use a GLP-1 medicine. Slower stomach emptying can leave food in the stomach despite the fasting you were told to follow, and that food can enter the lungs as anaesthesia is started. Wegovy is not intended for people who simply want to lose a few kilograms and do not meet the criteria in the licence.

Generic and brand names

The active substance is semaglutide, and Wegovy is the brand licensed for weight management, supplied as a pre-filled pen at several strengths up to the 2.4 mg maintenance dose. The same molecule is marketed as Ozempic for type 2 diabetes and as Rybelsus in an oral form; these are separate products with separate licences and dosing, and using one in place of another is a prescribing decision rather than a swap. There is no generic semaglutide in the European Union: the molecule is under patent, so anything advertised as generic or compounded semaglutide is not an authorised medicine, whatever the website says. On a cross-border prescription the medicine should be named by its international non-proprietary name, semaglutide, together with the brand, the strength, the form and the quantity, so that an Irish pharmacist can dispense the correct pen without ambiguity.

Pregnancy and breastfeeding

Wegovy should not be used during pregnancy. Weight loss is not appropriate in pregnancy and human data are limited, so the product information advises stopping the medicine when a pregnancy is planned or discovered, and because of the long half-life it sets that interval at at least two months before a planned pregnancy. Effective contraception is advised during treatment. It is not known whether semaglutide passes into human breast milk, so it is not recommended while breastfeeding. If you become pregnant unexpectedly while using it, contact your GP or prescriber for advice rather than simply continuing. Fertility can improve as weight falls, which surprises some people, so contraception deserves an explicit conversation at the start of treatment rather than an assumption. Our online questionnaire does not lead to prescriptions for use during pregnancy or breastfeeding.

Patient information leaflet

Every pack sold in Ireland contains a patient information leaflet, and the same leaflet is published online. The Health Products Regulatory Authority (HPRA) is the medicines regulator here and lists authorised products with their leaflets and summaries of product characteristics; medicines.ie publishes the same documents for products marketed in Ireland. For Wegovy the European Medicines Agency also publishes the full product information, because the medicine was authorised centrally for the whole European Union, and the instructions for using the pen are part of that leaflet rather than an optional extra. Read them before your first injection and again after each change of strength. If anything does not match what you were told, ask your pharmacist rather than guessing; pharmacists in Ireland are registered with the Pharmaceutical Society of Ireland. A suspected side effect can be reported by you directly to the HPRA.

Who wrote and checked this page

This page was prepared by the medical content team at MEDINOW Sp. z o.o. and reviewed by lek. Damian Wojno, a doctor registered in Poland, PWZ no. 3211301. He holds no Irish registration and does not practise in Ireland; he works to Polish professional rules and issues cross-border prescriptions under Directive 2011/24/EU and Directive 2012/52/EU, which is the framework an Irish pharmacist applies when a prescription comes from another EU or EEA country. The content was verified on 29 August 2026 against the sources listed below, all of them official or regulator-published. This page is general information about a medicine: it is not personal medical advice, not a diagnosis and not an offer of the medicine itself, which we never supply. If your symptoms are new, severe or changing, contact your GP or a pharmacist; in an emergency in Ireland ring 112 or 999.