Taula de Continguts
- What GLP-1 medicines are and how they work
- Ozempic, Wegovy and Mounjaro: what each one is and what it is authorised for
- Who it may be indicated for and who it is not for
- Side effects: what the official package leaflets say
- Contraindications and precautions before starting
- What happens when treatment stops and why the whole plan matters
- How we work at Santé Madrid
- Frequently asked questions
GLP-1 treatment for weight management means a prescription medicine, such as semaglutide or tirzepatide, used together with changes to diet and physical activity, and only after a medical assessment and only if it is indicated. In Madrid, as in the rest of Spain, not everyone who wants to lose weight meets the authorised conditions of use. We explain what Ozempic, Wegovy and Mounjaro are, who they are authorised for, which side effects and precautions their official information lists and how we work at Santé Madrid.
Key points
- Ozempic and Wegovy contain semaglutide; Mounjaro contains tirzepatide. They are prescription medicines and are not chosen by brand name, but according to the medical assessment.
- According to the European Medicines Agency, Ozempic is authorised for type 2 diabetes, while Wegovy and Mounjaro also have an authorised indication for weight management in adults who meet specific criteria.
- The most common side effects are digestive: nausea, vomiting, diarrhoea, constipation and abdominal pain. There are less common but important effects, such as pancreatitis.
- They are not used during pregnancy and require caution in several medical situations. That is why the prior medical consultation is not a formality.
- In studies, weight tends to return when treatment stops. Results vary from person to person and no figures can be promised.
What GLP-1 medicines are and how they work
GLP-1 is a hormone that the gut produces naturally after eating. Medicines in this group mimic its action. According to the European Medicines Agency (EMA), semaglutide is a GLP-1 receptor agonist that helps regulate appetite, increases the feeling of fullness and reduces food intake, hunger and cravings (EMA, Wegovy public overview).
Tirzepatide works in a similar way, but acts on two receptors: the GLP-1 receptor and the GIP receptor, GIP being another gut hormone. The EMA explains that targeting these receptors reduces appetite and helps people manage their weight, as well as increasing insulin release in response to food in people with type 2 diabetes (EMA, Mounjaro public overview).
They are injectable medicines that can only be obtained with a prescription. They are not a supplement or a cosmetic product: they have authorised indications, known side effects and situations in which they are not recommended. The regimen is decided by the prescribing physician according to the summary of product characteristics and is not part of this article.
Ozempic, Wegovy and Mounjaro: what each one is and what it is authorised for
The three names often appear together, but they are not interchangeable. The table summarises the EMA's public information on each medicine. It is not a comparison of effectiveness or a recommendation: the choice, where appropriate, is made by the physician after the assessment.
| Medicine | Active substance | How it works | Authorised indication in the EU |
|---|---|---|---|
| Ozempic | Semaglutide | GLP-1 receptor agonist | Adults with type 2 diabetes that is not satisfactorily controlled, together with diet and exercise |
| Wegovy | Semaglutide | GLP-1 receptor agonist | Weight management together with diet and physical activity in adults with obesity, or with overweight and a weight-related health problem |
| Mounjaro | Tirzepatide | GLP-1 and GIP receptor agonist | Type 2 diabetes, and weight management together with diet and physical activity in adults with obesity, or with overweight and a weight-related health problem |
According to the EMA, Ozempic is a medicine for type 2 diabetes (EMA, Ozempic public overview). The Spanish Agency of Medicines and Medical Devices (AEMPS) has asked physicians to prioritise GLP-1 analogues according to their authorised conditions, especially for blood glucose control in patients with type 2 diabetes, because of supply problems, and has warned of cases of off-label prescribing and of dispensing without a prescription (AEMPS, supply situation of GLP-1 analogues). It is one more reason for the decision always to be a medical one.
Who it may be indicated for and who it is not for
The EMA describes precisely who the weight management indication is for. In adults, Wegovy and Mounjaro are used together with diet and physical activity in people with a body mass index (BMI) of 30 kg/m² or more, or with a BMI of at least 27 kg/m² and less than 30 kg/m² when there are weight-related health problems, such as high blood pressure, abnormal blood fat levels, obstructive sleep apnoea or diabetes (EMA, Wegovy; EMA, Mounjaro).
This means these medicines are not designed for losing a few kilos before the summer or an event. Nor do they replace diet, rest and movement: the indication presents them as support for those changes.
BMI is only a starting point. In a medical assessment of this kind, personal and family history, regular medication, previous digestive problems, a possible wish to become pregnant and each person's relationship with food are usually reviewed as well. With all of that, the physician decides whether a medicine from this group makes sense or whether another approach is better. Meeting the BMI criteria does not mean the treatment is suitable, and not meeting them does not mean nothing can be done: sometimes the way forward is nutrition, exercise or a referral to another specialist.
Side effects: what the official package leaflets say
Like any medicine, semaglutide and tirzepatide can cause side effects, although not everybody gets them. The package leaflets published by the AEMPS in its online medicines information centre (CIMA) list them in detail; here we summarise the most relevant ones (Wegovy package leaflet on CIMA; Mounjaro package leaflet on CIMA).
- Digestive. Nausea, vomiting, diarrhoea, constipation and abdominal pain are among the very common effects. The leaflets state that they are usually more frequent at the start of treatment and tend to decrease over time.
- Dehydration. Vomiting and diarrhoea can cause fluid loss, which in turn can affect kidney function. That is why drinking enough fluids is stressed.
- Acute pancreatitis. It is uncommon. Severe, persistent stomach pain, which may spread to the back, requires seeing a physician immediately.
- Gallbladder. The leaflets list gallstones and, in the case of tirzepatide, inflammation of the gallbladder.
- Others. Dizziness, tiredness, injection site reactions, changes in taste or hair loss, among others.
There are also effects that depend on the active substance. In 2025, the EMA's safety committee concluded that non-arteritic anterior ischaemic optic neuropathy (NAION), an eye condition that may cause loss of vision, is a very rare side effect of semaglutide, and advised contacting a physician without delay in case of sudden loss of vision or rapidly worsening eyesight (EMA, PRAC on semaglutide and NAION).
Contraindications and precautions before starting
The formal contraindication listed in the leaflets is allergy to the active substance or to any of the other ingredients. But there are quite a few more situations in which use is not recommended or calls for caution, and it is worth knowing them before the consultation.
If you have diabetes, your care for the condition remains in the hands of your GP or your endocrinologist. In the consultation we will ask you to tell us about all your medication and, if there are doubts, to discuss it with them. If any symptom worries you, speak to the physician and do not adjust anything on your own.
What happens when treatment stops and why the whole plan matters
A common question is whether the weight stays off when the medicine is stopped. The available data call for caution. The EMA describes a study in which, after an initial period on semaglutide, the people who switched to placebo regained weight, and concludes that treatment needs to continue in order not to regain it (EMA, Wegovy).
Along the same lines, the extension of the STEP 1 trial followed a subgroup of participants for one year after semaglutide and the lifestyle intervention were stopped. On average, participants regained a large part of the weight they had lost, and many of the cardiometabolic improvements moved back towards baseline values. The authors interpret this as showing that obesity is a chronic disease and that ongoing treatment appears necessary to maintain the improvements (Wilding et al., 2022). It was an exploratory analysis with a limited number of people, but it points in the same direction.
That is why, when a treatment of this kind is indicated, it is worth approaching it from the outset as a medium and long-term plan: diet, physical activity, sleep, medical follow-up and a clear idea of what will happen when it is reduced or stopped. Results vary from person to person.
How we work at Santé Madrid
Santé Clinics Madrid is at C. de Amador de los Ríos, 1, Chamberí, 28010 Madrid. We are open Monday to Friday from 9:00 to 21:00 and on Saturdays from 10:00 to 15:00; the clinic is closed on Sundays.
At our Madrid clinic, weight management with GLP-1 medicines is only considered after a medical consultation, which costs €50. In it, the Santé Madrid medical team reviews your medical history, your medication and your goals, calmly explains the possible side effects and precautions, and decides whether the treatment is indicated in your case. If it is not, we will tell you and guide you towards other options. You can read more about the service on our GLP-1 treatment page.
Nutrition is part of the plan, not an add-on. That is why we also offer a nutrition consultation, which costs €50, to work on habits you can keep up over time. If you want to know which questions are covered in a first visit, our guide to the weight management consultation explains it in more detail.
We make no promises about kilos or timeframes: when treatment is indicated, it is prescribed and supervised by the medical team, and results vary from person to person.
Frequently asked questions
Can I start GLP-1 treatment without a medical consultation?
No. These are prescription medicines, used only after a medical assessment and only if indicated. The consultation is for checking whether you meet the conditions of use, reviewing your medication and explaining the risks before deciding.
Are Ozempic and Wegovy the same medicine?
They contain the same active substance, semaglutide, but have different authorised indications. According to the EMA, Ozempic is authorised for type 2 diabetes and Wegovy for weight management in adults who meet specific criteria.
What is the difference between semaglutide and tirzepatide?
Semaglutide acts on the GLP-1 receptor. Tirzepatide acts on the GLP-1 and GIP receptors. Both reduce appetite; which one is suitable, if any, is decided by the physician according to your case.
How much weight is lost with these medicines?
It is not possible to promise a figure. The response varies a great deal between people and also depends on diet, physical activity and follow-up. Results vary from person to person.
What are the most common side effects?
The most frequent are digestive: nausea, vomiting, diarrhoea, constipation and abdominal pain. There are also less common and more serious effects, such as pancreatitis or gallstones, which are explained in the consultation.
What happens if I stop treatment?
Studies show that weight tends to return when it is stopped. That is why the plan includes diet, physical activity and medical follow-up, and any change to treatment is decided with the physician.
Can I use it if I am pregnant or want to become pregnant?
It must not be used during pregnancy, and if you are trying to conceive the physician will tell you how far in advance to stop it, according to the summary of product characteristics. Always mention it in the consultation so your case can be assessed.
How much does the medical consultation cost at Santé Madrid?
The medical consultation costs €50, and the nutrition consultation also costs €50. In the medical consultation we assess whether the treatment is indicated before proposing anything.
If you are considering GLP-1 treatment in Madrid, the first step is a calm medical conversation about your health, your medication and your goals. At Santé Madrid we will explain which options make sense in your case, including when the answer is that this treatment is not for you.
