Weight-loss injections, especially GLP-1 analogues used weekly, have entered the public discourse in Europe and Spain. We're talking about drugs like semaglutide or liraglutide, known commercially as Ozempic/Wegovy or Saxenda, and even tirzepatide (Mounjaro), which have generated high expectations due to their ability to aid weight loss.
Along with this surge in popularity comes increasing scrutiny of its safety, proper indications, and necessary clinical follow-up. The balance shifts between proven heart benefits from large trials and warnings about potential mental health effects and contraindications during periods such as postpartum and breastfeeding.
What are they and how do they work?
These medications mimic the action of an intestinal hormone involved in appetite and glucose regulation. In clinical practice, they are administered subcutaneously at regular intervals and, under medical supervision, can decrease appetite and food intake , as well as contribute to metabolic improvements. Their use requires a prescription and an individual assessment of risks and benefits.
Mental health under scrutiny: signs and monitoring
In the UK, a patient was reported who, after starting semaglutide, developed intense anxiety, loss of enjoyment, and crying spells that forced discontinuation of treatment, according to their doctor. In the US, product information lists depression and suicidal ideation among the possible adverse events, while patient information in the UK did not always highlight them as clearly.
Although regulators in the US and Europe have concluded that the overall balance of these therapies is favorable, the UK's Medicines and Healthcare products Regulatory Agency (MHRA) actively reviews safety data and encourages reporting any suspected adverse reactions through the adverse event reporting system. If symptoms consistent with a mental health problem appear, the recommendation is to stop taking the medication and consult a healthcare professional immediately .
Pregnancy, breastfeeding and postpartum: when not to use them
Breastfeeding support organizations warn that, currently, GLP-1 agonists are not recommended during breastfeeding due to a lack of conclusive evidence regarding their passage into breast milk and effects on the infant. In fact, there has been a notable increase in consultations from mothers regarding weight loss and the use of these medications postpartum.
Hormonal health specialists point out that the postpartum period is a vulnerable time, marked by significant physical and emotional changes, and warn about the lack of adequate supervision when prescriptions are obtained online without a thorough evaluation. Furthermore, accelerated weight loss can impact milk production and the mother's well-being, increasing the risk of complications.
A practical aspect is added: rapid weight loss can disrupt cycles and fertility signals, so extra caution is advised when using contraception if pregnancy is not desired. The experts' position is clear: during pregnancy, breastfeeding, or when trying to conceive, these medications should be avoided except in cases of very strong clinical justification and with close monitoring.
Clinical evidence: beyond body weight
The SELECT trial, published in The Lancet, evaluated semaglutide in overweight or obese individuals with cardiovascular disease but without diabetes. With 17.604 participants assigned to either weekly injections or placebo, an approximate 20% reduction in major cardiovascular events (heart attack, stroke, or cardiovascular death) was observed in the treatment group.
Subsequent analyses led by University College London suggest that the reduction in abdominal circumference explains approximately one-third of the cardioprotective effect, while the benefit remains regardless of initial weight. Cardiologists in Spain emphasize that these data support a possible direct protective effect beyond weight loss, likely mediated by multiple mechanisms (inflammation, endothelial function, blood pressure, or lipids).
Endocrinologists consulted emphasize that this type of evidence supports its use in patients with obesity and cardiovascular risk, and even raises questions about future indications in other populations. However, they note that, for now, the trials have been conducted in people with a BMI above 27 , so extending its use to other groups requires further studies and regulatory approval.
Access and monitoring in Spain: what to keep in mind
In our setting, access is contingent upon prescription and monitoring by specialists, who assess medical history, concomitant treatments, and adverse effects. Furthermore, it is crucial to monitor clinical response, waist circumference, metabolic control, and tolerance, adjusting the dose or discontinuing treatment if necessary.
These injections are not a shortcut without commitment: they can cause nausea or other discomfort, and if discontinued without consolidating lifestyle changes, there is a risk of rebound weight gain and muscle loss . A balanced diet, physical activity, and behavioral support remain essential for maintaining results over time.
Real-life cases: expectations, costs, and limitations
A patient in Spain treated with liraglutide (Saxenda) reported a significant reduction in appetite and a weight loss of 27 kilos ; after which her weight plateaued. The cumulative cost was high, around €3.000 in one year, illustrating the financial impact and the need for realistic treatment planning with professional support.
Another case, that of a businessman who used semaglutide to reverse weight gain, describes moderate weight loss with improved well-being and a greater sense of control, but acknowledges that without consistent habits, the weight can return. His current approach involves seeing his doctor for prescriptions and checkups when needed, and reinforcing healthy habits to avoid relying on continuous reset cycles.
A trend that changes behaviors
In Latin America, a consumer study found that 11% of households already use or are considering using injectable weight-loss medications. Among those who use or plan to use them, changes in their food basket are observed (fewer sugary drinks and fatty foods). Even so, the authors warn of mixed signals regarding prevention and checkups, emphasizing that the medication does not replace basic healthcare.
The debate surrounding weight-loss injections is settling on a common idea: harnessing their therapeutic potential when appropriate, while remaining mindful of safety precautions . Among emerging cardiovascular benefits, mental health concerns, and restrictions during pregnancy or breastfeeding, the key point is responsible, informed use, always under medical supervision.