Wegovy Contraindications: When Semaglutide Is Not the Right Choice

The biggest misconception: 'Wegovy is just not suitable for people with thyroid problems'

When people hear about thyroid contraindications for Wegovy, they often assume it applies broadly to anyone with any thyroid condition, an underactive thyroid, Hashimoto's disease, or a thyroid nodule picked up on an ultrasound. That is not accurate. The specific contraindication is for a rare cancer called medullary thyroid carcinoma (MTC), or a family history of it. The concern comes from animal studies in which semaglutide caused thyroid C-cell tumours; whether this translates to humans is not yet established, but the risk is taken seriously enough to make MTC and its associated syndrome, Multiple Endocrine Neoplasia type 2 (MEN2), hard stops. A well-managed underactive thyroid, by contrast, is not automatically a barrier. This distinction matters enormously in practice. People with common thyroid conditions frequently avoid asking about semaglutide because they assume they will be turned away, and many of them would, after proper assessment, be considered suitable candidates. A detailed consultation with a prescriber who knows your thyroid history is the only way to find out where you stand. Collapsing all thyroid conditions into a single contraindication is a misconception that stops people from having a conversation worth having. If you would like to read more about the full picture of who the medicine is licensed for, the licensed indications for semaglutide page covers the eligibility criteria in more depth.

Absolute contraindications to semaglutide: the non-negotiables

Some contraindications to Wegovy sit outside clinical judgement. They are absolute, and a responsible prescriber will not proceed regardless of how strong the case for treatment might otherwise appear. The first is any personal history of medullary thyroid carcinoma, or a first-degree family member who has had it. The second is a diagnosis of MEN2, a rare genetic syndrome that raises thyroid and other gland cancer risk significantly. The third is confirmed hypersensitivity to semaglutide or to any ingredient in the Wegovy pen. Allergic reactions to GLP-1 medicines can range from localised injection-site swelling to rare but serious anaphylactic responses; anyone who has previously reacted to semaglutide should not receive it again.

Pregnancy is also a firm contraindication. Semaglutide is not recommended during pregnancy, while breastfeeding, or for people actively trying to conceive. The MHRA advises using effective contraception throughout treatment and for a period after stopping before attempting to conceive, your prescriber will advise on the specific washout period. For tirzepatide users, there is an additional consideration: oral contraceptive pill absorption may be reduced in the first weeks of treatment and after each dose increase, so an extra barrier method is recommended during those windows. The equivalent evidence does not currently exist for semaglutide, but the broader contraception guidance still applies. Wegovy is also not licensed for anyone under 18.

Relative contraindications: where the clinical picture really matters

Beyond the absolute rules, there are several conditions that make semaglutide use more complicated rather than impossible. A history of pancreatitis sits in this category. In January 2026, the MHRA issued a Drug Safety Update specifically highlighting acute pancreatitis as a known, infrequent but potentially serious risk with GLP-1 receptor agonists. Anyone with a prior episode of pancreatitis should discuss this frankly with a prescriber; in many cases it will preclude treatment, though the decision depends on the underlying cause and clinical history.

Severe gastrointestinal disease (including gastroparesis, inflammatory bowel disease, or significant gastric emptying problems) requires careful assessment. Because semaglutide slows gastric emptying as part of how it works, adding it in someone whose gut already moves slowly can worsen symptoms meaningfully. Severe renal impairment and severe hepatic impairment are further areas where the prescribing information urges caution; neither is automatically a contraindication at every stage, but both require prescriber review of current function and other medicines. Diabetic retinopathy is worth flagging too: rapid improvements in blood glucose can occasionally worsen retinopathy in the short term, so anyone with this condition needs it taken into account during assessment. For a full picture of how Wegovy sits alongside other treatments, if you want to understand how semaglutide interacts with other medications you may already be taking, that page covers the combinations that need closest attention, and you can also find out which medications cannot be taken with semaglutide before your consultation, with further detail available on the Wegovy medication interactions page if you want to look at specific combinations in more depth.

What happens at the consultation, and why it is not just a box-ticking exercise

A consultation for a prescription medicine like Wegovy is a genuine clinical review. At nume, a GPhC-registered Independent Prescriber reads every submission personally, there is no automated decision engine involved. They look at your weight history, current medical conditions, any medications you take, family history, and what you are hoping to achieve. The thyroid and pancreas history will be asked about directly. So will your contraceptive situation if you are of reproductive age.

This is also the stage at which relative contraindications get properly weighed. Someone with well-controlled hypertension and a history of mild reflux is a very different clinical picture from someone with active inflammatory bowel disease, both deserve individual assessment rather than a blanket rule. If Wegovy is not the right fit, the prescriber can discuss whether other aspects of the Wegovy programme might still be relevant or whether a different licensed treatment could be explored instead. The weight loss treatment overview at nume covers the full range of options available through private prescription. Pricing and what is included in the service can be found on the Wegovy cost page, which lays out what a private prescription actually covers. Whatever the outcome, you will have a clear answer, the same day, from a clinician, not a waiting list.

If you have questions about a specific condition before starting a consultation, the frequently asked questions section covers the most common ones, and the support team is available seven days a week. When you are ready to have your full medical history reviewed, start your free consultation and a prescriber will assess whether semaglutide is appropriate for you.