Which drugs interact with Wegovy, and what should you tell your prescriber?

Why gastric emptying changes what other medicines do

The evidence base for semaglutide's interaction profile starts with its pharmacology. By activating GLP-1 receptors in the gut wall and brainstem, semaglutide substantially reduces the rate at which food (and anything dissolved in the stomach) moves into the small intestine. For most drugs, absorption is fastest in the small intestine, so slowing transit can delay their peak plasma concentration. Whether that delay matters clinically depends on the medicine involved.

For drugs with a wide therapeutic window taken at a consistent time each day, a modest delay is usually inconsequential. For time-sensitive medicines (certain antibiotics taken before food, some analgesics, or drugs with a steep concentration-effect curve) it can matter more. The BNF entry for semaglutide lists the interaction categories recognised by UK prescribers. Checking it before starting Wegovy is standard practice for any clinician reviewing a patient on multiple medicines.

In practical terms, the most commonly affected categories are oral diabetes medicines, hormonal contraceptives and anticoagulants. None of those interactions is an automatic bar to treatment, but each needs a plan agreed with your prescriber before you start your first pen.

Diabetes medicines: the interaction that most often needs action

A question our prescribers hear most weeks is whether it is safe to continue insulin or a sulphonylurea (such as gliclazide) while starting Wegovy. The short answer is: yes, but the doses of those existing medicines usually need revisiting. Wegovy lowers blood glucose independently of insulin pathways, so adding it to an existing regimen that already includes insulin or a sulphonylurea creates a meaningful risk of hypoglycaemia, blood sugar falling further than intended.

NICE's appraisal of semaglutide, TA875, expects that patients already on insulin will have their insulin dose adjusted when starting Wegovy. Your prescriber should review your HbA1c, your current doses and your self-monitoring pattern before issuing the first prescription. If your diabetes is managed by metformin alone, the interaction risk is far lower, metformin does not cause hypoglycaemia on its own and does not appear to have a clinically significant interaction with semaglutide.

Other glucose-lowering drug classes (DPP-4 inhibitors, SGLT-2 inhibitors) carry a lower hypoglycaemia risk in combination, but your prescriber will still want the full picture declared.

Oral contraceptives, HRT and other absorption-sensitive medicines

The oral contraceptive question is one where Wegovy and Mounjaro differ slightly. For tirzepatide (Mounjaro), UK guidance is explicit: add a non-oral contraceptive method for the first four weeks of treatment and for four weeks after each dose increase. For semaglutide, the evidence of reduced pill effectiveness is less certain, but the NHS advises discussing this with your prescriber or GP because absorption can still be affected during titration. If you are exploring every category of Wegovy drug interaction, the contraceptive question is among the most practically important ones to raise.

Warfarin and other anticoagulants warrant particular care. Semaglutide may affect how consistently warfarin is absorbed, which shifts INR readings unpredictably. If you take warfarin, your INR should be monitored more frequently when Wegovy is introduced or when the dose is increased. Direct oral anticoagulants (DOACs) such as apixaban or rivaroxaban have a different absorption profile and a lower interaction signal, but they should still be declared.

Levothyroxine, taken by many people for an underactive thyroid, is another time-sensitive oral medicine. It is typically taken first thing in the morning on an empty stomach, and gastric-emptying delay can theoretically affect its absorption consistency. Keep the timing steady and tell your endocrinologist or GP that you have started Wegovy so they can recheck thyroid function at the next routine review.

For broader context on how these interactions compare to those seen with other GLP-1 medicines, the semaglutide interaction overview covers the wider picture. And if you want to compare how Wegovy's profile differs from Mounjaro's, the Wegovy overview sets that out clearly.

Medicines that interact less than people expect, and the ones worth double-checking

Not every drug combination is a concern. SSRIs, common blood pressure medicines (ACE inhibitors, calcium channel blockers, thiazides), statins and most antihistamines do not have established clinically significant interactions with semaglutide. The slowed gastric emptying tends not to affect medicines that are absorbed proximally or that have such a wide therapeutic window that a timing shift is irrelevant.

That said, two categories are worth a specific mention. First, alcohol: it does not interact with Wegovy pharmacologically, but nausea is already the most common side effect during titration, and alcohol reliably worsens it. Second, over-the-counter NSAIDs (ibuprofen, naproxen): semaglutide can increase the risk of nausea and gastrointestinal discomfort, and NSAIDs add further GI irritation. There is no absolute prohibition, but regular heavy NSAID use alongside Wegovy is worth flagging.

If you are already on Wegovy through another provider and want to move your prescription, a clinical consultation at nume includes a full medicines review before any prescription is issued. The detailed Wegovy drug interaction guide goes further on specific drug classes if you want to read ahead, and our dedicated page covering interactions with Wegovy is a useful reference if you want to check a specific medicine before your consultation. Cost context for private treatment is covered on the Wegovy price page, if that is useful background before you book.