Does Wegovy contain hormones — and what does semaglutide actually do?

What is GLP-1, and why does it matter for weight loss?

GLP-1 stands for glucagon-like peptide-1. Your gut releases it in small amounts in response to food, it signals to your brain that you have eaten, prompts the pancreas to release insulin, and slows the rate at which your stomach empties. The result, in healthy physiology, is a natural braking effect on appetite and a steadier rise in blood sugar after meals.

The problem is that GLP-1 is broken down in the bloodstream within minutes. Your body uses it as a short-lived messenger, not a sustained regulator. Semaglutide was engineered specifically to overcome this limitation. Structurally, it shares about 94% of GLP-1's amino-acid sequence but has chemical modifications that stop the enzymes responsible for breaking down GLP-1 from degrading it. A single weekly injection maintains a sustained level in the body, keeping those appetite and satiety signals active throughout the week rather than for a few minutes after a meal.

This is why semaglutide is classified as a GLP-1 receptor agonist rather than a hormone replacement or hormone therapy. It does not top up a deficiency; it uses a biological pathway your body already has, amplified and extended. If you have been wondering whether Wegovy contains GLP-1 itself or simply mimics it, we have answered that question in detail separately. The NHS semaglutide medicines page explains this mechanism in plain language if you want more detail on how it works at a patient level.

Does semaglutide affect other hormones in your body?

Semaglutide acts primarily at GLP-1 receptors, but those receptors are distributed widely, in the hypothalamus (a key appetite-regulation centre in the brain), the gut wall, and the pancreas. This broad distribution means semaglutide has downstream effects on several hormonal processes, even though it is not itself a hormone.

Insulin and glucagon are the clearest examples. GLP-1 receptor activation encourages the pancreas to release insulin when glucose is present and suppresses glucagon (the hormone that raises blood sugar). In people without diabetes, this happens in a glucose-dependent way, so the risk of blood sugar dropping dangerously low is small. Ghrelin, often called the hunger hormone, appears to be indirectly suppressed during treatment, which likely contributes to reduced appetite beyond the direct brain-signalling effect. Some research also suggests changes in peptide YY, another satiety-related gut peptide, though the clinical significance of this during Wegovy treatment is still being studied.

Importantly, semaglutide does not act on sex hormones, thyroid hormones, cortisol or the adrenal system in any licensed or described mechanism. If you are curious about the broader picture of how semaglutide interacts with the body's hormonal systems, we have covered that question in detail separately.

Should people on HRT or the contraceptive pill be aware of anything specific?

This is one of the practical hormonal questions that comes up most often. Semaglutide slows gastric emptying (the rate at which your stomach moves food and liquids into the small intestine) and this can theoretically reduce how quickly oral medicines are absorbed. The NHS England guidance on weight-management injections advises that people taking oral contraceptives while on semaglutide should be aware of this, though the clinical evidence of reduced pill effectiveness for semaglutide specifically is less established than for tirzepatide.

If you currently take HRT, NHS England suggests considering whether a transdermal form (patches or gel applied to the skin, which bypass the gut entirely) might be more appropriate while on treatment. The reasoning is precautionary rather than based on confirmed harm, but it is the kind of thing a prescriber will want to discuss with you before starting. You can read more about how Wegovy interacts with your body's hormone signalling on a dedicated page. The NHS England weight-management injections guidance covers the contraception and HRT points directly.

If you store your Wegovy pen in the fridge door alongside your morning supplements, it is worth keeping a note of your other daily medicines so a prescriber can review the full picture, small details like that can matter more than people expect.

Is Wegovy safe to take alongside existing hormone treatments, and who decides?

Wegovy is a prescription-only medicine, which means no one should be starting it without a clinical review of their full medical history, including any hormone treatments they are currently taking. That review is not a formality. A prescriber will consider your HRT type, your contraceptive method, any thyroid conditions on your record, and whether any adjustments to timing or formulation make sense before your first pen arrives.

The clinical trial evidence for Wegovy is substantial. The STEP 1 trial, published in the New England Journal of Medicine, showed an average weight reduction of around 15% over 68 weeks at the 2.4mg maintenance dose, in adults with obesity or overweight plus at least one weight-related condition. That evidence was generated in participants with a range of co-existing conditions, including people on various medications.

For context on what Wegovy treatment involves and the costs of private access, our Wegovy price comparison page covers what is typically included in a private prescription service and what to look for when comparing providers. If you want a broader overview of how Wegovy fits into the UK weight management landscape, the Wegovy treatment page is a good starting point. Questions about which hormone Wegovy is based on and how it works in the body are answered on a dedicated page if you would like to explore that before your consultation. Questions about whether you are personally suitable are best answered through a consultation with a prescriber who can look at your situation properly, that is exactly what our clinical team at nume does before any prescription is issued.

If you are ready to have those questions answered for your own circumstances, you can start your free consultation and a GPhC-registered prescriber will review your details the same day.