Wegovy FAQs: Common weight loss questions answered

Wegovy (semaglutide) is one of the most widely used weight loss injections, and for many people it is the first medication they come across when exploring medical support for weight loss.

Understanding what it does, and what it does not do, can help you decide whether it is the right option for you.

Here are answers to some of the most common questions patients ask about Wegovy.

How does Wegovy work?

Wegovy contains semaglutide, which mimics a natural hormone called GLP-1 (Glucagon-Like Peptide-1) that helps regulate appetite and blood sugar after eating.

It works by reducing appetite, helping you feel fuller sooner, and slowing how quickly food leaves the stomach.

It also acts on areas of the brain involved in hunger and food reward, which can reduce cravings and what some people describe as “food noise” - the constant thoughts about eating.

Unlike some newer medications, Wegovy works through a single hormone pathway. For many people, this is still enough to produce significant changes in appetite and eating patterns.

Wegovy begins to act from the first dose, but you might not notice its effect immediately.

Most people start to see changes over several weeks, with more significant results developing over months.

In clinical trials, people taking Wegovy at well tolerated doses lost 10-15 percent of their body weight over approximately 68 weeks when combined with lifestyle support.¹

Don’t be disheartened if your weight loss seems to speed up and slow down over time. It is common to see fluctuations or plateaus along the way.

No, Wegovy and Mounjaro are not the same medication, although they’re both used to support weight loss and work in similar ways.

Wegovy contains semaglutide, while Mounjaro contains tirzepatide - a newer medication that targets two hormone receptors instead of one.

Both treatments help reduce appetite, control cravings, and support long-term weight management, but they may differ in terms of effectiveness, side effects, dosing, and suitability depending on your health history and goals.

The first week is usually about getting used to the medication.

Some people notice a change in appetite quite quickly. Others find the effect builds more gradually over time or when their dose increases.

You may experience:

• Feeling full more quickly.

• Reduced interest in snacks.

• Mild nausea (feeling sick) or bloating.

• Changes in bowel habits.

• Less “food noise”.

Weight loss may or may not occur straight away, but you might notice these other changes sooner.

The early phase is primarily about allowing your body to adjust to a new medication.

For most people, Wegovy is considered safe when prescribed and monitored by a healthcare professional.

Clinical trials have shown that it can support significant weight loss, along with improvements in metabolic health.^{2 3}

However, like any medication, safety depends on appropriate prescribing, careful dose adjustments, and ongoing monitoring.

Ideally before starting treatment, a doctor will review your:

• Medical history.

• Current medications.

• Metabolic health.

• Potential risk factors.

• Long-term goals.

Wegovy is not simply a weight loss product. It is part of a broader medical approach to improving metabolic health, which ideally should include support with nutrition, activity, sleep and behaviour change.

Wegovy is given as a once-weekly injection using a pre-filled pen. Each pen contains four doses, so it typically lasts for around one month.

To use the pen:

• Prepare the pen and attach a new needle.

• Prime the pen before first use.

• Select your prescribed dose.

• Inject into the skin at a right angle.

• Hold the pen in place briefly to ensure the full dose is delivered.

• Remove and safely dispose of the needle.

Your clinician or pharmacist will usually show you how to do this before your first injection and there will be clear instructions in the patient information leaflet that comes with the pen.

Wegovy is designed to be injected into the fatty layer just under the skin.

The usually recommended sites are:

• Abdomen, at least 5 cm away from the belly button.

• Thigh.

• Upper arm.

There is no single best site. The most important thing is that it is comfortable and easy to access.

Rotating injection sites is recommended to reduce the risk of irritation or bruising.

Before use, Wegovy pens should be stored in the fridge between 2°C and 8°C. Once opened or in use, they can be kept below 30°C or stored in the fridge, and should be used within 6 weeks.

Keep the pen cap on when not in use and avoid freezing the medication.

Wegovy can affect how some medications are absorbed because of direct interactions of how it slows stomach emptying. These include:

Insulin and sulfonylureas

These diabetes medications can increase the chance of hypoglycaemia (low blood sugar) when used alongside Wegovy.

You might need to reduce your usual dose or stop a medication altogether, so it’s important to speak with a doctor before starting treatment and as your weight loss progresses.

Medicines affected by slower stomach emptying

Because Wegovy slows gastric emptying, it can affect how quickly some medicines are absorbed. You might need dose adjustments or more frequent monitoring blood tests.

These include:

• Thyroid medications.

• Warfarin.

• Anticonvulsants.

• Immunosuppressants.

• Lithium.

• Digoxin.

Wegovy is a prescription-only medication and you should always tell your doctor about all medications and supplements you are taking.

The good news is that as your weight and metabolic health improve, you might find that you are able to reduce or stop other medications altogether. This should always be guided by your doctor.

For additional interactions with Wegovy, use our drug interaction checker.

The most common side effects of Wegovy are related to the digestive system, particularly when starting treatment or increasing the dose.

These include:

• Nausea and vomiting.

• Reduced appetite.

• Diarrhoea or constipation.

• Bloating, indigestion, and farting.

• Tiredness.

• Some hair thinning.

• Headache.

For most people, these symptoms are mild and improve as the body adjusts.

However, support can be helpful if symptoms are taking longer to settle or are marked. You might benefit from dietary guidance, slower dose increases, or occasionally short-term medications to manage symptoms.

If symptoms are severe or persistent, individual medical assessment is important to make sure it’s still safe for you to use your medication.

Data on long-term side effects of Wegovy are still developing, but current evidence suggests that Wegovy is generally well tolerated.²³

However potential long-term side effects include:

• Gallstones - particularly with rapid weight loss.

• Pancreatitis - which is rare.

• Some types of thyroid tumours.

• Worsening mental health.

• Loss of lean muscle mass if nutrition and physical activity are not optimised.

These risks are uncommon, but they highlight why ongoing medical supervision is important during treatment.

There is no strict rule against drinking alcohol while taking Wegovy.

However, it’s best to stick to a low level of drinking or avoid it altogether if possible as alcohol can:

• Worsen nausea or reflux.

• Affect appetite and food choices.

• Contribute additional calories.

Some people find that their desire for alcohol reduces while taking the medication, and that reducing their usual intake is fairly simple. This in turn can lead to further benefits such as improved sleep, mental health, and energy.

There is no specific diet that you must follow whilst taking Wegovy. However, what you eat can affect both your results and how you feel.

Many people find that their eating patterns shift naturally towards:

• Smaller portions

• Simpler meals

• Less rich or heavy foods

As your intake and relationship with food changes it can be helpful to focus on:

• Protein - to support muscle mass.

• Fibre - to support gut health and feeling fuller for longer.

• Whole foods - such as vegetables, fruits, legumes, and whole grains.

Wegovy can make it easier to change your diet, and this can be a great opportunity to develop a more balanced and sustainable relationship with food.

You can find more information on diet and food choices in our article Wegovy diet: Foods to eat and avoid.

It can be really frustrating if you aren’t losing weight as rapidly as you’d hoped after starting Wegovy.

Possible reasons include:

• Not yet reaching an effective dose.

• Eating patterns not changing significantly.

• High calorie liquids or easily consumed foods.

• Reduced physical activity.

• Individual variation in response.

• Temporary plateaus.

• Changes in body composition (fat loss with muscle gain).

But don’t forget that the number on the scale isn’t everything.

You might be making meaningful progress in metabolic health or body composition, even if your weight changes slowly. Other times, it might be that other factors – such as stress, poor sleep, or medications – are impacting your weight loss journey.

Regular check-ins with a clinician can help assess progress and adjust treatment if needed, and having lifestyle support whilst you use Wegovy can help you reach your weight and health goals.

Wegovy does not appear to have any adverse effects on fertility.

In fact, the weight loss and improved metabolic health associated with using Wegovy can sometimes increase fertility.

This is particularly evident in conditions such as PCOS, where obesity and insulin resistance can disrupt ovulation.⁴

This can sometimes be unexpected, so contraception should be considered if pregnancy is not planned.

If you are planning to conceive, it is usually advised that you stop using Wegovy at least two months beforehand to allow it to be cleared from your body.

And if you plan to become pregnant in the future, it is important that you use contraception whilst using Wegovy.

No, Wegovy is not recommended during pregnancy. This is primarily because there isn’t sufficient safety data assessing the potential impact on a baby.

If you become pregnant while taking Wegovy, speak to your healthcare provider as soon as possible.

When treatment stops, appetite signals often begin to return to their previous patterns.

For many people, that means feeling hungrier again, thinking about food more often, and finding it harder to maintain the same eating habits that helped you lose weight whilst taking Wegovy.

As a result, some degree of weight regain is common, particularly if the reasons behind your initial weight gain have not changed.

That said, the time spent on Wegovy can be incredibly valuable, and for many people it creates a window where decisions around food feel less effortful. That space can be used to build more sustainable patterns around eating, activity, sleep, and overall health.

Those changes are what make the biggest difference once treatment stops.