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Wegovy side effects tend to follow the dose ladder rather than the calendar. Each step up brings a short adjustment period.
Short answer

Most Wegovy side effects are digestive, so nausea, constipation, diarrhoea, and occasional vomiting are at their strongest in the first week or two after each dose increase.

They usually settle as your body adjusts.

That is exactly why the Wegovy dose starts low at 0.25mg and only steps up every four weeks.

In the pooled STEP trials, most digestive side effects were mild or moderate, and around 4 in 100 people stopped treatment because of them.

The timeline below walks through what most people notice, week by week, from the first injection through to the newer 7.2mg dose.

What's in this article

What most people are actually worried about

Most people worry about Wegovy’s side effects. This is normal. This is also one of the main reasons why they spend weeks deciding whether to begin at all.

That hesitation is fair.

You are being asked to inject a prescription medicine into yourself once a week, and the patient leaflet reads like a list of everything that could possibly go wrong.

Here’s the truth. Most Wegovy side effects are uncomfortable, but not dangerous.

They are strongest at the beginning, and after each step up, and for the large majority of people, they fade over time.

A small number of side effects are serious and need urgent attention, and those are set out clearly further down, with the symptoms to watch for.

This guide covers the whole picture in order: What some of the most common and most serious Wegovy side effects, why they happen when they do, what most people notice at each dose from 0.25mg up to 7.2mg, how common each side effect is, what actually helps, and the symptoms that should make you speak to someone straight away.

Before you begin: A little bit about OnlineClinic

OnlineClinic has been operating since 2011 and has treated more than 2.1 million patients.

The pharmacy is registered with the General Pharmaceutical Council (GPhC), our prescribers are registered with the General Medical Council (GMC), and the service is regulated by the Care Quality Commission (CQC).

As of August 2026, on Trustpilot, the service rating is 4.6 out of 5 based on 6,557 reviews.

Mounjaro side effects week by week Compare Mounjaro vs Wegovy

Why Wegovy side effects follow the dose, not the schedule

Wegovy’s active ingredient, semaglutide, mimics a gut hormone called GLP-1.

GLP-1 tells your brain you are full, and it slows down how quickly food leaves your stomach.

The slowed stomach emptying reduces appetite, and that same slowed stomach is what produces the nausea, the fullness that lingers, the reflux, and the constipation.

Two patterns follow from this, and both are useful to know in advance.

  • Side effects cluster around dose increases, not around any particular week of the year. Every time the dose goes up, your gut receives a stronger signal. The first week or two on a new dose is usually the peak, and things tend to level off across weeks three and four.
  • The very first weeks are the steepest learning curve. Before your first injection, your gut has never encountered semaglutide. Even at the low 0.25mg starter dose, plenty of people notice a change.

In the pooled analysis of the STEP 1 to 3 trials, digestive side effects were most common every time the dose was increased, and for the number of people experiencing their first dose, they levelled off after around week 20, which is roughly when the increase in doses comes to a halt.

Here's the good part

In that same pooled analysis, 98% of digestive side effects were mild or moderate, and 95.5% of the people who had the side effects still completed the trial.

Feeling rough for a few days after a dose increase is common. Having to stop is not.

The Wegovy dose schedule

Wegovy is not a fixed dose.

It climbs in stages, and each stage has its own short adjustment period.

Here is the standard UK schedule.

Your prescriber can slow it down at any point.

Stage Dose Typical timing Notes
1 0.25mg once weekly Weeks 1 to 4 Starter dose, not a treatment dose
2 0.5mg once weekly Weeks 5 to 8 First dose increase
3 1mg once weekly Weeks 9 to 12 The dose where changes in weight are mostly visible
4 1.7mg once weekly Weeks 13 to 16 Some people stay here for the long term
5 2.4mg once weekly Week 17 onwards The long-standing maintenance dose
6 7.2mg once weekly Week 21 onwards, if suitable Higher maintenance dose, licensed in the UK since January 2026

The MHRA (Medicines and Healthcare products Regulatory Agency) confirmed this pattern when it authorised the 7.2mg dose.

Treatment starts at 0.25mg per week, and the dose is increased every four weeks as your prescriber judges appropriate, up to a maximum of 7.2mg.

You do not have to reach the maximum dose on Wegovy.

Plenty of people lose the weight they want at 1.7mg or 2.4mg and stay there.

The aim is to find and stick to the lowest dose that works for you, not the highest one you can tolerate.

There is more detail on each step in our Wegovy dosage schedule guide.

Wegovy side effects: What to expect week by week

The timeline below draws on the STEP trial programme, the STEP UP trial for the 7.2mg dose, and the Wegovy UK product information.

Individual experiences vary quite a lot, so treat this as the common pattern rather than a forecast for you specifically.

Weeks 1 to 4

Starting at 0.25mg

The first injection is the moment most people build up in their heads, and almost everyone says afterwards that it was less dramatic than expected.

The needle is short and very fine. Most people describe a brief pinch. Some feel nothing at all.

Then the waiting begins.

Side effects arrive fairly quickly, usually within 24 to 72 hours of the injection, and then ease off before the next one is due.

That pattern repeats every week, and it is why so many people can name their "bad day".

What usually turns up in those first few days, and again after each injection:

  • Mild nausea, most noticeable one to three days after the injection. People often compare it to travel sickness or the queasiness of early pregnancy.
  • Reduced appetite, which is a sign that the medicine is working rather than a side effect, though it can feel strange if you are used to eating at set times.
  • A full feeling that lasts longer than usual after meals, sometimes with burping.
  • Constipation, or less often, loose stools.
  • Mild headache or tiredness, usually linked to eating and drinking less rather than to the medicine itself.

What most people do not see in this first month is a dramatic weight change. At 0.25mg, the dose is deliberately too low to do much. It is there to introduce your gut to semaglutide gently.

Quick tip

Pick your injection day with the rest of your week in mind. If any queasiness is going to arrive, it usually does one to three days later.

A lot of people inject midweek, so that the worst days fall on a weekend, and they can manage it with relative ease.

Weeks 5 to 8

Moving to 0.5mg

The Wegovy dose doubles here, and for many people, this is the first time they properly feel the medicine working.

What’s common at this stage:

  • Nausea often returns for a week or so, even if it had settled at 0.25mg. It is usually milder the second time round.
  • Appetite drops more noticeably. Portions that felt normal in week one can suddenly feel like too much.
  • Constipation becomes a more common complaint for a lot of people, more so than nausea.
  • Reflux or heartburn can appear, especially after having rich or fatty meals.

By the end of week eight, though, most people have settled and have started to work out their own pattern.

Weeks 9 to 12

At 1mg

The dose increase to 1mg follows the same pattern as the previous doses, generally with less drama, because your body now has two months of experience with semaglutide.

This is usually the stage where weight change becomes visible rather than theoretical. Clothes fit differently, and the appetite reduction feels less like a novelty and more like a new normal.

The side effects you have at this dose are usually the ones you will keep having at higher doses.

They do not tend to change in character. What changes is the intensity, and only for a week or two after each increase.

Weeks 13 to 16

At 1.7mg

By now, most people can predict what their own week will look like following a dose.

They know when the queasiness arrives, which foods cause trouble, and how much they can comfortably eat in one sitting.

This is also a genuine decision point rather than an automatic step.

If the weight is coming off steadily at 1.7mg and you feel well, there is no rush to go higher.

Some people stay on 1.7mg as their long-term dose and do perfectly well on it.

Week 17 onwards

At 2.4mg

The 2.4mg has been the standard Wegovy maintenance dose since it was licensed, and it is the dose behind the familiar headline figures.

In the STEP 1 trial, adults taking 2.4mg alongside lifestyle changes lost an average of just under 15% of their starting body weight over 68 weeks.

The adjustment period at 2.4mg is usually the same story as the previous doses. A week or two of stronger nausea or constipation, and then, things level off.

What happens after that is more encouraging than people expect.

In the pooled STEP analysis, the number of people reporting nausea, diarrhoea, and constipation fell steadily the longer they stayed on a stable dose. For a lot of people, week 17 looks nothing like week 1.

Did you know

There is no evidence that pushing through worse side effects gets you better results.

In the same pooled STEP analysis, researchers looked at whether the weight loss was being driven by feeling sick, and found that the vast majority of it was not.

Feeling well and losing weight are not opposites.

Week 21 onwards: What changes at the 7.2mg dose

This is the newest part of the picture, and the part where UK information is still catching up.

The MHRA approved a maximum weekly Wegovy dose of 7.2mg on 16 January 2026.

At first, it had to be given as three separate 2.4mg injections on the same day.

On 14 April 2026, the MHRA approved a single-dose 7.2mg pen, so the full dose is now one injection.

The higher 7.2mg dose is licensed for adults with a BMI (body mass index) of 30 or above, and it is not licensed for people using Wegovy at a BMI under 30, or for reducing cardiovascular risk.

It is also not a starting dose. You reach it only after tolerating the 2.4mg dose, but not seeing the desired results on it.

The evidence comes from the STEP UP trial, which followed 1,407 adults for 72 weeks.

A bar graph showing the results of the STEP UP trial

Nearly half of the 7.2mg group lost 20% or more of their body weight, and close to a third lost 25% or more.

The side-effect trade-off is more nuanced than "stronger dose, worse side effects". Here is what the trial actually found.

Wegovy 7.2mg vs 2.4mg vs Placebo

STEP UP trial · 1,407 adults · 72 weeks

Reported digestive side effects

7.2mg
70.8%
2.4mg
61.2%
Placebo
42.8%

Had a serious adverse side effect

7.2mg
6.8%
2.4mg
10.9%
Placebo
5.5%

Reported altered skin sensation

7.2mg
22.9%
2.4mg
6.0%
Placebo
0.5%
7.2mg 2.4mg Placebo

Three things stand out from those numbers.

Digestive side effects were more common on the higher dose, but the gap is smaller than most people expect, and very few people stopped treatment because of them.

Serious adverse events were not higher at all.

Dysaesthesia is the clinical term, and it simply means altered skin sensation.

People describe tingling, a pins-and-needles feeling, numbness, or skin that feels oddly sensitive to touch, often in the hands, feet, or scalp.

Reading the word cold is alarming. The reality usually is not.

In the STEP UP trial, most of these events resolved during the trial without the dose being reduced.

Worth knowing

If you notice tingling or unusual skin sensitivity after moving to 7.2mg, tell your prescriber rather than assuming it is unrelated.

It is a recognised effect at this dose. It is usually temporary, and there are sensible options, including holding at 2.4mg for longer.

How common is each Wegovy side effect

The figures below are pooled from the STEP 1 to 3 trials of the 2.4mg dose, which remains the best-studied dose.

A bar graph showing how common each side effect is on Wegovy 2.4mg

They describe how many people reported each effect at some point across 68 weeks, not how many feel it every week.

Side effect Roughly how many people When it usually shows up Does it ease?
Nausea 44 in 100 Days 1 to 3 after a dose increase Yes, usually within 1 to 2 weeks per dose
Diarrhoea 30 in 100 First 2 weeks of a new dose Yes
Vomiting 25 in 100 Days 1 to 3 after a new dose Yes, usually within 2 weeks
Constipation 24 in 100 Weeks 2 to 6 of a dose, can linger Often, with fluids and fibre
Headache 14 in 100 Early weeks and after increases Usually, once eating and drinking settles
Altered skin sensation 6 in 100 at 2.4mg, 23 in 100 at 7.2mg After reaching the higher dose Usually, without changing the dose
Reduced appetite Very common From the first weeks, ongoing No, this is the intended effect
Fatigue, dizziness, burping, bloating Common Early weeks Usually, within a few weeks
Hair thinning Uncommon Around months 3 to 6 Usually, and it regrows

Sources: Pooled STEP 1 to 3 analysis, STEP UP, and the Wegovy UK SmPC.

A note on hair thinning:

Hair thinning is generally linked to losing weight quickly, rather than to semaglutide itself, and it is the same temporary shedding that follows any rapid weight loss.

It almost always resolves without stopping treatment.

How to handle the common Wegovy side effects

None of this is complicated. Here’s how you can handle the most common Wegovy side effects.

For nausea

  • Eat foods in smaller amounts. Big meals make the slowed-stomach effect much more obvious.
  • Stay upright for a while after eating, rather than lying down.
  • Go easy on very rich or very fatty food in the first few days after an injection.
  • Plain food is usually kinder to the stomach than complicated food. Toast, crackers, plain rice, and plain chicken are the standbys.
  • Ginger or peppermint tea helps some people. The evidence is thin, but there is no harm in trying.

For constipation

  • Hydrate yourself adequately. Slower digestion means fluid gets absorbed more thoroughly.
  • Increase fibre intake gradually. Adding a lot at once tends to swap constipation for bloating.
  • Walk daily if you can. Gentle movement genuinely helps.
  • If constipation persists after two weeks, mention it to your prescriber. A short course of a laxative is sometimes appropriate.

For diarrhoea

  • Have smaller, plainer meals for a few days.
  • Increase fluid intake, and use an oral rehydration solution if it lasts more than a day.
  • Cut back on coffee, alcohol, and spicy food in the first week of a new dose.
  • If it is severe or lasts more than a few days, contact your prescriber rather than waiting it out.

For reflux and indigestion

  • Eat your last meal earlier in the evening.
  • Stay upright for two to three hours after eating.
  • Very acidic, very fatty, and very spicy foods usually cause and worsen reflux and ingestion. Either reduce or avoid such foods.
  • Smaller and slower meals tend to help more than over-the-counter remedies.

For headaches and tiredness

  • Check you are drinking enough fluid. Mild dehydration may cause early headaches, because Wegovy blunts thirst as well as appetite.
  • Check you are eating enough. A pattern we see often around week 4 to 6 is "I have been eating far less, and now I am exhausted", and the answer is usually to eat a bit more, not less.
  • Protein with each meal helps steady both energy and blood sugar.
  • If tiredness persists, it is worth your checking iron, B12, and vitamin D levels.

For injection-site reactions

  • Rotate the site each week between the abdomen, front of the thigh, and back of the upper arm.
  • Take the pen out of the fridge 15 to 30 minutes before injecting. Cold injections sting more.
  • A small bump or patch of redness for a day or two is normal. Anything that spreads, blisters, or is still there after three or four days should be looked at.

Wegovy pens are stable below 30°C, which is why we ship them in standard insulated packaging rather than with an ice pack.

Mounjaro pens still need cold packaging. If you want more details on storing pens safely, see our guide to handling GLP-1 medicines at home.

The side effects that need urgent attention

While most Wegovy side effects are common and fade away with time, there are some side effects that require urgent attention.

Seek medical advice urgently if you notice these side effects:

  • Acute pancreatitis, which means inflammation of the pancreas. The signal to act on is severe, persistent stomach pain, usually in the upper abdomen and often spreading through to the back, sometimes with nausea and vomiting. Stop the medicine, and seek urgent medical advice.
  • Gallbladder problems, including gallstones. Rapid weight loss of any kind raises the risk of gallstones. Watch for sudden pain in the upper-right abdomen, sometimes with fever, or yellowing of the skin or the whites of the eyes.
  • Low blood sugar, particularly if you also take insulin or a sulfonylurea to lower blood glucose levels. Watch out for shakiness, sweating, sudden hunger, confusion, or feeling dizzy. Your prescriber will adjust those medicines if needed.
  • Serious allergic reaction. Rare, but swelling of the face, lips, tongue, or throat, a severe rash, or difficulty breathing needs emergency help immediately.
  • Dehydration and kidney problems, almost always caused by severe vomiting or diarrhoea. Keep fluids up, especially in those first days after a dose increase.
  • Worsening diabetic eye disease in people who already have diabetic retinopathy. Keep an eye out for blurred vision, new floaters, or dark spots. Your prescriber will ask about your eye health at the consultation.

On 29 January 2026, the MHRA strengthened the warnings on acute pancreatitis across the whole GLP-1 class, after rare reports of severe cases.

It is worth putting the numbers in proportion.

Between 2007 and October 2025, the MHRA received 1,296 Yellow Card reports of pancreatitis across all GLP-1 medicines, against an estimated 25.4 million packs dispensed in the UK over five years.

The risk is small.

The advice is simply to recognise the symptoms and act quickly if they appear.

You can report any suspected side effect yourself through the MHRA Yellow Card scheme.

When to message your prescriber

Get in touch with the prescriber through your account if:

  • A side effect has not eased after two weeks at a new dose
  • Nausea or vomiting is stopping you from eating or drinking properly
  • You have persistent stomach pain, as opposed to general discomfort
  • You notice tingling, numbness, or unusual skin sensitivity, particularly on 7.2mg
  • Any of the urgent symptoms from above appear
  • You are thinking about stopping because of side effects

What happens when you order from OnlineClinic

Our process is straightforward. From start to finish, this is what happens when you order with us:

  1. Fill in the medical questionnaire. It takes 5 to 10 minutes. For anyone with a cardiac history, answer the heart-related questions in full, including dates of events, procedures, and every current medicine. The questions are thorough on purpose
  2. A GMC-registered prescriber reviews your answers. If they need more details or want confirmation from the clinician managing your heart, they will message you through your account
  3. If treatment is approved, it is dispensed and dispatched. Next-day delivery, with needles, a sharps bin, and the full patient information leaflet included. Wegovy pens are stable below 30°C and ship in standard insulated packaging
  4. If it is not approved, the prescriber explains why. You are not charged for treatment that is not issued

Our Wegovy prices start at £69.99, and every price includes the prescription, the consultation, the packaging, and delivery. There are no hidden fees.

We prescribe Wegovy for weight management following an online consultation.

Where you have a cardiac history, our prescribers will often want your GP or cardiology team involved, and may decline to issue treatment online if they judge that ongoing in-person monitoring is the safer route.

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More than 2.1M patients treated

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Frequently asked questions

When do Wegovy side effects start?

How long do Wegovy side effects last?

Are the side effects worse at 0.5mg than 0.25mg?

Is Wegovy 7.2mg harder to tolerate than 2.4mg?

What is dysaesthesia, and should I be worried about it?

Can I stop Wegovy if the side effects are too much?

Do the side effects mean Wegovy is working?

Does Wegovy cause hair loss?

Does it matter what day or time I inject?

Is OnlineClinic safe to use for Wegovy?

Trial evidence

  • Wharton S et al. Once-weekly semaglutide 7·2 mg in adults with obesity (STEP UP): a randomised, controlled, phase 3b trial. The Lancet Diabetes & Endocrinology, 2025. Read the trial
  • Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). New England Journal of Medicine, 2021. Read the trial
  • Wharton S et al. Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg in adults with overweight or obesity. Diabetes, Obesity and Metabolism, 2022. Read the analysis

UK regulatory and product information

Disclaimer

Wegovy is a prescription-only medicine. Whether it is suitable for you is a decision made by a GMC-registered prescriber, based on your individual medical history. The information here is general guidance, and it is not a substitute for professional medical advice.

Further reading

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