Wegovy starter dose: What to expect in week 1

Almost everyone approaches the first injection with the same two feelings: Relief that treatment has been approved, and a slight dread about actually starting it.

That combination is so common among first-timers that our prescribers expect it. Patients tell us afterwards that the pen was the easy part and the waiting was the hard part.

This guide covers what the first 7 days after starting the 0.25mg dose look like, from the injection shot to the day your second dose is due.

For every dose step from 0.25mg all the way up to 7.2mg, read Wegovy dosage schedule explained.

If GLP-1 medicines are new to you, start with our complete UK guide to GLP-1 medications.

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 6,553 reviews.

The starting dose is low on purpose.

Wegovy contains semaglutide, which slows how quickly your stomach empties and reduces appetite signals.

Introduce that effect at full strength, and the gut protests, usually with nausea. Introduce it gradually, and most people barely notice the adjustment.

The maintenance dose is reached by starting at 0.25mg, and the dose is increased every 4 weeks over 16 weeks to reduce the chance of stomach and bowel symptoms.

So the schedule looks like this:

• Weeks 1 to 4: 0.25mg once a week (your starter dose)
• Weeks 5 to 8: 0.5mg once a week
• Weeks 9 to 12: 1mg once a week
• Weeks 13 to 16: 1.7mg once a week
• Week 17 onwards: 2.4mg once a week, the standard maintenance dose

There is now also a higher 7.2mg option for people being treated for obesity, approved by the MHRA in January 2026, with a single-injection 7.2mg pen approved in April 2026.

That dose sits at the far end of the schedule and is only considered once someone has reached and tolerated 2.4mg, but the 2.4mg isn’t producing the desired results. It is not something to think about in week 1.

Three things happen quietly during week 1.

• Your stomach empties more slowly. Food sits longer in your stomach, which is why a normal-sized meal can suddenly feel like too much.
• Appetite signalling changes. Many patients describe it as food noise going quiet. The constant background thought about the next snack fades.
• Your body begins building up a steady level of the medicine. Semaglutide stays in the system for a long time, so the effect builds over the first few weeks rather than switching on and off between injections.

Those same changes are where the early side effects come from.

A stomach that empties more slowly is more likely to feel nauseous, which is why nausea is the most commonly reported side effect of Wegovy.

On 0.25mg, it is usually mild and passes within a day or two of the injection.

Some people also get constipation, tiredness, or a mild headache in the first week.

We map the whole arc, week by week, through every dose step in Wegovy side effects week by week.

What the 0.25mg dose is not doing is driving meaningful weight loss. That is not a flaw in the dose, it is the design of it.

Patients who understand this in advance tend to have a much calmer first month than patients who weigh themselves on day 7, expecting a result.

The pen is designed to be used by someone who has never injected anything before.

• Take the pen out of the fridge a short while before. Injecting medicine straight from the fridge is more likely to sting. Twenty to thirty minutes on the worktop is enough.
• Choose your site. Wegovy goes into the fat just under the skin of the stomach area, the front of the thigh, or the back of the upper arm. Stay at least 5cm (about 2 inches) away from your belly button and rotate the spot each week.
• Attach a fresh needle. A new needle every single time, and never share a pen with anyone.
• Inject and hold. Press and hold the button until the counter returns to zero, then hold a few seconds longer so the full dose goes in.
• Dispose of the needle in your sharps bin. Your sharps bin comes with your order.

The needle supplied is very short and fine, and most people describe the injection as a scratch rather than a jab.

Patients who were most nervous beforehand are usually the ones who message afterwards to say it was nothing like they imagined.

You can inject at any time of day, with or without food. Pick a day that suits your week and keep it.

Where to keep the pen between injections. Until you use it for the first time, your pen belongs in the fridge, between 2°C and 8°C.

Once you have started it, the pen can stay in the fridge or sit at room temperature below 30°C, so either is fine for the four weeks you will be using it.

If a delivery ever arrives warm and you are not sure the pen is still usable, check with us before you inject.

Everyone is a bit different, but the pattern below is the one patients describe most often.

Plenty of people have a first week that looks nothing like this, and that is still normal.

Some people sail through with no symptoms at all on 0.25mg, and a smaller number of people finds the first week harder than average.

Both are common, and neither predicts how the rest of your treatment will go.

Here is the honest picture from the trial data, with one important caveat attached.

The figures below come from the four STEP trials that led to Wegovy being licensed, known as STEP 1 to STEP 4, which followed 2,650 adults for 68 weeks.

Those 68 weeks cover the 16-week climb through the dose steps, plus a year at the full 2.4mg maintenance dose, so these are not week 1 numbers.

No separate figure has been published for how often each side effect occurs during the 0.25mg weeks on their own.

Two things are worth pulling out of that table.

• Symptoms cluster around dose increases, not around the low starter dose. The product information states these effects are mainly seen during the dose-escalation period, and most are mild to moderate and short-lived.
• A meaningful number of people on the placebo reported the same symptoms. Around one in six reported participants nausea on the placebo, which is a useful reminder that not every twinge in week 1 is the medicine.

Constipation is the exception. It tends to last longer than the other symptoms, which usually pass within a day or two.

Often very little, and that is the expected result.

Weight loss on Wegovy builds as the dose climbs.

In the STEP 1 trial, participants on the full 2.4mg maintenance dose lost an average of 14.9% of their body weight by week 68, compared with 2.4% on placebo, and around 86% of participants lost at least 5% of weight.

Those results came from months of treatment at higher doses, not from week 1 at 0.25mg.

Some people do see a small drop in the first week.

It is usually water and a genuinely smaller food intake rather than fat loss, and it is not a prediction of anything.

A more useful early marker than the scales is whether your appetite has changed.

That is the sign the medicine is doing what it should at this stage.

For the full timeline of when the weight tends to move, read how long it takes to lose weight on Wegovy.

Prescribers generally review progress at around six months, where the standard benchmark is at least 5% weight loss of their starting body weight.

Week 1 is far too early to judge.

If you weigh yourself, do it once a week, same day, same time, before breakfast.

Daily weighing in week 1 tends to cause worry rather than provide information.

None of this is complicated, and most of it is about working with the slower stomach rather than against it.

• Make meals smaller and eat more slowly. Your old portion size is the single most common cause of week 1 discomfort.
• Go easy on very fatty and very rich food for the first few days after the injection. Fat is slow to leave the stomach at the best of times.
• Increase fluid intake. This matters for constipation, and it matters more if you have any vomiting or diarrhoea, because dehydration is the thing that turns a manageable side effect into a problem.
• Get protein in early in the day while your appetite is at its most cooperative.
• Be careful with alcohol. There is no ban on it, but it can make nausea worse, and it is easy to underestimate now that you are eating less.

Both of these come up constantly in week 2, so it is worth knowing the rules before you need them.

• Missed a dose by up to five days? Take it as soon as you remember, then go back to your normal weekly day.
• More than five days late? Skip that dose entirely and take the next one on your usual scheduled day. Do not double up.
• Want to move your injection day? You can, as long as there are at least three days between one injection and the next. After that, carry on weekly from the new day.

Most of what happens in week 1 is mild and settles on its own. A few things do not, and these are the ones to act on straight away.

Seek urgent medical help if you have:

• Severe stomach pain that does not go away, especially if it spreads to your back or comes with vomiting. This can be a sign of pancreatitis, which is rare but serious.
• Sudden loss of vision or eyesight that gets rapidly worse. It could be a rare eye condition called NAION and it needs to be assessed quickly.
• Swelling of the face, lips, or throat, or difficulty breathing, which can signal a serious allergic reaction.
• Vomiting or diarrhoea that stops you from keeping fluids down, or that leaves you dizzy and passing very little urine.

Contact your prescriber, without urgency, if:

• Nausea is stopping you from eating or working.
• Constipation has not shifted after several days of more fluid and fibre.
• You have pain under your ribs on the right side, which can point to gallstones.
• You take insulin or a sulphonylurea for diabetes, and you are getting symptoms of low blood sugar, because those doses may need adjusting.

Tell any healthcare professional treating you that you are on a GLP-1 medicine, especially before an operation or sedation, because the MHRA advised in January 2025 that these medicines can raise the risk of stomach contents entering the lungs under anaesthetic.

Do not stop your treatment yourself before a procedure. Tell the medical team and let them advise you on it.

Wegovy is also not for use in pregnancy. The MHRA advised in June 2025 that women who could become pregnant should use effective contraception while on GLP-1 treatment, and semaglutide should be stopped at least two months before trying to conceive.

The rule is similar for Mounjaro, and in one way stricter, because tirzepatide, the active ingredient in Mounjaro, can make the contraceptive pill less reliable.

If you take Mounjaro, or you are considering it, our Mounjaro and contraception guide covers what changes.

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

Wegovy carries a black triangle, which means the MHRA is still actively collecting safety data on it, and patient reports genuinely feed into that.

Assuming week 1 to week 4 go reasonably well, your dose steps up to 0.5mg in week 5.

That step is usually where people notice a small return of the early nausea for a couple of days, then it settles again.

The same pattern repeats at each increase, which is why the schedule spaces them four weeks apart.

If the first four weeks have been difficult, tell your prescriber before the step up.

Staying on the starter dose for an extra cycle is a normal clinical decision, not a setback, and it is often the difference between someone continuing treatment comfortably and someone giving up in month two.

A few things have moved in the last year, and you may have seen some of them in the news.

• A higher 7.2mg dose is now available for people treated for obesity, following MHRA approval in January 2026 and a single-injection pen in April 2026.
• A pill version of semaglutide for weight loss, called the Wegovy pill, has been approved in the UK, which will interest anyone who would rather not inject. It is a different product from Wegovy and not a swap you can make in week 1, but the option now exists.
• Wegovy has a second licensed use. Alongside weight management, it is licensed to reduce the risk of heart attack and stroke in adults with established cardiovascular disease and a BMI of 27 or above, following MHRA approval in July 2024 and a NICE recommendation in 2026. We cover that in Wegovy and heart disease.
• The MHRA has repeatedly warned about fake weight loss pens sold through social media and beauty salons. Some have been found to contain insulin instead of semaglutide, and people have been hospitalised. Anything prescribed through a GPhC-registered pharmacy after a proper consultation is a different thing entirely.

Straightforward, from start to finish:

1. Fill in a short medical questionnaire. It takes 5 to 10 minutes and covers your medical history, current medicines, height and weight, and any allergies. The questions are thorough on purpose, because a prescriber uses them to check if the treatment is safe for you.
2. A GMC-registered prescriber reviews your answers. If they need more details, they message you through your account.
3. If Wegovy is suitable, it is dispensed and dispatched for next-day delivery, with your needles, sharps bin, and the full patient information leaflet included.
4. If it is not suitable, the prescriber explains why, and you are not charged for treatment that is not issued.

Our prices for Wegovy start from £69.99, and that includes the consultation, the prescription, packaging, and delivery. There are no hidden fees.

Eligibility follows the licensed criteria: A BMI of 30 or above, or a BMI of 27 or above alongside a weight-related condition such as high blood pressure, type 2 diabetes, sleep apnoea, fatty liver disease, or heart disease.

Wegovy is a prescription-only medicine for adults, and our prescribers will tell you plainly if it is not the right treatment for you.