What to Do When Starting Wegovy: The Things That Actually Matter

The biggest myth: the starter dose should already be doing something visible

Most people starting Wegovy expect to see weight change quickly. When the scales don't shift in the first few weeks, some worry the treatment isn't working, and that worry is understandable, but the worry is based on a misreading of how the schedule works.

The 0.25mg starting dose is not a therapeutic dose. Its job is to let your body adjust to semaglutide's effects on the gut (slower gastric emptying, altered appetite signals) without overwhelming you with nausea. The dose escalates roughly every four weeks, guided by your prescriber, progressing through 0.5mg, 1.0mg, 1.7mg and eventually 2.4mg (or now up to 7.2mg for eligible patients, following the MHRA's approval of the higher-dose pen in April 2026). The meaningful appetite reduction and weight change tend to arrive as the dose climbs, not on day one.

The practical implication: treat the first pen as a settling-in period. Use it to build habits. Don't judge the medicine by what it does at 0.25mg. Our full Wegovy overview covers the complete dosing pathway and what the clinical trials reported at maintenance doses.

Knowing this also protects against a common mistake: some people raise their dose early, without prescriber approval, because they assume more is better sooner. It isn't, and doing so significantly raises the risk of the GI side effects you're trying to avoid.

The practical steps that shape the first injection and every one after it

A few habits, established from the first dose, make every subsequent week easier. First, pick a day of the week and keep it. Wegovy is a once-weekly injection; consistency matters not just clinically but practically, the same day each week becomes part of your routine rather than something you have to remember.

Injection sites are the abdomen, front of the thigh, or upper arm. Rotating between them each week reduces the chance of skin reactions at any one spot. The pen is stored in the fridge at 2–8°C; take it out a few minutes before you inject so the temperature isn't uncomfortable. For the exact storage window outside the fridge, the Patient Information Leaflet is the place to look, not a general website.

If you're on oral contraceptives, there is one specific thing worth knowing before you start. Preparation before your first dose matters here: for the first four weeks of Wegovy treatment and for four weeks after each dose increase, NHS guidance recommends adding a barrier method alongside the pill, because GLP-1 medicines can slow how the pill is absorbed. Talk to your prescriber if you're unsure whether this applies to you.

After the injection itself, dispose of the needle safely. A sharps container is the correct way to do this at home, not a household bin.

Eating and drinking alongside Wegovy from the first week

Wegovy suppresses appetite, but in the early weeks the most relevant dietary challenge isn't eating too much, it's eating enough of the right things when nausea makes food feel unappealing.

Protein becomes especially important. Rapid weight loss, including the weight loss these medicines can produce, carries a risk of muscle loss alongside fat loss. Keeping protein intake adequate helps preserve muscle mass; ongoing eating habits while on Wegovy matter throughout the treatment period, not just at the start. Aim for protein at every meal, even small ones: eggs, fish, chicken, Greek yogurt, lentils.

On the GI side effects: nausea, constipation and loose stools are all common in the early weeks, particularly in the first day or two after an injection. Small, frequent meals tend to fare better than large ones. Fatty, fried food and alcohol seem to worsen nausea for many people. Staying well hydrated matters, dehydration compounds GI symptoms.

The NHS patient information on semaglutide is clear that these GI effects are usually transient and most pronounced around dose changes. If vomiting or diarrhoea is severe or prolonged, contact your healthcare team: dehydration can become a problem, and in rare cases it can affect the kidneys.

A note on cost, if that's on your mind too: Wegovy pricing in the UK is worth understanding before you commit to a full course, since monthly costs vary by provider and dose.

When to contact your prescriber, and what warrants urgent help

Most side effects in the first weeks are uncomfortable rather than dangerous, but a few symptoms should prompt immediate action rather than a wait-and-see approach.

Severe abdominal pain (particularly if it's persistent and radiates towards your back, with or without vomiting) needs urgent medical attention. This symptom pattern can indicate acute pancreatitis, a known though infrequent side effect that the MHRA has highlighted specifically for GLP-1 medicines. The MHRA's Yellow Card scheme is where any suspected serious side effect should be reported, and you can also use it to report anything that seems unusual or unexpected from your treatment.

Beyond emergencies, your prescriber should hear from you if nausea is severe enough to stop you eating for more than a day or two, if you're unable to stay hydrated, or if you have any questions about whether your dose is right for your current situation. That is exactly what aftercare exists for.

If you're considering starting Wegovy and want a clear picture of what the process looks like from the beginning, or would like your current treatment reviewed, our guide on what to know when starting Wegovy can help you prepare before you speak to our prescribers, a real clinician reviews your consultation the same day, and there's no waiting list.