Preparing to Take Wegovy: What to Expect Before You Start

What the prescribing guidance actually says you should do first

The Wegovy Summary of Product Characteristics and NHS England's weight-management injections guidance are clear: semaglutide is prescribed alongside a reduced-calorie diet and increased physical activity, not as a replacement for them. Starting to adjust your eating pattern before dose one gives your digestive system a gentler introduction, and you can find practical steps for doing exactly that in our semaglutide preparation guide. High-fat, spicy and very large meals are the most common triggers for the nausea that arrives in the early weeks, so trimming portion sizes and keeping fat moderate before you begin makes the transition considerably easier.

You should also begin thinking about injection timing. Once-weekly means the same day each week works best for consistency. Some people choose a day they are mostly at home; others prefer a day they know they will remember. There is more practical detail on choosing the right moment in our guide to when to take your Wegovy injection.

If you are on oral contraceptives, tell your prescriber before starting. NHS England advises discussing contraception before beginning semaglutide, because slowed gastric emptying may affect how quickly oral medicines are absorbed — your prescriber may recommend a back-up method during the early titration period.

How to store and handle your pen before the first use

Your pen arrives tracked via DPD in plain, unbranded packaging, most people find this straightforward but it is worth knowing what you will find inside: a pre-filled injector device, a Patient Information Leaflet and a needle pack. Before you use it, the pen lives in the fridge at 2–8°C. The exact room-temperature window during which you can leave it out is specified in the Wegovy Summary of Product Characteristics on the eMC; follow that figure rather than anything you have read online, because incorrect storage affects how well the medicine works.

A few practical habits help. Keep the pen in its original packaging to protect it from light. Do not freeze it, and do not put it in the fridge door where temperature fluctuates. Sharps disposal matters too: arrange a sharps bin before your first injection rather than after. Never put used needles in household waste.

Change the needle for every injection, reusing needles increases the risk of blocked doses and infection at the injection site. Rotating between the abdomen, thigh and upper arm reduces local skin reactions over time. Detailed technique guidance is in the Patient Information Leaflet; if you are uncertain, your prescriber or our aftercare team can walk you through it. For aftercare queries, our support team is available seven days a week.

Realistic expectations: what the STEP 1 trial shows about the early weeks

The STEP 1 trial (published in the New England Journal of Medicine and involving nearly 2,000 adults with obesity) found that participants using semaglutide 2.4mg lost an average of around 15% of their body weight over 68 weeks. That headline figure is from people who had gone through the full titration schedule, most of whom experienced GI side effects in the early months. The first four to six weeks rarely show dramatic change on the scale; the 0.25mg starter dose is there to settle your system, not to produce rapid loss.

Side effects are most noticeable after starting or after a dose step: nausea, loose stools, constipation and fatigue are the most commonly reported. These typically ease within one to two weeks of each increase. Eating slowly, stopping when full and avoiding alcohol during the early titration period all help. If symptoms are severe or persistent, contact your prescriber, dose escalation is guided by how well you tolerate each level, not by a fixed calendar. Read more about the titration experience in our full semaglutide overview.

The evidence also shows that lifestyle support matters: trial participants received dietary and activity coaching alongside the medicine. Building even modest habits before you start (a daily walk, smaller plates, more protein at each meal) gives the medicine more to work with from week one.

Getting the practical admin right before your first dose

A few things are worth sorting before your pen arrives. Tell your GP that you are starting Wegovy; this keeps your medical record current and means your GP can flag any interactions with other treatments they manage. If you are considering what the treatment costs over time, our Wegovy cost page covers what a private prescription genuinely includes and what to watch for with providers who quote a headline price without the full picture.

Check your other medicines with your prescriber, particularly anything taken daily by mouth. Oral medicines taken within the 4–6 hours after a Wegovy injection may absorb differently as gastric emptying slows, your prescriber can advise on spacing. This includes thyroid medication, which is particularly time-sensitive.

Understand what surgery preparation requires too. If any planned procedure is coming up, your anaesthetist needs to know you are on a GLP-1 medicine; NHS England specifically flags this because of the risk of aspiration under general anaesthetic when gastric emptying is delayed. If you want a fuller checklist of everything to organise before you begin, our Wegovy prep page brings it all together in one place. Finally, if you have questions about how to bring Wegovy to work or travel with it, our guide on taking Wegovy to work covers storage away from home. A little preparation now removes most of the friction people encounter in the first few weeks.