A standard Wegovy pen delivers 4 once-weekly doses, so it lasts 4 weeks when used at the licensed UK dosing schedule. Its storage life is different, however, because an opened pen has a 6-week in-use shelf life, while an unopened refrigerated pen can be used until its printed expiry date.

You may be asking this after collecting your first pen and noticing that the answer seems less straightforward than “one month”. Perhaps you're counting the liquid in the window, planning a holiday, or wondering whether a missed injection means the pen can be kept for longer.

The word last has three meanings here:

• How many weekly doses the pen delivers.
• How long it remains usable after the first dose.
• How long an unopened pen can be stored before its expiry date.

For standard UK treatment, the practical answer is four weekly injections. That matches the way Wegovy is prescribed during dose escalation, with each stage arranged in four-week blocks. It doesn't mean you should use the pen until the visible liquid disappears, and it doesn't mean every possible Wegovy regimen consumes pens in exactly the same way.

The newer UK 7.2 mg pathway also changes the calculation for a specific group of adults with obesity. Patients prescribed that higher weekly dose use three 2.4 mg injections to make one weekly dose, so the familiar relationship between one pen and four weeks no longer applies in the same way.

The simple rule: Count the prescribed doses first, then check the pen's storage limit. Dose duration and medicine shelf life aren't the same thing.

If you're comparing treatment options or trying to understand the wider UK service pathway, the UK Wegovy treatment guide provides broader context. The rest of this article focuses specifically on pen duration, dosing stages, storage, travel and continuity of treatment.

Table of Contents

• Introduction to How Long a Wegovy Pen Lasts in the UK
  • Why the four-week answer usually applies
  • The exception readers often miss
• What a Wegovy Pen Contains and How Dosing Works
  • The basic sequence
• Understanding the UK Dosing Schedule and Pen Duration
  • Reading the titration as a calendar
  • Why weekly consistency matters
• How Long a Wegovy Pen Lasts After Opening and in Storage
  • Opened versus unopened pens
  • What counts as first use
• Why the New 7.2 mg Dose Changes How Long a Pen Lasts
  • Who this applies to
  • Why the calculation changes
• Practical Tips for Calculating Doses Handling Travel and Disposal
  • A reusable monthly check
  • Travel and missed injections
  • Disposal
• Key Takeaways for Planning Your Next Wegovy Pen

Introduction to How Long a Wegovy Pen Lasts in the UK

A standard UK Wegovy prefilled pen is built to deliver four once-weekly doses. At the usual licensed dosing schedule, that means one pen covers four weeks of treatment, even if you can still see some solution afterwards. The NICE information on semaglutide describes the UK pack format as one pen delivering four doses.

That format makes the pen easier to understand if you think of it as a four-week calendar rather than a bottle of liquid. You use one prescribed dose on your chosen injection day, repeat that weekly, and complete the pen after the fourth dose.

The confusion starts because people use “last” to mean different things. A pen may contain four treatment doses, yet remain within its permitted in-use period for six weeks after first use. An unopened pen has another rule altogether, because refrigeration allows it to remain usable until the expiry date printed on the label.

Why the four-week answer usually applies

The UK dose-escalation plan begins with 0.25 mg once weekly for weeks 1 to 4. The dose then increases in four-week stages through 0.5 mg, 1 mg, 1.7 mg and, for standard maintenance, 2.4 mg once weekly. Each stage therefore lines up neatly with one four-dose pen.

That alignment helps with prescription planning, but it doesn't give you permission to stretch or split doses. The pen's labelled delivery system and your prescribed schedule determine how it should be used.

The exception readers often miss

The standard answer applies to the usual treatment pathway, not every higher-dose situation. On 6 January 2026, the MHRA approved a maximum Wegovy dose of 7.2 mg weekly for adults with obesity. That regimen uses three 2.4 mg injections to make one 7.2 mg weekly dose, which changes how quickly pens are consumed.

You shouldn't apply that higher-dose calculation unless a prescriber has specifically moved you to the 7.2 mg pathway. For everyone following standard titration or 2.4 mg maintenance, the practical dosing answer remains one pen for four weekly injections.

What a Wegovy Pen Contains and How Dosing Works

Wegovy is supplied in the UK as a prefilled FlexTouch pen containing semaglutide. Semaglutide is a GLP-1 receptor agonist, meaning it acts on the same broad hormonal pathway involved in appetite regulation and digestion. The medicine is administered as a subcutaneous injection once weekly, rather than as a separate pen for every injection.

A useful analogy is a four-slot weekly planner. Each slot represents one injection day. The pen is designed to release the prescribed amount into each slot, so its treatment duration comes from the number of labelled doses, not from judging how much liquid appears to remain.

The basic sequence

1. Choose the prescribed weekly dose. Your clinician sets the strength according to the UK escalation schedule and your response to treatment.
2. Use the pen on the same weekly day. A regular day makes it easier to remember injections and identify when the next pen will be needed.
3. Count four completed injections. The fourth prescribed dose completes the standard pen's treatment cycle.
4. Discard the pen after dose four. The UK patient information says the pen should be discarded after the fourth dose, even if solution remains visible. The Wegovy patient information leaflet is the relevant reference for this instruction.

The remaining liquid can be misleading. A small visible amount doesn't necessarily represent a complete, accurate or authorised additional dose. Trying to extract more medicine can also interfere with dose accuracy and safe needle handling.

A visible remainder is not the same as an available dose. The pen's four-dose design takes priority over what you can see through the window.

The pen also shouldn't be treated as a short course that ends after a single month. The clinical evidence behind the licensed maintenance approach includes the STEP 1 trial, which followed adults with overweight or obesity without diabetes for 68 weeks while evaluating weekly semaglutide 2.4 mg against placebo. The UK-relevant STEP 1 summary describes the study as showing substantially greater weight-loss efficacy than placebo over that period.

That evidence matters because it places the pen in context. Each device is the delivery method for a weekly treatment plan that may continue over time under clinical supervision. The device lasts four doses, while the overall treatment decision depends on your prescriber, your health and how you respond.

For practical administration support, use the guide to using a Wegovy pen, and contact your prescriber or pharmacist if the device doesn't appear to work as expected.

Understanding the UK Dosing Schedule and Pen Duration

The UK dosing schedule is easiest to follow as a sequence of four-week blocks. Each block uses one prescribed strength, with one weekly injection during each week. The pen therefore matches the stage, rather than representing an arbitrary amount of medicine.

Reading the titration as a calendar

The licensed UK schedule starts at 0.25 mg once weekly for weeks 1 to 4. The purpose is to let treatment begin at a lower dose before increasing gradually.

The next stages are:

• 0.5 mg, used once weekly during the next four-week block.
• 1 mg, used once weekly during the following four-week block.
• 1.7 mg, used once weekly during the subsequent four-week block.
• 2.4 mg, the standard maintenance dose, used once weekly thereafter.

The exact timing of a dose increase should follow your prescribed plan. If side effects or other clinical considerations affect escalation, your clinician may advise a different approach rather than asking you to alter the pen yourself.

The key point is that one pen normally corresponds to one four-week dosing block. You can't make a pen last longer safely by taking partial doses, spacing injections beyond the prescribed schedule or using visible leftover liquid after the fourth injection.

Why weekly consistency matters

A weekly regimen gives you a predictable injection day and a clear point at which to arrange the next pen. It also reflects how the standard 2.4 mg maintenance approach was evaluated in the STEP 1 evidence base, rather than being a schedule invented for convenience.

Use a calendar, phone reminder or treatment app to record the injection date. If your clinician changes the dose, start a new calculation from the date of that prescribed change. The pen strength and the weekly schedule must match.

A pen's four-dose format doesn't mean every person will move through titration at the same speed. Some patients may need clinical advice before increasing, while others may remain on a stage for longer. The important distinction is between how long the pen delivers its labelled doses and how long your overall treatment plan remains at a particular strength.

How Long a Wegovy Pen Lasts After Opening and in Storage

A Wegovy pen can “last” in three different senses: it can contain a set number of prescribed doses, remain usable for a limited period after first use, or stay stored unopened until its printed expiry date. Keeping these meanings separate prevents a storage limit being mistaken for permission to take extra doses.

A standard pen provides four weekly doses. After the first injection, UK product information allows the in-use pen to be kept for six weeks, provided the stated temperature and storage conditions are followed. Six weeks is a stability limit, not an instruction to stretch treatment or create additional doses. Once the four prescribed injections have been given, dispose of the pen according to local guidance, even if the six-week period has not ended.

Opened versus unopened pens

An unopened pen kept correctly in a refrigerator at 2°C to 8°C can be used until the expiry date on its label. It does not begin a four-week or six-week countdown while it remains unopened and refrigerated. For more detail, see guidance on whether Wegovy needs to be refrigerated.

If the pen is kept outside the fridge at a temperature not exceeding 30°C, the permitted storage period is 42 days, or six weeks. The UK storage guidance for Wegovy pens explains the difference between refrigerated storage and time-limited storage below 30°C.

What counts as first use

The first injection starts the in-use period. Record that date in your medicines record or calendar, much like marking the start of a timed window. This avoids having to estimate later when the six weeks began.

Protect the pen from light and do not freeze it. If it has been exposed to unsuitable conditions, speak to a pharmacist or prescriber before using it. The appearance of the solution alone cannot confirm that storage has remained safe.

Storage rule: Four weeks describes the number of standard doses. Six weeks describes the permitted in-use shelf life. They answer different questions.

A missed injection does not automatically restart the six-week clock. Returning an opened pen to the fridge also does not extend an in-use period that has already started. Ask the prescriber managing your Wegovy treatment how to handle a missed dose, rather than changing the schedule yourself.

Why the New 7.2 mg Dose Changes How Long a Pen Lasts

The familiar “one pen lasts four weeks” answer applies most neatly to standard UK dosing. The picture changed on 6 January 2026, when the MHRA approved a maximum Wegovy dose of 7.2 mg once weekly for adults with obesity.

This higher dose is not delivered as one 7.2 mg injection from a single standard pen. Instead, one weekly 7.2 mg dose consists of three 2.4 mg injections. That means the number of pen uses required each week increases, so pen duration no longer maps one-to-one to a four-week calendar block.

Who this applies to

The higher-dose pathway is relevant only to patients whose prescriber has specifically approved escalation. UK guidance and patient-leaflet information state that, after at least four weeks on 2.4 mg, some patients may step up to 7.2 mg once weekly. The package leaflet lists 7.2 mg as the maximum weekly dose.

That doesn't change the standard schedule for someone starting treatment. New patients still begin with the prescribed lower-strength escalation plan, and people remaining on 2.4 mg maintenance still use the ordinary four-dose weekly pattern.

Why the calculation changes

At 2.4 mg maintenance, each weekly injection uses one 2.4 mg dose. At 7.2 mg, each weekly treatment uses three 2.4 mg injections. The pen is therefore consumed according to the total number of injections required for the weekly dose, rather than one injection per week.

This is a good example of why “how long does a Wegovy pen last” needs a regimen attached to it. The device format, prescribed strength and number of injections per weekly dose all matter. Patients shouldn't use the 7.2 mg pattern to estimate standard treatment, and they shouldn't move to that dose without clinical direction.

If your prescription changes, ask the prescriber or dispensing pharmacy how many pens are needed for the next treatment period. The answer may differ from your previous supply pattern because the dosing pathway has changed.

Practical Tips for Calculating Doses Handling Travel and Disposal

You are preparing the fourth injection, but the next pen has not arrived, or the pen has spent part of the journey outside the fridge. A short record makes the answer clearer because “last” can mean doses remaining, time since first use, or the storage limit for an unopened pen.

Write down the first injection date, your weekly injection day, the prescribed strength and the planned date of the fourth dose. This record counts treatment doses and helps you monitor the in-use period.

A reusable monthly check

• Record the first-use date: This begins the six-week in-use period.
• Mark four injection dates: These are the standard pen's labelled doses.
• Check the next strength: During titration, confirm that the next pen matches the dose prescribed by your clinician.
• Review supply early: A pen normally covers four weeks of standard treatment, but the next strength may not be available at your usual pharmacy.
• Check storage conditions: An unopened refrigerated pen follows its printed expiry date. A pen kept outside the fridge below 30°C follows the permitted six-week limit.

A supply gap can affect treatment planning even when the current pen has been used correctly. UK availability reporting says the severe shortage seen during 2022 to 2024 had largely eased in 2026, although individual strengths could still be difficult to find at some pharmacies, as described in the UK medicines availability update. NHS specialist weight-management services and private providers may use different access routes, so ask your prescriber or pharmacy what to do if the next strength is delayed.

Travel and missed injections

During travel, keep the pen within the recommended temperature conditions and protect it from freezing, heat and direct light. Accessible hand luggage can make temperature control and security checks easier. Ask your pharmacist or prescriber about any journey that creates uncertainty about storage, particularly if refrigeration will not be available.

If an injection is missed, do not take extra medicine or alter the schedule without advice. Contact your prescriber if the missed dose affects planned titration or leaves you unsure which strength should be used next.

Disposal

After the fourth standard dose, use the disposal route advised by your pharmacy or local medicines service. Needles and sharps must go into an appropriate sharps-disposal route, not ordinary household waste. If a pen has expired, been frozen or still contains medicine, ask a pharmacist how to return it safely.

For people seeking supervised support with prescription assessment and ongoing weight-management care, Trim's medically supervised weight-management service is one private option to consider. Choose any service only after checking that it suits your clinical needs and prescribed treatment plan.

Key Takeaways for Planning Your Next Wegovy Pen

For standard UK Wegovy treatment, the calculation is straightforward: one pen delivers four once-weekly doses, so it normally covers four weeks. That's the dosing answer, not the storage answer.

Keep these distinctions separate:

• Four doses: The standard pen's treatment capacity.
• Six weeks in use: The permitted period after first use, even if solution remains.
• Printed expiry date: The limit for an unopened pen stored refrigerated at 2°C to 8°C.
• 42 days below 30°C: The permitted storage period when the pen is kept outside the fridge within that temperature limit.
• 7.2 mg pathway: A specific higher-dose regimen using three 2.4 mg injections for one weekly dose, so it needs a different supply calculation.

Before starting a pen, check its strength, expiry date and storage history. Once you use it, record the opening date and mark the four planned injection days. Arrange the next prescription or supply before the final dose, especially during titration when the next pen may need a different strength.

Don't split doses, use visible leftovers or change the injection schedule to make a pen last longer. If you miss a dose, experience a storage problem or move towards the 7.2 mg pathway, contact your prescriber or pharmacist for individual advice.

Understanding the three meanings of “last” gives you a safer, calmer way to plan treatment. Count the doses, track the opening date and match every calculation to the regimen you've been prescribed.

If you're planning your next Wegovy pen or need support coordinating treatment, visit Trim to learn about its UK-based clinical assessment, prescription support and ongoing weight-management guidance. Use the service to discuss suitability, dose planning and continuity with registered clinicians rather than changing your treatment schedule alone.