How to tell when your Wegovy pen is empty

Step 1: understand what the pen shows you before you start

The Wegovy pre-filled pen is designed with a transparent dose window on the side of the barrel. Inside that window sits a yellow plunger rod. Before the very first injection, the plunger sits at the top of the window; you will see the yellow colour clearly. Each time you use the pen correctly, the plunger moves a little further down. After four injections (one per week over a month) it reaches the bottom of the window and becomes flush with, or moves beyond, the lower edge of the dose indicator markings.

Before each injection it is worth spending a few seconds looking at the window in good light. Some people find this easier sitting down by a window rather than standing in a bathroom. The yellow should be obvious. If you are squinting to find it, the pen may already be on its last dose or empty. For a fuller visual guide to what each stage looks like, this page describes the empty pen appearance in detail.

One practical note: if your pen arrived mid-month (perhaps because you ordered just before a bank holiday or a long weekend) your first injection date may not fall neatly on a Monday. The pen does not know the calendar; what matters is one injection every seven days, on the same day each week as agreed with your prescriber.

Step 2: check the pen during and immediately after each injection

Knowing the pen is empty at the end of the month is straightforward. Knowing that a single injection went in properly is a different question, and one that catches many people out. The pen delivers its dose when you hold it firmly against the skin, press the purple injection button, and keep it in place until the click sounds and the button has fully depressed. The NHS patient information for semaglutide confirms that the dose window indicator will show movement after a successful injection, which is the most reliable visual cue that medicine was actually delivered.

If you are unsure whether a particular injection went in, our guide on confirming each Wegovy injection covers the specific checks in more detail. There is also the question of what to do if you missed a dose or suspect an injection failed — both situations call for a conversation with your prescriber rather than a repeat dose on the same day. The NHS semaglutide medicines page outlines what to do if a dose is missed.

For day-to-day reassurance about technique, confirming the injection went in correctly is a question our prescribers hear regularly. You are not alone in wanting to be certain.

Step 3: recognise when the pen is genuinely empty and dispose of it safely

After the fourth injection from a pen, two things happen. First, the plunger in the dose window will have travelled to its endpoint, there is no yellow indicator left visible. Second, the pen's mechanism locks: the button will not travel down when you press it, and the needle cap cannot be re-engaged for another injection. These two signals together confirm the pen is empty. Do not attempt to use it again.

If you are still not certain what you are looking at, this step-by-step visual walkthrough of an empty pen may help. For a quick overview of the empty-pen state, the empty Wegovy pen page has a concise summary.

Once confirmed empty, the pen (needle included) should go straight into a sharps disposal container. Household bins are not appropriate for used medicine pens; a 1-litre sharps container is a straightforward solution for home disposal. Your local council website will tell you how to arrange collection or a drop-off point.

What to do when you need your next pen

An empty pen means it is time to arrange your next supply. Wegovy is a prescription-only medicine, so every repeat requires a clinical review, not simply a repeat click in a basket. At nume, a GPhC-registered prescriber personally reviews each repeat order before anything is dispensed. Place the order before noon on a working day and, once clinically approved, the pen is dispatched the same day and delivered free by DPD the next working day.

If you have questions about your treatment, dose, or what happens at each stage, the Wegovy treatment overview covers the full picture. You can also explore all available weight-loss treatments if your circumstances have changed since you started. And if you are curious how semaglutide compares to other injectable options, this page on weight-loss injections sets out the differences plainly. For general questions our FAQs are a useful first stop before reaching out directly. When you are ready to continue treatment, speak to our prescribers and we will take it from there.