Wegovy Pen Leaked or Did Not Fully Inject: What the UK Leaflets Say

Why a failed Wegovy injection raises a real question

Wegovy (semaglutide) is a prescription-only weekly injection licensed in the UK for weight management and for some other indications set out in its Summary of Product Characteristics (SmPC), the regulator-approved prescribing document.^[2] Because it is given once a week, one injection is a whole week’s dose. Treatment starts at 0.25 mg and is increased every four weeks to a 2.4 mg maintenance dose, and a higher 7.2 mg dose can be used in some adults with obesity.^[2] A pen that clicks but leaves liquid on the skin therefore raises an understandable question: did the dose go in, and what happens next?

This article reports what the current UK leaflets and SmPC say. It cannot judge what happened with a particular pen, and it is not individual advice. The NHS warns that some websites sell fake weight-loss medicines,^[4] and the Yellow Card scheme accepts reports of suspected fake medicines.^[5]

Which Wegovy pen are you holding?

Search phrases such as ‘yellow bar stopped halfway’ and ‘dose counter’ describe two different devices. The checks that apply depend on which one is in your hand.

FlexTouch multi-dose pen

The FlexTouch pen is a dial-a-dose pen. Each pen holds four doses of one strength (0.25 mg, 0.5 mg, 1 mg, 1.7 mg or 2.4 mg), and the pack contains four disposable needles that screw onto the pen.^[1] You turn a dose selector, press a dose button and read a dose counter. The FlexTouch leaflet does not mention a yellow bar.

Single-dose 7.2 mg pen

The 7.2 mg pen is single-use and holds one pre-set dose. It has a needle cover that hides a built-in needle and an automatic dosing mechanism that starts when the cover is pressed against the skin. A yellow bar appears in the pen window during the injection.^[3] The SmPC says the 7.2 mg dose is given either as one 7.2 mg injection or as three 2.4 mg injections, depending on the device.^[2]

How to tell whether the full dose went in

FlexTouch pen: the dose counter is the test

The leaflet’s instructions for the injection step are specific:

1. Insert the needle into the skin and keep the dose counter in view. Covering it with your fingers could interrupt the injection.^[1]
2. Press and hold down the dose button until the dose counter shows -0-.^[1]
3. With the needle still in the skin, count slowly to 6.^[1]
4. Only then remove the needle from the skin.^[1]

The leaflet says you may hear or feel a click when the counter returns to -0-.^[1] Its criterion for a finished injection is the counter reaching -0- followed by the slow count, not the sound alone. A click on its own therefore does not confirm that the dose was delivered.

If the needle is removed too early, the leaflet states that a stream of Wegovy may come from the needle tip and the full dose will not be delivered.^[1] It also says a drop may be visible at the needle tip after injecting, which is normal and does not affect the dose.^[1] The leaflet contrasts a drop with a stream but gives no volume for either, so it cannot tell you how much medicine was lost.

Single-dose pen: the yellow bar is the test

For the 7.2 mg pen, the leaflet instructs users to press the pen firmly against the skin until the yellow bar has stopped moving. The injection takes about 5 to 10 seconds. The first click means the injection has started, and after the second click the pen should be held in place for a few seconds until the bar stops.^[3] If the bar does not start moving, the leaflet says to press the pen more firmly against the skin.^[3]

The same leaflet warns that lifting the pen before the yellow bar stops lets the automatic dosing continue, but the full dose may not be received, and that an injection cannot be paused and restarted later.^[3]

Situation by situation: what the leaflets say

The table sets out each situation the leaflets address. Where a situation is not listed, the documents reviewed are silent.

Why a pen can click but deliver nothing

Two explanations are documented for the FlexTouch pen. First, the needle has two caps, and the leaflet says that if both are not removed you will not inject any Wegovy.^[1] Second, a blocked or damaged needle: if -0- does not appear after you press the dose button continuously, the leaflet says the needle may be blocked or damaged and that you have not received any Wegovy, even though the counter has moved from the dose you set.^[1]

The leaflet links blocked needles to reuse and to leaving the needle attached. It says needles are single-use, that reuse can lead to blocked needles, contamination, infection and inaccurate dosing, and that the needle should be removed immediately after each injection with the pen stored without it.^[1] The SmPC gives similar reasoning, saying that storing the pen without a needle may prevent blocked needles, contamination, infection, leakage of solution and inaccurate dosing.^[2] The leaflet also instructs users not to use a bent or damaged needle.^[1] The documents do not explain why a needle might bend, so no cause can be assigned.

Should you inject again? What the documents say and do not say

This is the question that matters most, and the official documents answer only part of it.

One scenario has a stated route. When a FlexTouch needle is blocked or damaged and the counter did not return to -0-, the leaflet says no Wegovy was received and directs the user to change the needle and set the dose again.^[1]

Other scenarios have no stated route. If liquid escaped after the needle came out early, or the single-dose pen was lifted before the yellow bar finished, the leaflets say the full dose may not have been delivered, but they do not say how to judge the amount received or whether to repeat the injection.^[1][3] No source reviewed measures how much medicine a leak removes, and a spill on the skin cannot be converted into a fraction of a dose.

Three other rules exist for different situations, and they should not be stretched to cover a partial dose:

• Forgotten dose: if it is 5 days or less since the dose was due, inject as soon as you remember; if more than 5 days have passed, skip it. A double dose should not be taken to make up for a forgotten one.^[1][2][4]
• Using more than prescribed: the leaflet says to talk to your doctor straight away,^[1] and the NHS advises contacting 111 if you have had more semaglutide than the packet, leaflet or prescription says.^[4] The SmPC notes that overdose may cause gastrointestinal effects that could lead to dehydration.^[2]
• Changing the weekly injection day: allowed if at least 3 days have passed since the last injection.^[1]

Because the pen type, the strength and the amount lost all vary, whether to repeat an injection is a decision for your prescriber, a pharmacist, or the manufacturer’s medical information service, whose contact details are listed on the emc entry.^[1]

Reducing the chance of a repeat: what the leaflets advise

• Check the pen label for the correct name and dose, and do not use the pen if the medicine looks cloudy or coloured.^[1][3]
• FlexTouch: remove both needle caps, use a new needle for every injection, push it straight onto the pen and turn until tight.^[1]
• FlexTouch: keep the dose counter in view, hold the dose button until -0- appears, then count slowly to 6 before removing the needle.^[1]
• FlexTouch: remove and dispose of the needle immediately after injecting, and store the pen without a needle attached with the cap on.^[1][2]
• Single-dose pen: pull the cap straight off, keep it on until you are ready to inject, press firmly, and hold until the yellow bar stops.^[3]
• Handle the pen with care: the leaflets say not to drop it, knock it, expose it to liquid, or wash or soak it. If needed, clean a FlexTouch pen with a mild detergent on a moistened cloth.^[1][3]
• Store unused pens in a refrigerator and do not use a pen that has been frozen. The leaflets give separate in-use storage limits for the FlexTouch and single-dose pens.^[1][3]
• People with poor eyesight who cannot follow the instructions should not use the pen without help from a trained person.^[1][3]

Reporting a faulty pen

The Yellow Card scheme accepts reports of medicines that do not work properly, are of poor quality or are suspected to be fake, and of faulty medical devices. Anyone can report a problem, although the scheme cannot give medical advice.^[5] The SmPC asks for the product name and batch number to be recorded for traceability.^[2] Having those details to hand will help any report be specific.

Frequently asked questions

Editorial summary

The documents establish how a completed injection looks for each pen. A small drop at the FlexTouch needle tip is normal; a stream of liquid after early removal, a counter that does not reach -0-, or a single-dose pen lifted before the yellow bar stops all point to incomplete delivery. One scenario, a blocked or damaged FlexTouch needle, has a stated route: change the needle and set the dose again.

What remains uncertain is more important to readers. No source quantifies how much medicine a leak removes, no rule covers repeating a partly delivered dose, and the documents do not explain why a particular needle failed. The practical significance is to use the pen-specific completion checks and ask a healthcare professional before improvising a second injection.