What if I injected into the wrong site or the dose leaked?

If a little fluid appears on the skin, it’s usually from the needle track rather than a full dose loss. As a rule, don’t inject an extra dose; note what happened and continue with your next scheduled injection. For clear device errors (pen not primed correctly, needle blocked, or you know the dose didn’t deliver), contact your pharmacist or clinic for specific advice before re-dosing. To prevent repeats, ensure the needle is new, the pen is pressed flat against the skin, and you hold it in place for the full time shown in your instructions.

Understanding how injections work

Wegovy pens deliver semaglutide under the skin, usually into the abdomen, thigh, or upper arm. The medicine is then absorbed slowly into the bloodstream over the course of a week, which is why precise technique matters. If a drop of fluid appears after removing the needle, this is normally from the injection track and not evidence that the dose failed. NICE TA875 and NHS instructions emphasise that if you are uncertain, do not inject again, as repeating too soon risks overdosing and unnecessary side effects.

Recognising true device errors

Occasionally, a genuine delivery problem does occur. This could be a blocked needle, a pen that has not been primed correctly, or a situation where the injection button is not fully pressed. In these cases, the medicine may not have entered the skin at all. MHRA-approved product information advises that patients should not try to “guess” but should seek advice before re-dosing. Community pharmacists, GPs, or weight management clinics can confirm whether another injection is required, and in some cases a replacement pen may be supplied. Keeping the faulty device for inspection helps staff understand the problem and report it if needed.

How to reduce the risk of leaks

Most small leaks are preventable with good injection habits. Always use a new needle for each injection, attach it firmly, and press the pen flat against the skin. Holding the pen steady for the full time shown in your leaflet — usually around ten seconds — allows the full dose to leave the cartridge and settle under the skin. Removing it too quickly is one of the most common causes of seeing a drop of liquid. NHS patient information also recommends rotating injection sites to avoid irritation and to ensure even absorption of the medicine.

Why not to repeat the dose

Clinical trials such as STEP-1 and STEP-5 only tested semaglutide on the basis of single, once-weekly injections. Doubling up or injecting again outside this plan was not part of the research. NICE TA875 bases its recommendations on those trials, which demonstrated an average 15% weight loss over 68 weeks and sustained benefits at two years when the weekly routine was followed consistently. Re-injecting after a small leak introduces unpredictable drug levels and increases the risk of nausea, vomiting, and diarrhoea. NHS guidance therefore stresses that continuing with the next scheduled dose is the safer course in almost all situations.

When to seek professional advice

If you are certain that no medicine entered the skin — for example, the needle was blocked, the pen misfired, or the button was not pressed fully — you should contact your pharmacist, GP, or clinic before taking further action. They can advise whether to take another dose and how to avoid the same problem next time. The MHRA encourages patients to report suspected device failures through the Yellow Card scheme, as this helps track safety and improve design over time. NHS weight management services also reassure patients that no one should feel pressured to solve these problems alone — trained staff are there to support safe and effective use.

Building confidence through practice

Many people describe the first few injections as the most stressful, but confidence usually grows quickly. A nurse demonstration can help at the start, especially for showing how firmly to press the pen and how long to hold it in place. Keeping a short note of what happened if you notice a leak — the injection site, needle used, and how long the pen was held — can be useful for spotting patterns. These details can then be shared with your clinician if problems continue. Over time, injections become routine, and small uncertainties like a drop of liquid are easier to interpret calmly.

Lessons from clinical evidence

The large STEP and SELECT trials, which underpin NICE approval and NHS commissioning, relied on patients taking their injections consistently and without dose duplication. The fact that results were achieved on the once-weekly plan is the reason regulators such as the MHRA insist on sticking to it. Splitting doses or re-injecting after leaks has not been tested, so its safety and benefit are unknown. This is why guidance stresses patience and professional support rather than improvising. Protecting the consistency of dosing is central to making sure real-world results mirror those seen in the research.

The main message

A small drop of liquid after injection is usually harmless and not a sign that the dose failed. True device errors are rare, and the safest response is to seek professional advice rather than injecting again. By using a new needle each time, pressing the pen firmly and flat against the skin, and holding it in place for the recommended time, most problems can be avoided. Staying calm, noting what happened, and continuing with your normal schedule keeps treatment on track and aligned with the evidence base used by NICE, the MHRA, and the NHS.