Can Wegovy be injected intravenously or intramuscularly?

No — Wegovy is for subcutaneous use only. Do not inject into a vein or muscle. Choose the abdomen, thigh, or upper arm, and follow the pen’s instructions to ensure the medicine enters the fatty layer just beneath the skin.

Why the injection route matters

Wegovy (semaglutide) is formulated specifically for subcutaneous delivery, meaning it’s designed to release slowly through fatty tissue under the skin. NICE TA875, MHRA guidance, and NHS England’s weight-management materials all emphasise that the route of injection is critical to how the medicine works. Injecting it too deeply or into a vein changes how semaglutide is absorbed, leading to potential nausea, vomiting, dizziness, or low blood sugar. Because semaglutide has a long half-life (around seven days), this disruption can last several days. Correct subcutaneous use ensures steady absorption and stable appetite and glucose effects — the same method tested in all STEP and SELECT clinical trials that informed UK approval.

How to find the right injection layer

The subcutaneous layer lies between the skin and muscle, made mostly of soft fat with few blood vessels. Injecting here allows the medicine to diffuse gradually into the bloodstream. NHS training resources recommend holding the pen at 90° and inserting the needle straight into relaxed skin. For those with less body fat, pinching the area can lift the layer slightly to avoid the muscle below. The needle should not feel painful; a mild pressure or pinch is normal. Keeping the pen pressed flat for the full count (until the window indicator stops moving) ensures the dose is fully delivered.

Why muscles and veins are unsafe

Injecting into muscle or vein bypasses the slow-release mechanism that gives Wegovy its weekly convenience. Muscles are dense and highly vascular, which causes rapid, uneven absorption and may trigger nausea or stronger side effects. In veins, the medicine enters circulation immediately, leading to unpredictable peaks in concentration. MHRA safety notes warn that incorrect injection depth increases risks of local bleeding, swelling, and infection. Because semaglutide is not licensed for intravenous or intramuscular routes, there is no clinical evidence supporting safety through those methods. All UK and international studies, including STEP-1 and STEP-5, used subcutaneous injection exclusively.

Choosing, rotating, and protecting injection sites

Approved sites include the abdomen, upper thigh, and outer upper arm. Rotating between them weekly helps prevent skin irritation and lumps (lipohypertrophy). The abdomen usually provides the smoothest absorption because it’s less involved in everyday movement. NHS practice suggests dividing the abdomen into quadrants and moving clockwise each week to avoid overlap. For active people, injections should avoid recently exercised muscles; for example, runners may prefer the upper arm, while weight-lifters often use the abdomen. Keep the needle capped until use, clean the area gently, and inject only into normal-looking skin — not scars, bruises, or moles.

Technique and aftercare

A new needle must be used each time to avoid dull tips, contamination, or blocked flow. Inject at a steady pace and hold the pen in place for a few seconds after the indicator finishes. Lightly press (don’t rub) the site for 10–20 seconds to limit small bruises. NHS and MHRA guidance confirm that mild redness or itching may occur but usually fades within a day. If a spot becomes sore or swollen, rotate to a different area and mention it at your next review. Pens should be stored in the fridge before first use, then below 30 °C once opened.

What to do if you inject too deeply

If you suspect you’ve injected into muscle — for instance, if there’s sudden sharp pain or visible bruising — don’t re-dose. The medicine may still absorb, though faster than intended. Monitor for nausea, dizziness, or a racing heartbeat, and contact your clinic or NHS 111 for advice. Do not attempt to “replace” the dose. During your next visit, a nurse can review your technique or suggest shorter needles. NHS services regularly provide refresher sessions, especially for people who self-inject long-term or have changes in body weight.

Clinical guidance on training and safety

NICE TA875 and NHS England’s commissioning framework both identify self-injection training as part of treatment initiation. Before prescribing Wegovy, services confirm that the person can handle the pen confidently and understands safe storage and disposal. MHRA guidance adds that correct technique prevents up to 90 % of reported injection-related issues. Proper subcutaneous use was one of the main safety assurances during regulatory approval. These standards are also reflected in Scottish and Welsh frameworks (SMC and AWTTC), which align with NICE recommendations.

Additional technical background

Subcutaneous semaglutide uses a formulation that binds to albumin, a natural protein in the blood, creating a depot effect that allows once-weekly dosing. This pharmacological design depends entirely on gradual absorption from fatty tissue. Direct bloodstream injection bypasses this process, leading to erratic blood levels and shorter duration. Clinical pharmacokinetic studies published in The Lancet Diabetes & Endocrinology confirm that consistent subcutaneous delivery maintains steady plasma concentrations and minimises side-effect spikes. This is why clinicians focus heavily on technique — it preserves both safety and efficacy.

The essential point

Wegovy must always be injected into the fatty layer under the skin — never into a vein or muscle. Subcutaneous use delivers the slow, predictable release needed for steady appetite control and glucose balance. Correct site rotation, calm injection technique, and proper storage all support safe, comfortable treatment. NICE, MHRA, and NHS guidance are unanimous: precision with route and technique is not a small detail but the foundation of Wegovy’s effectiveness.