A Guide to Muscle-Relaxing Injections: How Does it Work?

September 22, 2026

Muscle-relaxing injections help soften expression lines caused by repeated muscle movement. They work by temporarily reducing activity in specific muscles involved in frowning, squinting, or raising the brows. Treatment targets these muscles to soften the appearance of the lines they create.

What Are Muscle-Relaxing Injections and How Do They Work?

How Muscle-Relaxing Injections Reduce Muscle Activity

Muscle-relaxing injections act at the neuromuscular junction, where a nerve ending meets a muscle fibre. Normally, nerve signals trigger the release of acetylcholine, a chemical messenger that tells the muscle to contract. The injected medication temporarily blocks the release of this messenger at the treated site, reducing the strength of muscle contractions. This helps soften the creasing of the overlying skin during facial expressions.

The effect is temporary. As nerve signalling gradually recovers, muscle activity returns and the treatment’s effects wear off.

Dynamic Lines vs Static Lines: Why the Difference Matters

Dynamic lines only appear when a muscle contracts, such as the creases that form when you frown or squint. Static lines are visible even when your face is at rest, usually because the skin has lost some elasticity or because a dynamic line has been repeated so often that it has etched into the resting skin. Muscle-relaxing injections are most effective on dynamic lines and on early static lines that are still largely driven by muscle movement. Deeper static lines and volume loss are better addressed with other treatments, such as dermal filler or skin-quality treatments.

Common Treatment Areas

Frown Lines, Forehead Lines, and Crow's Feet

The upper face is where Muscle-relaxing injections are most commonly used, since the muscles here are small, superficial, and directly responsible for the glabellar frown lines between the brows, horizontal forehead lines, and crow’s feet around the eyes. These areas respond predictably to treatment because the muscles are close to the skin and their movement is easy to assess before and after treatment.

How Dosing Is Tailored to Each Muscle

Dosing is measured in units and varies by muscle size, strength, and the individual’s goals. Men typically need higher doses than women due to greater muscle mass. Larger muscles, such as the masseter used for jaw slimming, require a larger dose as well and are split across several injection points. Your clinician will assess your muscle strength and movement pattern before recommending a dose, rather than applying a fixed amount to everyone.

What to Expect From Onset to Peak Effect

The Typical Timeline After Injection

Muscle-relaxing injections do not work instantly. Most patients begin to notice softening within a few days, with the full effect typically visible by around two weeks. This is why clinicians usually recommend waiting at least two weeks before assessing your result or booking a touch-up.

How Long Results Usually Last

The effect of a standard treatment generally lasts three to six months, after which muscle movement gradually returns to normal as the nerve ending regenerates. Individual duration varies with metabolism, muscle strength, dose, and treatment area, and tends to shorten slightly with very frequent, low-dose repeat treatment.

Who Is a Good Candidate?

Muscle-relaxing injections tend to suit people who are bothered by expression lines caused by repeated muscle movement, want a non-surgical option with minimal downtime, and are looking for a subtle, natural-looking softening rather than a change to their underlying facial structure. This treatment is not suited to volume loss, skin laxity, or pigmentation, and is best assessed alongside your other concerns during a consultation.

Safety Considerations and Contraindications

Common Side Effects and How They're Managed

Muscle-relaxing treatment is generally considered safe when administered by a trained clinician. Temporary bruising, mild swelling, or a slight headache at the injection site are the most commonly reported effects and usually resolve within days. Less common effects, such as brow heaviness or asymmetry, are typically related to injection placement and dosing, which is why precise anatomical assessment matters.

Who Should Avoid Treatment

Muscle-relaxing injections are not suitable for everyone. They are generally avoided in pregnancy and breastfeeding, in patients with certain neuromuscular disorders such as myasthenia gravis, and in those taking medications that affect neuromuscular transmission. A full medical history is taken before treatment to check for these and other contraindications.

How This Fits Into a Broader Anti-Ageing Plan

Combining With Skin Quality Treatments

Because muscle-relaxing injections address muscle movement rather than skin quality, they are often combined with treatments that target hydration, collagen or volume, such as hyaluronic skin boosters or dermal filler, depending on what a patient’s skin actually needs.

Why Muscle Relaxation Alone Isn't a Full Facial Plan

Facial ageing involves more than muscle activity: bone, fat compartments and the skin itself all change over time. Muscle-relaxing injections are one useful tool among several, and work best as part of a plan that also considers these other layers where relevant.

Book Your Consultation at Vidaskin

The right approach to expression lines starts with understanding which muscles are actually driving them, and whether muscle movement, skin quality, or both are contributing to what you see in the mirror.

At VIDASKIN, muscle-relaxing treatment is planned around your individual muscle pattern, facial anatomy, and aesthetic goals, while preserving natural movement.

To learn more or book a consultation, visit us here today.

FAQ Section

Do muscle-relaxing injections hurt?

Most patients describe the injections as a brief pinching or stinging sensation. Fine needles and, where needed, topical numbing help keep discomfort minimal.

How soon will I see results?

Softening usually begins within a few days, with the full effect typically visible around two weeks after treatment.

Will treatment make my face look frozen?

When dosed and placed appropriately, muscle-relaxing injections are intended to soften specific expression lines while preserving natural movement elsewhere in the face. An overly frozen appearance is usually a sign of excessive dosing rather than an inevitable effect of the treatment.

Can this be combined with other treatments?

Yes. Because it addresses muscle movement rather than skin quality or volume, it is commonly combined with hyaluronic skin boosters or dermal filler as part of a broader plan.

Dr Kay Low

Dr. Kay Low is a UK-trained medical doctor with over 7 years of clinical experience across the UK and Singapore, specialising in aesthetic medicine. A graduate of the University of Cambridge, she has worked across multiple medical and surgical disciplines in the UK and Singapore before completing postgraduate training in Family Medicine and advanced training in aesthetic medicine.