How Wrinkle Injections Actually Work: The Science Behind the Results

Wrinkle injections are one of the most performed non-surgical aesthetic treatments in the world—and one of the most misunderstood. Many people walk into a clinic knowing only that it ‘relaxes’ the muscles. But what does that actually mean, and why does it produce the results it does?

Understanding the mechanism behind the treatment helps you set realistic expectations, make sense of your results, and have more meaningful conversations with your doctor.

What Wrinkle Injections Are

Wrinkle injections use a highly purified protein derived from a naturally occurring bacterium. In its pharmaceutical form, this protein is rigorously processed and standardised—it bears almost no resemblance to its raw source, in the same way that pharmaceutical-grade penicillin bears no resemblance to the mould it comes from.

The Neuroscience: What Happens at the Injection Site

Every voluntary muscle movement starts with an electrical signal travelling down a motor nerve. When that signal reaches the nerve ending, it triggers the release of a chemical messenger called acetylcholine into the gap between the nerve and the muscle fibre—the neuromuscular junction. Acetylcholine binds to the muscle and causes it to contract. This is the mechanism behind every smile, frown, squint, and raised brow.

Wrinkle injections block this process. The active protein binds to the nerve terminal and prevents acetylcholine from being released. Without it, the muscle cannot receive the signal to contract—producing a localised, temporary reduction in muscle activity. This is why the treatment is described as neuromodulation: it adjusts neural signalling rather than physically altering the muscle or the skin.

Why Relaxed Muscles Mean Fewer Wrinkles

Wrinkles come in two main types: dynamic and static.

Dynamic wrinkles appear only during expression—the lines that form when you squint, smile, or frown. Static wrinkles are present even at rest, formed when years of repeated skin folding leaves a permanent crease, compounded by the natural decline in collagen and elastin that comes with age.

Wrinkle injections are most effective against dynamic wrinkles, because they address the root cause: repeated muscle contraction. When the muscle is temporarily relaxed, the overlying skin is no longer being folded with every expression. With early enough intervention, this can also prevent dynamic wrinkles from progressing into static ones. For already-established static lines, the treatment can soften their appearance by reducing the ongoing movement that deepens them further.

Why Results Are Temporary—and When They Wear Off

The effects typically last between three to six months. Over time, the nerve terminal sprouts new connections and gradually restores normal acetylcholine release, returning muscle function and with it, the capacity for movement that causes dynamic wrinkles.

Several factors influence how long results last:

•       Metabolism—faster metabolic rates tend to shorten the duration of results

•       Muscle mass and activity—larger, more frequently used muscles may require higher doses or more frequent treatments

•       Lifestyle—high-intensity exercise and excessive sun exposure can influence how quickly effects wear off

•       Treatment history—consistent treatments over time often lead to longer-lasting results, as targeted muscles gradually become less active from reduced use

With repeated, well-timed treatments, muscles can become progressively less hyperactive—which is why consistent patients often need less product over time to achieve the same result.

Common Treatment Areas

•       Forehead lines—caused by the frontalis muscle; careful dosing is required to avoid brow heaviness

•       Frown lines—involve the corrugator supercilii and procerus muscles; one of the most common indications with highly noticeable results

•       Crow’s feet—caused by the orbicularis oculi muscle around the eye; respond very well to treatment

•       Jaw slimming—reducing masseter muscle activity leads to a slimmer facial contour over time, particularly beneficial for those who clench or grind their teeth

•       Gummy smile—a small amount placed at the upper lip reduces how much it elevates when smiling

•       Neck bands—relaxing the platysma muscle reduces prominent vertical bands and improves neck contour

•       Hyperhidrosis—an effective, well-evidenced treatment for excessive sweating in the underarms, hands, and feet

Thinking about wrinkle injections?              

Every face is different, and the right approach depends on your anatomy, skin condition, and aesthetic goals. Book a consultation with Singapore Aesthetic Centre to find out what treatment approach is right for you.