Botulinum toxin injections are among the most commonly used aesthetic treatments to reduce wrinkles. Although very widespread, the question many people still ask is : how does botulinum toxin actually work ? Indeed, not everyone knows its mechanism of action at the cellular and muscular level, which allows for visible and lasting results.
In this article, we will explain in detail how botulinum toxin acts on muscles and neurons, and how this translates into a reduction of wrinkles and muscle contractions.
Botulinum toxin is a neurotoxin produced by the bacterium Clostridium botulinum. There are different types of this toxin, but the form most commonly used for medical and aesthetic purposes is type A.
Used for many years in medicine, this molecule is recognized for its effectiveness and safety profile when injected by a specialist. In Geneva, it is one of the most popular treatments in aesthetic-oriented medicine.
Botulinum toxin is one of the most effective substances known to modulate communication between nerves and muscles. It works by temporarily blocking the transmission of nerve signals.
In practical terms, this means it prevents certain muscles from contracting excessively. This targeted relaxation helps soften some expression lines, prevent the formation of static wrinkles, and give the face a relaxed and naturally rejuvenated appearance — without freezing the features when injected with precision and subtlety.
Its action is reversible and controlled, making it a treatment of choice in aesthetic-oriented medicine in Geneva.
To understand the mechanism of action of botulinum toxin, it is essential to understand how muscles normally contract.
Muscle movements are controlled by the nervous system. When a signal is sent from the brain or spinal cord to move a muscle, it travels along a motor neuron until it reaches the junction between the neuron and the muscle, called the neuromuscular junction.
At this junction, the nerve releases a neurotransmitter called acetylcholine into a small area known as the synaptic cleft (the space between the nerve and the muscle cell).
Acetylcholine binds to specific receptors located on the surface of muscle cells, which triggers their contraction.
Type A botulinum toxin acts directly on this nerve transmission process, thereby blocking the release of acetylcholine and inhibiting muscle contraction.
Inhibition of acetylcholine release : botulinum toxin acts at the level of nerve endings by blocking the release of acetylcholine. It does so by cleaving specific proteins within the vesicles containing acetylcholine, thereby preventing these vesicles from fusing with the membrane of the nerve cell. In other words, the toxin “deactivates” the acetylcholine release mechanism.
Without this neurotransmitter, the muscle is no longer able to receive the signal required for its contraction. The muscle therefore remains relaxed.
Temporary effect on muscles : the effect of botulinum toxin is temporary, as nerve cells eventually generate new endings capable of releasing acetylcholine. This means that the results of the injection generally last between 3 and 6 months, depending on the treated area and the patient’s metabolism.
Precise targeting of muscles : during a botulinum toxin injection, the doctor targets specific muscles to relax only the areas responsible for expression lines. For example, to treat forehead wrinkles or crow’s feet, botulinum toxin is injected into the muscles responsible for repeated contractions in those areas. This makes it possible to achieve smooth skin in the injected area while maintaining a natural facial expression.
Botulinum toxin specifically reduces the activity of the muscles responsible for expression lines. Over time, repeated facial movements lead to the appearance of forehead wrinkles, frown lines between the eyebrows, and crow’s feet around the eyes. These constant muscle contractions eventually mark the skin, even at rest.
By temporarily relaxing these muscles, botulinum toxin gradually softens these expression lines. The skin becomes smoother, the gaze appears more rested, and the features gain softness without ever losing their natural look. When injected with precision, it helps preserve the harmony of the face and achieve a subtle, elegant result perfectly aligned with the refined aesthetics sought in Geneva.
The muscle relaxation induced by botulinum toxin does not appear immediately. After the injection, the product acts directly on the targeted muscle and begins to block the transmission of nerve signals shortly after administration. Although some people notice an improvement within two to three days, the optimal result usually appears around the seventh day.
The effect then lasts for an average period of three to six months, during which the nerve endings gradually regenerate. When muscle activity resumes, expression lines may reappear, which explains the need to maintain the treatment to preserve the result.
It is important to distinguish botulinum toxin from other injectables such as hyaluronic acid, as they do not act in the same way and are used for different indications.
The main role of botulinum toxin is to relax the muscles responsible for certain expression lines, also called dynamic wrinkles. By limiting repeated muscle contractions — in the forehead, frown lines, and crow’s feet — it prevents the appearance of new wrinkles and softens those already visible.
Hyaluronic acid, on the other hand, is a dermal filler. It helps correct static wrinkles, restore lost volume, redefine facial contours, perform facial lifting techniques, and deeply hydrate the skin (Skinboosters). Its action is therefore structural and volumizing, whereas botulinum toxin acts on muscle dynamics.
These two approaches are often complementary : botulinum toxin smooths and prevents, while hyaluronic acid fills and rebalances. Used together in a personalized protocol, they allow for a balanced, natural, and long-lasting result.
Repeated botulinum toxin injections have beneficial long-term effects. Indeed, when muscles are continuously relaxed, wrinkles no longer form as easily, which can slow down the facial aging process in the treated areas. However, it is essential to maintain reasonable intervals (4 to 6 months) between injections to avoid the development of tolerance to the toxin.
Botulinum toxin injections are considered safe when performed by an experienced physician. The most common side effects are minor, such as redness or bruising at the injection site, and they usually disappear after a few days.
Article written by Dr Romano Valeria
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