Neurotoxin injection is the most commonly performed nonsurgical cosmetic procedure in the United States. The popularity of this procedure is due to effectiveness, relatively low cost, risk and recovery time. There are several different brands of neurotoxins available in the US based on the botulinum toxin, with the two most popular brands being Botox and Dysport. When injected within or near a muscle, the toxin will block signals from the nerves to that muscle, thereby preventing the muscle from contracting. The muscle becomes weakened and may temporarily be unable to contract. This prevents the formation of or worsening of skin folds on the face that are created and reinforced by muscles contracting or animation.
The most common injection areas are where muscles of animation contribute to prominent skin wrinkles. This also coincides with the treatment areas where the FDA has approved the use of these medications (on-label uses). These areas include the glabella (area between eyebrows and just above the nose), the forehead, and the outside area of the eyes (the crow's feet). Neurotoxins can also be used in other locations around the face and neck to limit skin wrinkles due to muscle contraction, but are considered "off label" use by the FDA.
Neurotoxins used today are not able to erase deep, fixed wrinkles of the skin. If the wrinkles in the skin are made worse or more prominent when the underlying muscle contracts, then weakening the muscle should improve the overall appearance of the wrinkle (but will still not erase the resting line). With chronic use, these deep lines may ultimately soften and become less prominent but this is not guaranteed. The best solution to fill these deeper fixed or static grooves is with a filler. Furthermore, Botox does not permanently prevent muscle contraction. The nerves will eventually be able to stimulate the muscle to contract. This is typically within 3-5 months, and will vary based on several factors.
