Botulinum toxin exerts its effect by cleaving key proteins required for nerve activation. First, the toxin binds specifically to nerves which use the neurotransmitter acetylcholine. Once bound to the nerve terminal, the neuron takes up the toxin into a vesicle. As the vesicle moves farther into the cell, it acidifies, activating a portion of the toxin which triggers it to push across the vesicle membrane and into the cell cytoplasm.[1] Once inside the cytoplasm, the toxin cleaves SNARE proteins preventing the cell from releasing vesicles of neurotransmitter. This stops nerve signaling, leading to paralysis.[1]
Results will be evident within three to 10 days. Photographs may be taken before the procedure so that patients can check their results themselves rather than relying on their memory. It is surprising to see how many people do not recall how they looked before the procedure and are amazed at the difference when shown a picture. Prior to having the procedure done, the patient should realize that Botox does not actually erase lines but relaxes them. What this means is that deeper lines will become somewhat less deep and superficial lines will nearly disappear. This can be likened to the act of steaming a garment's wrinkles rather than ironing them.

Treatment with BOTOX and other botulinum toxin products can result in swallowing or breathing difficulties. Patients with preexisting swallowing or breathing difficulties may be more susceptible to these complications. In most cases, this is a conseq uence of weakening of muscles in the area of injection that are involved in breathing or oropharyngeal muscles that control swallowing or breathing [see Spread Of Toxin Effect].
There are eight types of botulinum toxin, named type A–H. Types A and B are capable of causing disease in humans, and are also used commercially and medically.[3] Types C–G are less common; types E and F can cause disease in humans, while the other types cause disease in other animals.[4] Type H is considered the deadliest substance in the world – an injection of only 2 ng can cause death to an adult.[5] Botulinum toxin types A and B are used in medicine to treat various muscle spasms and diseases characterized by overactive muscle. Commercial forms are marketed under the brand names Botox and Dysport, among others.[6][7]
Who is injecting your Botox? Injecting Botox is deceptively easy. After all, it looks like the nurse or physician just takes a little fluid and squirts into facial muscles, and Walla ! Perfection! The answer is No! You should choose a specialist with years of experience and the ability to assess your facial features to create the best treatment plan possible. Because when Botox is injected in the wrong place it can produce unwanted side-effects that you might find disturbing. For instance if the injector “chases” a wrinkle across your forehead and it happens to be too close to your central eyebrow then the Botox or Dysport can drift downward inhibiting a muscle that lifts your eyelid resulting in a drooped upper eyelid. I know you don’t want that! Or if the practitioner injects only your “11” frown lines between your brows and does not inject other areas of your brow to balance out the effect then you may get a “boomerang”brow – a “Spock”-like overarched  brow that looks hideous. So like everything else experience counts but more experience usually translates into a more expensive treatment sessions. However, avoiding complications can save you money and aggravation in the long run.
Baby Botox can also be used as an upkeep strategy. "I really think of it as small maintenance doses of Botox over time instead of standard doses given at three- to six-month intervals," says Smith. "The other term that describes this well is 'tweakment' — subtle changes done over a longer period of time using lower doses of product at each treatment."

It is not known whether BOTOX® is safe or effective to treat increased stiffness in upper limb muscles other than those in the elbow, wrist, fingers, and thumb, or in lower limb muscles other than those in the ankle and toes. BOTOX® has not been shown to help people perform task-specific functions with upper limbs or increase movement in joints that are permanently fixed in position by stiff muscles. BOTOX® is not meant to replace existing physical therapy or other rehabilitation that may have been prescribed.