These are both Botulinum Toxin type A. The muscles that cause frowning are stimulated by nerve endings. This happens at the neuromuscular junction where acetylcholine, one of the neurotransmitters is released. Acetylcholine stimulates the muscle and causes contraction. Botulinum toxins blocks the release of acetylcholine and prevents muscle contraction. This happens only within a half an inch area where the injection is done with Botox and slightly larger area with Dysport.  Only a specific area of a muscle is relaxed. This effect has been used for many years to prevent abnormal muscle contractions, like in torticollis. The cosmetic benefit is however what has made Botox a block buster drug. Patients always tell me that they are worried about injecting a toxin in the body. My answer is that all drugs and even some foods are toxins. For example, one can die of an over dose of Tylenol, an over the counter drug. It’s all a question of dosage. In minimal doses, toxins can be perfectly safe and produce desirable effects. Indeed the doses of Botox used for cosmetic effects are very safe.

 

These products are FDA approved for the frown areas, but they are routinely used off label to reduce crows feet, forehead lines, platisma bands under the chin and other muscles like the ones that depress the corner of the mouth (depressor anguli oris). With knowledge of the anatomy of the facial musculature one can produce a brow lift by weakening the depressors of the brows and allow the forehead (frontalis) muscle tone to pull the brow up. This effect can be used to shape the brow as well.

 

Recently the FDA approved the use of Botox to relieve migraine headaches. I was instructed by Dr. Bahman Guyuran, who first discovered this effect. I have been using it ever since with success in patients with migraines. The theory is that the constant frown muscle contractions cause nerve irritation and trigger the migraine.