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]
It was peculiar advice coming from a shrink, but not without precedent. In 2014, Rosenthal, a clinical professor of psychiatry at Georgetown University School of Medicine, and Dr. Eric Finzi, an assistant professor of psychiatry at George Washington School of Medicine, published a study showing that when people with major depression got Botox, they reported fewer symptoms six weeks later than people who had been given placebo injections. "I'm always on the lookout for things that are unusual and interesting for depression," says Rosenthal, who is widely considered an expert on the condition. "I've found Botox to be helpful, but it's still not mainstream."
It may be the most well known, but Botox is just one type of neurotoxin on the market. Other, next-level neurotoxins are Dysport, FDA-approved in 2009, and Xeomin, FDA-approved in 2011. “They all originate from the same strain of bacteria, therefore they work essentially in the same way,” explains Z. Paul Lorenc, MD, a board certified aesthetic plastic surgeon in Manhattan. “There are some nuanced differences between the three,” he adds. Xeomin is a purified neurotoxin, also called a “naked molecule,” because it doesn’t contain any extra surface proteins, the way Botox and Dysport do. This “pure” neurotoxin migrates deeper into skin, works faster, and poses less risk of an allergic reaction. “Theoretically, decreasing the protein load also lessens the chance of becoming a non-responder, meaning it lessens the chance that the patient will become immune to the neuromodulator being injected,” Dr. Lorenc says. Dysport tends to spread a little more than Botox, so it’s good for areas that would otherwise need multiple injections. It also kicks in faster than the other two, typically showing effects after two to three days opposed to seven to ten days with Botox, and five to six days with Xeomin. Once you try the different neurotoxins, you might decide you like one brand better than the others.

Sunburn alert: The AHA/BHA Exfoliating Cleanser and AHA/BHA Cream in the Lytera® 2.0 Advanced Pigment Correcting System contain an alpha-hydroxy acid (AHA) that may increase the skin’s sensitivity to the sun and particularly the possibility of sunburn. Patients should use a sunscreen, wear protective clothing, and limit sun exposure while using these products (or this system) and for a week following.
As anyone who’s tried Botox for Migraine (or wrinkle reduction) will tell you, your forehead feels heavier after the injections are done, where the nerve endings are in essence frozen. As in ‘Frozen Face.’  Little to no movement, depending on how many units you receive and where they are injected. In my case, my usually expressive face didn’t track with my emotions: no raised eyebrows of surprise or delight or shock.
Remember that the skill of the injector is extremely important when considering Botox injections. Because Botox can have some very obvious and embarrassing side effects like drooping eyelids, blurry vision, and excessive bruising around the injection site, it's important to consult with an experienced injector. Unlike dermal fillers which can be melted away with a follow-up injection of hyaluronidase, there's not much you can do about a bad Botox experience other than wait it out.
I was lucky. My health insurance only required me to try and fail two other less expensive migraine medications, and it didn’t dictate how long I had to try them for before giving up. Other insurers have stricter rules: Aetna, for example, requires patients to try at least three medications for at least two months each. HealthPartners also requires patients to try and fail three medications, such as beta blockers and antidepressants, without specifying for how long. (Requirements may vary by state and policy.) Because these migraine drugs are designed to treat other conditions like high blood pressure and depression, they can have serious side effects like weight gain, fatigue, and difficulty in thinking and speaking clearly.
There has not been a confirmed serious case of spread of toxin effect away from the injection site when BOTOX® has been used at the recommended dose to treat chronic migraine, severe underarm sweating, blepharospasm, strabismus, or when BOTOX® Cosmetic has been used at the recommended dose to treat frown lines, crow’s feet lines, and/or forehead lines.