With the influx of new skin-care procedures, treatments, and products that has hit the market in recent years, one has truly lasted the test of time — 14 years, to be exact — and it seems to be getting even more popular. You've heard of it. Everyone has heard of it. It's called Botulinum toxin, a.k.a. Botox.Maybe you know someone who's tried it, or maybe you've tried it yourself. ( No judgment. ) But with this injectable treatment, there is a lot more than meets the eye. Ahead, 20 things you might not know about Botox.Botulinum toxin has been the number-one nonsurgical procedure since 2000. As of 2015, there have been 4 million procedures performed.Botulinum toxin was first used as a medical treatment for strabismus (a muscle-related eye condition) in the 1970s and '80s. Soon, it was discovered that it also helped treat face and neck spasms, among other medical conditions.The cosmetic benefits came to light in the 1990s by happy coincidence. “The aesthetic indications were purely happenstance,” says board-certified surgeon and clinical professor Seth L. Matarasso, MD , who has been treating his clients with Botox since the 1990s but is not affiliated with the brand. “ Dr. [Jean] Carruthers was working with patients with strabismus...[and] with diplopia [double vision], and her patients were coming in and saying, ‘Gee, my wrinkles are better.'" Soon enough, doctors were using Botox for what it is most commonly associated with today — nixing lines.“This product has been around for a very long time,” says Dr. Matarasso. “It’s safe and it’s effective. I don’t think there are many other products that have been studied as extensively as Botox."The FDA approved cosmetic Botox in 2002. But to this day, it is only approved for three purposes in the dermatological world: in-between the eyebrows, the lines around the eyes, and sweating under the armpits.Just because not every cosmetic Botox procedure is FDA-approved doesn't mean it's not safe and effective, if done properly. Off-label procedures are still within the standard of care, and there are tons of them. “There are so many non-FDA-approved applications for Botox,” says dermatologist Dendy Engelman, MD . “It can be used to decrease scalp-sweating (which helps prolong blowouts), correct a droopy nasal tip (called nasal-tip ptosis), fix brow asymmetry, minimize bunny lines from wrinkling your nose, decrease skin oiliness, minimize the appearance of pores...” The list goes on and on.Many people who experience excessive sweating, whether on their hands, hairline, or even under their breasts or butt, are turning to Botox and other neuromodulators (like Xeomin or Dysport). "They help prevent excessive sweating by acting on the sweat glands directly," says NYC board-certified plastic surgeon Z. Paul Lorenc, MD . "The neuromodulator is injected into the sweat glands to relax the muscle and help combat excessive sweating.""I have treated people with profound migraine headaches and it turns them right off," says Dr. Matarasso. "If you feel it coming on, it stops it, reducing the severity as well as the duration. I had a patient [who was] in college who had unremitting migraine headaches. She changed her diet, she changed her birth-control pill, she had acupuncture. I finally said to the mother, 'We need to try Botox,' and it has been a complete life-changing event for this woman."One of the "stranger" uses may be the injection of Botox into bladder muscle to help with an overactive bladder, according to some doctors.“I don’t think it is physically addictive,” says Dr. Matarasso. “But, I have to be very frank with you, when I get a new patient I tell them (and I say this tongue-in-cheek) this product is truly addictive. I make jokes with my patients that we need a 12-step program for it, because when it’s done correctly, it’s a very simple office procedure, with impressive cosmetic results.”He says the problem is when people go overboard. “They say, ‘Okay, I did my crow’s feet, that’s fabulous. I did my lines under my eyes, that is terrific. I did my forehead. Where else can I go?’ Then you do the neck, then you do the chin…then you just start looking like a doll.”Dr. Matarasso says hardly a week goes by when he doesn’t see a patient with a botched Botox job. Why? People are getting it done by unexperienced, often unlicensed, practitioners who don’t know the shape of the face and how to correctly administer the toxin. “I just had a patient come in the other day who went to an ER doctor, and one that went to a psychiatrist,” he says. “They [also] have these Botox parties and I have seen scarring, significant bruising, not only functional, but aesthetic complications.”Botox is so commonplace these days that you can get it done at some gyms and spas, but in these cases, you never know what you’re getting, how old the product is, with what it's mixed, and whether the injector knows what he or she is doing. Dr. Matarasso suggests only getting it done by what he calls the “core four”: a board-certified physician who is either a dermatologist, a plastic surgeon, an ear-nose-and-throat doctor, or an ophthalmologist.“You are not looking for a skating rink on your forehead; you want movement, you want some lines,” says Dr. Matarasso. “You want to be able to be demonstrative.”“I turn away a fair number of patients who want more Botox before I deem it appropriate,” says Dr. Engelman. “I try to establish a trusting relationship from the initial consultation in order to allow the patient to know that I will tell them what they need and when, but also won't let them do procedures prematurely or unnecessarily.”When asked how often he turns people away, Dr. Matarasso says: “I turned someone away today. I had a gentleman come in, he was an appropriate candidate anatomically, he had some deep lines in his forehead, but his expectations were unrealistic. He wanted every line erased, and I said, ‘No, you are going to look a little mask-like.’ I gave him a brochure and said, 'Go home and think about it.'”According to the American Society of Plastic Surgeons, men’s Botox treatments are up 337% from 2000.Unlike some resurfacing or surgical procedures, after which there is possible pigmentation or scarring, when Botox is done correctly, it can be done on all skin tones. “This is a procedure [and] product that crosses all divides,” says Dr. Matarasso. “Men, women, Caucasian, African-American, Asian, Indian. I don’t think there is a demographic that has not enjoyed the benefit of this product.”Aesthetician Mary Schook is anti-Botox because she sees the long-term effects on her clients. “Everyone is always like, ‘Look how great this looks,’ and then there is the long-term and they are like, 'Fix me,'” she says. “Allergan [the company that owns Botox] says one in 100 patients gets eyelid-drop, so I always joke, ‘I must meet one in 100 patients, because everyone I see has that drop.'”She thinks that it is not necessarily a function of the product itself, but rather about the application. “I get so many phone calls, like, 'My eyelids have dropped, can you fix it?' So I do lymphatic drainage and special electricity to help activate the muscle again.”It’s a gradual onset, so it won’t kick in for two or three days, up to seven. Once it does, it lasts three or four months. Each time you do it, according to Dr. Matarasso, it will last a little longer.Dr. Engelman says preventative is legit.“Most certainly! I do micro-injections on patients who are just starting to show the finest expression lines in order to prevent them from ever making the wrinkle." NYC-based board-certified plastic surgeon Norman Rowe , MD, is also a fan. "While Botox has a fundamental use in treating wrinkles that are already formed, it has a role in the prophylactic, or prevention, of wrinkles. So, don't think that you don't need Botox because you don't have wrinkles. If you want to keep that smooth skin, start with Botox before they form."But in a recent Fat Mascara podcast, NYC dermatologist Pat Wexler, MD, said this is a myth . And Dr. Matarasso falls somewhere in-between.“For aesthetic or cosmetic reasons, does a 19-year-old need this? No. Does a 26-year-old need this for aesthetic purposes? Highly doubtful. But, hey, listen, if you are like, ‘I am looking at my parents, I am looking at my genes, and I want to stay proactive,’ it is not unreasonable to introduce it in small amounts.”“A younger face has a heart shape, and an older face is a little more bottom-heavy and square,” says Dr. Matarasso. “But if you put toxin in both sides, you are not reducing the movement of the muscle, you are thinning the muscle out a bit. You can restore a youthful look. It’s not as dramatic or quick-acting as other areas, but it can be a nice way to improve the contour of the face.”Not only are we being more versatile with it (hello, neck and butt), but we use less of it in a sitting. "Where we used to really want paralysis, no movement, we are now using smaller amounts," says Dr. Matarasso. "You are not paralyzing the muscle, you are relaxing the muscle.”