Do you feel like everyone you know is suddenly singing the praises of Botox? (No more frown lines!) In certain circles of 20- and 30-somethings, dialing up a derm for a shot of Botox seems to be as popular—and as totally normal—as scheduling a bikini wax appointment.That makes sense because, according to the most recent data released by the International Society for Aesthetic Plastic Surgery, Botox is now the most popular world-wide nonsurgical procedure performed by plastic surgeons. In 2012, a whopping 6.1 million Botox treatments were administered in the United States alone—93,000 on 20-somethings, up 8 percent over the year before. Here’s why it’s so popular: “Botox is one of my favorite products because we know down to the molecule how it works. There is no mystery. We can put it exactly where we want it and we know how it’s working,” says Doris Day, M.D., who owns a private practice in New York City and is a clinical assistant professor of dermatology at the New York University Langone Medical Center.So if you haven’t tried it yet—but are increasingly curious—here’s everything you need to know.How it works. Botox is a prescription medicine that is injected into facial muscles to temporarily minimize the appearance of moderate-to-severe wrinkles. It’s approved by the FDA to reduce “the elevens,” which are the vertical lines between your brows that are caused by frowning, but doctors use it all over the face, like on the forehead, around the lips and even on the neck. “Botox blocks an enzyme called acetylcholine at the presynaptic nerve endings, which basically blocks the nerve from recognizing a trigger to move a muscle,” says Dr. Day. By reducing muscle activity, wrinkles caused by repeated and involuntary facial expressions are minimized. But, watch out. You don’t want your doc to knock out the impulses completely, but rather just soften the reflexes. This lighter approach is what makes the difference between feeling like your forehead is totally frozen and actually being able to create natural facial movements. This non-invasive procedure usually takes about 10 minutes and there’s no downtime. It takes about two days to start to see the results and three weeks to see the full effects.How long does it last? One Botox treatment lasts about three to four months, then slowly starts to wear off as your muscles go back to the way they were.Does it hurt? Some people may feel pinching or stinging, but for only the few seconds the needle is injected into the skin. “We use one of the smallest needles you can get because Botox is a thin liquid,” says Dr. Day. You can ask your doctor to numb the area first with a cold pack or anesthetic cream.Should you start at a certain age? “I never ask someone’s age, but rather I look at their face to see if they need it or not. I have 50-year-olds who don’t need it and 20-year-olds who are overdue. Many people make negative gestures like frowning or pursing their lips for every expression they have, without even realizing they are doing it. It often starts at childhood and that’s when your mom would tell you, ‘Don’t keep making that face or one day it’ll stick!’ ” says Dr. Day. Young women who involuntarily tend to furrow their brows or squint their eyes don’t convey an image of confidence or happiness. “A Botox treatment evens out the playing field. By taking away the negative, I’m really accentuating the positive,” says Dr. Day. Plus, more women in their 20s are starting to use Botox as an anti-aging treatment. The less frown lines you make, the less pronounced, or etched in, your wrinkles will be as you age.What are the risks? Botox is FDA approved. “It’s very safe, effective and has been around for over 20 years,” says Dr. Day. But, like any kind of medical procedure, there are still risk factors—namely, the competency of the doctor doing the injections. “It’s all about the finesse and experience of the doctor because properly placing Botox is not intuitive. You don’t put it exactly on the wrinkles you want to reduce, but rather on the muscles that cause those wrinkles, which could be above or to the side of them—it’s not always obvious and there are many subtleties involved to get natural, even results,” says Dr. Day. Don’t get the treatment if you have an infection on the area you want treated, or are pregnant or breastfeeding. Tell your doctor if you have any type of disease involving muscle weakness.How much does it cost? The cost of one Botox treatment ranges from $450 to over $1,000 depending on the doctor’s fees and how much Botox was injected. “Don’t cut corners. The more experienced doctors charge more, but then you know you’ll be getting a good treatment. Good results are all about going to a good doctor,” says Dr. Day.Can you reverse the effects if you don’t like it? No. If you’re unhappy with the results, you can ask your doctor if there’s anything he can do to even things out if drooping or uneven brows is the case, but you’ll have to wait for the Botox to wear off for your face to go back to the way it was. That’s why it’s so important to go to a good doctor.How do you find a good doctor? Word of mouth referrals are ideal. If you like the way a friend who’s had Botox looks, then you’ll like the way her doctor works. You can also research online for the best doctors in your neighborhood. Schedule a consultation with a board-certified dermatologist or plastic surgeon and ask how long he’s been doing Botox and if he will do the treatment, not his assistant. “This is not a routine procedure, so I always do injectables myself. In the case of Botox, one size fits none,” says Dr. Day. Also, during your consultation visit, pay attention to the aesthetics of the doctor and his staff. “You know the doctor is most likely doing treatments for his staff, so if you think they look great, that’s a good sign,” says Dr. Day.