According to the American Society of Plastic Surgeons, women in their 20s make up 30 percent of Botox users -- a statistic Bowe sees reflected in her patients.

For those in their early 20s, Bowe typically doesn't recommend injections for wrinkles, but she does use Botox to improve facial symmetry (a droopy brow, for instance). While no face is perfectly symmetrical, symmetry is one of the biggest factors in attractiveness.

Diagnosis: For our 22-year-old staffer Amanda (at right), the first and only thing Bowe zeroes in on are her "angry 11s" -- the lines between the eyebrows resulting from furrowing the brow. You can barely see them here (we sent Bowe painfully high-resolution images of our faces), but Bowe says they're an indicator of wrinkles to come.

Treatment: Because of her young age and because these aren't "etched-in" lines (deep wrinkles apparent when the face is expressionless), Bowe says she wouldn't recommend Botox -- yet.

For now, she simply advises her to be aware of her facial expressions -- she's probably furrowing her brows without noticing it, and to use a retinol at night and sunscreen during the day. We recommend Roc Retinol Correxion Night Cream and Kiss My Face Face Factor Sunscreen .

By 27, Amanda might benefit by coming in once a year for very light injections to the muscles between the brows.

Annual Cost: $300 a year

While Bowe says most people in their early- and mid-20s don't need Botox, it can be a way to discourage the kind of dramatic expressions that lead to permanent wrinkles. She compares it to putting a cast on a broken arm or leg -- if you can't move it, your body has the chance to repair it. Plus, the patient learns to relax it more often.

Diagnosis: According to Bowe, 24-year-old Allie, shown here, doesn't yet need preventative Botox, but Bowe can point out areas where she may need it in the future.

"She has one vertical crease between her eyebrows. Most people have two, but her facial structure and expression habits have created just one. I can also tell she is someone who will struggle with under-eye issues." Her thin skin and fair complexion means sun damage (aka wrinkles) will show up right away.

Treatment: Bowe rarely treats wrinkles in patients under 25 with injections, though she says sometimes she will in cases of extreme damage from the sun. For now, she recommends broad-spectrum sunglasses and a good eye cream with peptides, which trigger collagen formation and help form elastin. We like Juice Beauty Green Apple Brightening Eye Cream.

In a few years, Bowe predicts a patient like Allie could benefit from about six to ten injections every six months between the eyebrows and the outer border of the eyes.

Annual Cost: Between $100 and $200

Late 20s is when Bowe starts to see serious candidates for what she calls "prophylactic Botox." The typical case? Fair-skinned individuals who have had a lot of sun exposure growing up.

Other candidates are those who constantly exaggerate facial expressions without realizing it -- the frowners, the squinters, the smilers and the eyebrow-raisers, says Bowe. "By using Botox in a prophylactic way, I actually retrain these muscles to react in a gentler way. I'm still allowing these muscles to move, but not in such an exaggerated way as to lead to etched-in wrinkles," says Bowe.

Diagnosis: Bowe says Emily, 27, is a perfect example of someone with very fair skin, so even a little sun exposure shows fine lines. Emily's forehead lines are horizontal (she's probably one of those "surprised" people) and she has fine lines around the eyes.

Treatment: "Even though her skin looks young and healthy, I would be a little more aggressive to smooth out those lines," says Bowe. "To treat these issues, I can usually get away with using less than 25 units per session, costing the patient $400 to $450. Using such a small amount means that the expression isn't affected -- no frozen faces. I find that I only need to treat these patients twice a year in order to get a very nice result," says Bowe.

Annual Cost: $800-900

Bowe has a self-test for determining who can benefit from Botox in their early 30s: If you find yourself smoothing makeup that collects along a crease or line, you're a good candidate for Botox.

Diagnosis: Bowe says Mary, 31, actually doesn't need to worry about frown or forehead lines. What Bowe does notice is a slight asymmetry. "Her right brow at rest is slightly more sloped downward. When she smiles it pulls down more, almost making the right eye appear smaller. If she doesn't address that early on, the right eye will continue to look smaller and the brows will slope down."

Treatment: "To prevent that, I would lift the eyebrow into an arch. I would put a drop into the outer corner of the right eyebrow," says Bowe, adding that it'd make her look more awake and her face would be more harmonious.

To treat typical creases (usually frown and forehead lines) for someone in her early 30s, Bowe would use 25 to 30 units per treatment every three to six months, depending on how pronounced the lines are. If you were (or are) a smoker, or someone with a lot of sun damage, Bowe says you may require a few more units.

Annual Cost: $1,800 to $2,700

Laura, pictured right, is proof that age isn't always the best test for when you need Botox. Bowe says she looks younger than her age (35), and can probably hold off on preventative Botox for another three to five years.

Diagnosis: Bowe does note that Laura might benefit from Botox under each eye to treat what derms call the "jelly roll" -- the roll of skin that forms under the eye when some people smile. "By treating that, her eyes will stay more widely open when she smiles," says Bowe.

Treatment: In a few years, Bowe says that a patient who is a "smiler" like Laura might benefit from a drop of Botox to lift her eyelids and eyebrows, as well as a few drops to smooth out her crow's feet. For now, one unit under each eye every three to four months would give Laura a more wide-eyed smile, a request Bowe receives from patients of all ages.

Annual Cost: $120 to $160