Botox has been approved by the FDA to smooth moderate to severe wrinkles on three areas: the crow’s-feet by the eyes (lateral canthal lines), frown lines between the eyebrows (glabellar lines), and forehead lines.

Providers inject three spots around each eye, five spots between the eyebrows, and five spots across the forehead. 

Note: The Botox forehead and face treatment areas listed above are FDA- and manufacturer-approved areas for injection. Some doctors will use Botox "off-label," which means injecting an area that isn't officially approved for injections. For instance, they might use Botox to raise the nasal tip for a faux rhinoplasty.

How many units of Botox do you need?

• How many units of Botox for foreheads?: 20 units total (4 units in each of the 5 injection sites across the forehead)
• How many units of Botox for frown lines?: 20 units total (4 units in each of the 5 injection sites between the eyebrows)
• How many units of Botox for crow’s-feet?: 24 units total (4 units in each of the 3 injection sites around the right eye. This is repeated around the left eye.)

Note: Forehead and frown lines are typically treated together, requiring a total of 40 units.

Remember, these are general guidelines. Doctors may need to inject more units to treat deeper lines or tougher skin. Women generally need fewer units than men. A consultation with your doctor will tell you exactly how many units of Botox you need to achieve your desired result.

How long does it take for Botox to work? How long do results last?

Botox face injections start working fairly quickly, and patients can typically see results in 24–48 hours. Optimal results are generally seen after 30 days and results last about three to four months.

Source

Information on injection sites, recommended number of units, and expected results comes from the manufacturer's website. Botox may cause serious side effects that can be life threatening. Read all of the safety considerations for Botox here.