I am wonder if one needle of botox to the forehead it's means One unit?

The units of Botox are mixed in the solution within the syringe. So if you are having 20 units, it does NOT mean that you need 20 shots. Generally if you are having 20 units between your eyebrows, this is delivered with 3 to 5 gentle pokes of the needle. However, don't be afraid. The needles used for Botox are the smallest needles made. Additionally, most doctors give you a numbing cream prior to the injection or ice applied to the area prior the injection. However, as most people who have Botox regularly will tell you, the injections do not hurt at all when given properly. If you are being treated by an experienced and qualify and ethical injector, they will take the time to explain what the units mean and give you the proper number of you that you are paying for. Different patients require different numbers of units to achieve the desired effect from Botox. Good Luck.

Having 20 units of Botox will not mean you’re going to have 20 injection sticks spread across your forehead, depending on how strong your muscle movement is will determine how many units on each area you would need, most patients require 2-8 units per site

20 units of Botox is within the normal range to treat the forehead. Those 20 units could be given through a varied number of injection points, depending on the technique and the injector. I would say on average, it might be around 5-10 injection points to treat the forehead. (When you say needles, I am assuming you mean injection points).

The number of units of Botox per each injection depends in how your doctor reconstitutes Botox. Each injection can contain between 1 and upwards of 5 units of Botox, depending on the area of the forehead that the doctor is treating. For example, to treat the horizontal lines across the forehead, I typically use a lot of small injections. On the other hand, when treating the frown lines between the brows, I inject lager amounts with fewer injections. The number of injections varies from person to person based on their anatomy and the strength of their muscles.

depending on the severity of the wrinkles with most people coming in the middle of the range...each shot typically contains more than one unit...and with some numbing cream or ice the process is basically painless...

There are 50 or 100 units in each vial of Botox Cosmetic (depending on which size vial is being used). This is the active amount of the neuromodulator. That doesn't mean that an injector only puts 1 unit in with each point of injection. Usually between 2-6 units are put in with each injection site depending upon which muscle is being treated. You will not need 20 needle sticks for 20 units. "This answer has been solicited without seeing this patient and cannot
be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."