Botox for Underarm Hyperhidrosis
The Minor Test
Some may administer the Minor’s starch iodine test to determine the location of the sweat glands in the axilla, which provides a template for treatment. In our practice, we rarely apply the starch iodine test; instead, we define the hyperhidrotic area of each axilla according to the hair- bearing area, which is delineated with a marking pen prior to administering a betadine prep.
We inject botulinum toxin in the axillary area with a 26- or 30-gauge needle on a TB syringe. In most patients, 40 evenly-distributed injection sites are placed subdermally in each axilla (20 injections per milliliter of injection solution), with the injection sites approximately 8 mm apart. The needle is inserted at a 45-degree angle, approximately 2 mm. The injection should be performed in one smooth motion to reduce trauma to the area. The total injection volume per axilla is 50 U of reconstituted BoNT-A, which was found to be the minimal dose necessary to cause anhidrosis in healthy volunteers.In most patients, these 50 U is diluted in 2 mL of normal saline, but in patients with larger axillae, up to 3 mL is occasionally used to reconstitute 50 U.