Botulinum toxin unit: what the dose means

The dose of botulinum toxin is expressed in units (U), not in milligrams or milliliters. The unit is a measure of biological activity: each manufacturer defines what 1 unit of its product is based on its own assay. For this reason, the number of units only makes sense together with the product name.

Why are units not interchangeable?

Because each product uses its own standardization method, the same numerical amount of units can correspond to different effects in different products. The labels themselves usually state that the units of one product are not interchangeable with those of another. Switching products requires reviewing the dose based on the label and clinical experience, not applying a fixed conversion.

And the dilution volume?

The freeze-dried product is reconstituted in saline, and the volume used for dilution changes the concentration, not the dose. Two injections with the same volume in ml can contain very different numbers of units, depending on the dilution. That is why the correct record is in units per injection point, with the product, lot and dilution noted in the patient record.

The total dose per area varies with muscle strength, sex, anatomy and goal, and is defined by the licensed professional, after assessment.

In Harmy

Harmy's Plan works with a value per area to guide the projection. In toxin areas, such as the Glabella, that value works as a reference for the simulation and does not represent the dose in units. The actual dose stays in your patient record.

Also called: U, toxin dose.