Like all drugs, Botox is administered by dose. Every patient who has ever received it knows this well because they are charged some many $/unit. Much of the competition and advertising for Botox business is done by offering discounts by reducing the $ charge per unit. Patients often look astutely for who is offering the lowest $/unit this week or month. But what is a unit of Botox? A unit is a very miniature dose of Botox (a muscle poison) that causes a specific effect…death of a single mouse in a laboratory setting. Originally known as mouse units many years ago, Botox is known today just as a simple unit for understandable reasons. In case you were afraid that it may be deadly to humans, the estimated lethal dose in humans is around 35,000 units. The average cosmetic dose is a mere 20 to 40 units in most cases. This is why it is perfectly safe in cosmetic applications. Â