The present invention provides a method of increasing the efficacy of treating a muscle or sweat gland hyperactivity condition in a human or mammal with a neurotoxin. The method includes adding a quantity of either a diffusion-limiting agent or an anti-metabolic agent to the neurotoxin. Adding the agent to the neurotoxin leads to the formation of an agent/neurotoxin injection mixture. The quantity of agent added is sufficient to increase a therapeutic response of the human or mammal's sweat gland or muscle to the neurotoxin compared to what the response would have been had the human or mammal been treated with neurotoxin alone. The present invention provides a kit for treating a muscle or sweat gland hyperactivity condition in a human or mammal. The kit includes a needle, a solvent, a neurotoxin, and either a diffusion-limiting agent or an anti-metabolic agent.