Harms: adverse effects on exercise; side effects: causes muscle stiffness. Slimming injections are usually achieved by injecting botulinum toxin to make the muscles in a body part smaller. Because the motor system through the innervation of muscles for coordinated movement, injection of botulinum toxin is more likely to make a muscle atrophy, which will have a negative impact on the movement; easy to cause local muscle stiffness, and may even appear in the injection site of redness, pain, and swelling and other phenomena.