Botulinum toxin is a neurotoxic protein produced by the bacterium Clostridium botulinum and related species. It prevents the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular junction and thus causes flaccid paralysis. Infection with the bacterium causes the disease botulism. Typically, the effects of Botox last for up to three to four months. If your facial muscles begin to train themselves to contract less, the period of time for each treatment may be extended longer than three or four months.