Botox® prevents headaches in adults with chronic migraine before they even start, with about 10 minutes of treatment once every 3 months. so, ask your doctor if botox® is right for you, and if a sample is available. effects of botox® may spread hours to weeks after injection causing serious symptoms. alert your doctor right away, as difficulty swallowing, speaking, breathing, eye problems, or muscle weakness can be signs of a life-threatening condition. side effects may include allergic reactions, neck and injection site pain, fatigue, and headache. don't receive botox® if there's a skin i...