When one reads side effects of any drug, the FDA will list all symptoms that study participants felt when undergoing the trial. If someone were to be developing the flu without enrolling in the study, and never having Botox, then their symptoms of nausea, muscle aches, fever, etc. would not be blamed on Botox. If however, a study participant were to coincidentally develop a headache, of flu symptoms, these symptoms would have to be listed. The percent of these reactions developing out of all study participants is usually listed, and sometimes the percents related to the botox individuals is less than in the population that received placebo. Double vision can be caused if the botox is injected too close to the eye muscles, but this rarely happens with cosmetic Botox, possibly more with eye doctor treatment of lazy eye muscle disorders. I am not aware of my patients having developed anxiety or seizures in the 18 years of my administering Botox, nor have I heard colleagues mention this of their patients. Overdoses of any product, including non-prescription pills, such as aspirin and tylenol, can cause serious symptoms including seizures but that rarely stops someone from taking the correct dose if they need the medication.