Typically the amount of BOTOX® and side effects and BOTOX® danger remains low. Any BOTOX® side effects can typically only last 6 months at a maximum, because BOTOX® treatments are temporary. People with neuromuscular disorders should consult with their physician carefully before having a BOTOX® injection treatment, as cardiovascular problems may arise. Likewise, those with cardiovascular disease should also pay special attention.

It is a natural response to assume there is some BOTOX® injection danger with a prosuct derived from a toxin, but it is in fact very safe, and has been is use for some time. It is always prudent to refview the BOTOX® injection side effects and procedure so that any BOTOX® injection danger is know and understood.

Some patients have been known to experience the side effects of BOTOX® of bruisng at the site of the injection. The most common BOTOX® side effects following the use of BOTOX® Cosmetic for glabellar lines are headache (13.3%), respiratory infection (3.5%), temporary eyelid droop (3.2%), nausea (3.0%), and flu syndrome (2.0%). Blepharoptosis is consistent with the pharmacologic action of BOTOX® Cosmetic and may be technique related. In rare occurences BOTOX® cosmetic can spread into neighboring muscles and cause temporary paralysis. In less that 1% of patients, this can cause drooping of the eyelid.

Less frequently side effects of BOTOX® occurring (<3%) adverse reactions included pain in the face, erythema at the injection site, and muscle weakness. These events are thought to be associated with the injection and occurred within the first week.

Source : http://www.botox-cosmetic-surgery.com/botox_and_side_effects.htm