I have seen occasional cases of incomplete muscle paralysis of the injected muscles, leading to an irregular contour upon frowning or raising ones eyebrows. This is either due to inadequate dosing of the Botox, or incomplete area of the muscle injected. Occasionally, patients may develop a small hematoma (bruise) at or near the injection site.
Hematomas can be mildly painful, unless the injector punctures the periosteum (membrane attached to the bone), in which case it can be quite painful. If hematoma is the cause, the pain will resolve soon. Anti inflammatories may be helpful, as well as warm compresses to the area. If hematoma is not the cause, you may require additional Botox to get complete weakening of the muscle.
I would suggest that you see a board certified physician (plastic surgeon, opthalmologist or dermatologist) who is well versed in the anatomy, pharmacology of Botox, and technique of injection when you get treated.
