To minimize excessive spread of botulinum toxin, patients keep their upper body upright for at least 2-4 hours after injection and it is recommended that they avoid compressing or rubbing the treatment area for 24 hours. Patients should contract and dilate the muscles in the treatment area as much as possible for 2-3 hours after treatment. The theory is that contracting the muscles will encourage neuronal uptake of Botox, thereby accelerating the onset of clinical efficacy. Side effects following botulinum toxin injections are usually mild and temporary, and typically include swelling or ecchymosis at the injection site, mild headache, or flu-like symptoms. Ecchymosis is most likely to occur after periorbital and perioral injections. For patients who can safely discontinue platelet function inhibitors (e.g., aspirin, vitamin E, alcohol), it is best to discontinue them for 7-10 days prior to periorbital injections. Botulinum toxin is an injectable neuromodulator derived from a neurotoxin produced by the bacterium Clostridium botulinum, which can cause botulism. By inhibiting nerve conduction between peripheral nerve endings and muscle fibers, botulinum toxin relaxes or paralyzes skeletal muscle. When used correctly, botulinum toxin injections are an extremely safe method of improving cosmetic imperfections caused or exacerbated by muscle contractions, such as visible frown lines between the eyebrows. The effects of Botox are temporary; muscle function usually returns to baseline within a few months.