With any injection there is a risk of redness , bruising , pain, bleeding , swelling and infection. Treatment to this area is usually uncomplicated.  There is a small risk of bruising at the injection sites at the outer part of the eyebrow.
Wrinkle relaxer injections  in this area can result in spread or diffusion  into the surrounding eye muscles. The muscles that are treated are very close to the muscle that lifts the upper eyelid. If this muscle is affected it can lead to temporary dropping of the eyelid 'ptosis '. This is a very rare (<0.1% ) occurrence and usually wears off within 2-4 weeks.