Laurie A. Casas, MD, FACS says:Anytime you have an injection, there is a risk for bruising. I always make sure my patients discontinue blood thinners 1-2 weeks prior to injections. Common blood thinners that make bruising worse are advil, aspirin, NSAIDS, Vitamin E, Fish oil, Avocado and alcohol to name a few. I also re...