Answer: Botox is a safe treatment modality and has been used since the 1980s with great results. There is always the risk of bruising but this is minimal. Depending on the strength of your muscles, the effects of Botox can last from 2½ months to 4 months on average after the first treatment. As the muscles involve relax over time, this can lengthen and typically patients require less Botox over subsequent treatments.