Side effects are generally non-existent or very mild. On occasion, you may experience some discomfort, bruising, redness, itching, inflammation, or redness at or around the site of injection that could last from a few minutes to several days. True allergic reactions are extremely rare. However, if you experience throat swelling, pruritic body rash, dangerously low blood pressure, or symptoms associated with anaphylaxis following administration of an injection, visit your nearest emergency department. If you know you are allergic to any of the ingredients — please avoid it!