Xeomin may cause serious side effects, including allergic reactions. Symptoms of an allergic reaction to Xeomin may include itching, rash, redness, swelling, wheezing, asthma symptoms, dizziness, or feeling faint. Tell your doctor or seek medical help right away if you have wheezing, experience other asthma symptoms, or if you become dizzy or faint. In clinical trials of Xeomin for the treatment of frown lines between the eyebrows, the headache was the most common side effect. Xeomin may cause loss of strength or general muscle weakness, blurred vision, or drooping eyelids within hours to weeks of taking Xeomin. If this happens, do not drive a car, operate machinery, or do other dangerous activities. Tell your doctor if you have any side effect that bothers you, or that does not subside. These are not all of the possible side effects of Xeomin. For more information, see the accompanying Full Prescribing Information, including Medication Guide, or ask your doctor.