Side effects are very rare. 3% of patients experienced eyelid drooping in frown lines studies and 1% of patients experienced eyelid swelling in crow’s feet studies. Other possible side effects include: dry mouth; discomfort or pain at the injection site; tiredness; headache; neck pain; eye problems: double vision, blurred vision, decreased eyesight and dry eyes; and allergic reactions. Ask your skincare professional for more information about side effects or any other concerns you may have about the procedure.