Get emergency medical help if you have signs of insulin allergy: redness, swelling, sweating, itchy skin rash over the entire body, trouble breathing, fast heartbeats, feeling like you might pass out, or swelling in your tongue or throat. Call your doctor at once if you have: low potassium--leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling. Common side effects may include: low blood sugar; swelling in your hands or feet; weight gain; or thickening or hollowing of the skin where you injected the medicine. This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.