Certain liquid medications, including suspensions and emulsions, must be shaken before use to ensure proper mixing of active ingredients. For example, some antibiotics and antacids are suspensions that need shaking. According toCanadian Insulin Reviews, insulin suspensions, like NPH insulin, also require shaking to ensure a consistent dose. Without shaking, the medication can settle, leading to incorrect dosing and potentially ineffective treatment. Always read the label or consult your pharmacist to know which medications need shaking before taking them.