There is one very important rule: you should only take Fildena once a day. If you take more than one pill in a short amount of time, you may experience side effects like headaches, flushing, dizziness, or even more serious problems like quick drops in blood pressure. Fildena is meant to be taken only when needed, right before planned sexual action. This is different from daily medicines for long-term conditions. If you keep taking it without a doctor’s care, your body may stop responding as well to the medicine over time.