Cenforce FM 100 mg contains sildenafil 100 mg (a PDE-5 inhibitor) along with ingredients that may vary by manufacturer (some “FM” products are marketed as sildenafil formulations with additional components). Dehydration is not a commonly reported side effect of sildenafil. However, some effects can feel like dehydration or contribute to fluid loss in certain situations: Headache, dizziness, flushing, or dry mouth can occur and may be mistaken for dehydration. Drinking alcohol with it can worsen dizziness and contribute to dehydration. If you are exercising heavily, sweating a lot, or not drinking enough fluids, you may become dehydrated independently. What you can do: Drink enough water, especially if you are active or in hot weather. Avoid excessive alcohol when taking it. If you experience severe dizziness, fainting, confusion, very low blood pressure symptoms, or prolonged erection (more than 4 hours), seek medical help. If you tell me what symptoms you are having (dry mouth, thirst, dizziness, dark urine, weakness, etc.)