Fildena 100 mg is a medication used to treat erectile dysfunction (ED) in men. It contains sildenafil citrate, which is a phosphodiesterase type 5 (PDE5) inhibitor. The effects of Fildena 100 mg typically last for about 4 to 6 hours. It's important to note that the medication does not cause spontaneous erections; sexual stimulation is still required to achieve an erection. Common side effects of Fildena 100 mg may include headache, dizziness, flushing, indigestion, nasal congestion, and changes in vision. These side effects are usually mild and temporary. However, if you experience severe or persistent side effects, contact your doctor.