Tadalafil is a prescription medication that many family physicians prescribe to male patients that are suffering from the symptoms that are most commonly experienced when they have problems with sexual functions such as erectile dysfunction or impotence. The way this drug works is it effectively blocks phosphodiesterase-PDE5, which is a specific type of enzyme that is produced within the body. When sexual stimulation is used along with this type of medication, the blood that flows to the genital area of the patient allows him to successfully achieve an erection for sexual activity. It is advised that this drug be taken approximately 30 minutes prior to any type of sexual activity to receive the most benefit, and the effects of this medication last as long as 36 hours. Some of the most common side effects that some individuals experience while using Tadalafil would include changes in the vision, headache, dizziness, an upset stomach, pain felt in the legs or the arms, back pain, flushing, muscle pain, and stuffiness of the nasal passages.