An inhibitor of phosphodiesterase (PDE-5) is Zhewitra. It treats erectile dysfunction by relaxing the muscles in the penis' blood vessels, which increases blood flow to the area. An erection can only be beneficial if the person is sexually stimulated. Follow your doctor's advice regarding the dosage and length of time to take this medication. Eat it whole. Do not chew, crush, or break it. You can take Zhewitra 20mg Tablet with or without food, although taking it at the same time every day is recommended. Take one tablet without a meal one hour before having sex, and always check with your doctor before taking medication.