Contrary to popular belief, there are other prescription medications that can be used to treat erectile dysfunction (ED) besides Fildena 100 vs viagra. In order to prevent overdosing symptoms, do not take more than one pill of the prescribed medication within 24 hours of the preceding dosage. The medication can be taken orally half an hour before engaging in any sexual activity, along with a glass of water. Be sure, though, to swallow it whole. Don't chew or crush the prescription drug. After drinking a glass of water, swallow one entire Fildena 100. A pill will lose some of its effectiveness if it is broken, chewed, or crushed before usage. One of the closest PDE5 inhibitor medications is Fildena 100, which is a generic version of Viagra.