How Does Viagra Work in the Body? It just improves the ability to have and maintain an erection which helps in sexual activity. If chest pains, dizziness, or nausea are experienced during sex, the exertion should be stopped and your doctor informed. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. How Should You Take Viagra?Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in adult males* with . Erectile dysfunction (ED) medications prescribed in minutes, deliverd to you in CANADA. Sildenafil (Viagra), Vardenafil (Levitra), Tadalafil (Cialis). Chat with us Any questions? . Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or alcohol. Its effects .