Which One is Safer? These PDE5 inhibitors may cause headache, flushing, drop in blood pressure, or other adverse effects. For some, one can be more effective than the other. How do you choose which one is better for you? Those who don’t feel comfortable discussing ED with an in-person provider or lack time to visit a doctor’s office may find online ED prescriptions beneficial. This is particularly true if you have any heart conditions or health problems. The specific process for getting ED pills online depends on your chosen provider.How we vet brands and products Erectile dysfunction medications, including Viagra and Cialis, help the muscles in the penis relax so you can get and maintain an . Was this helpful? How does Cialis work? Cialis works by increasing blood flow to the penis to help a person get and maintain an erection. It also blocks the PDE5 .