When choosing one, tell your doctor or other health care professional what your preferences are, such as cost, ease of use, how long the drug’s effects last and side effects. Rarely reported side effects include: an erection that will not go away priapism. Try introducing toys or more oral sex to take some of the pressure off your penis to perform. Its effects often last for 4 to 5 hours. Getting a prescription for Viagra online is a good option if you want to keep things discreet and convenient. Counterfeit medicines can be very dangerous. Common ones include: Flushing of the skin.Not all of Roman’s ED products require a prescription. However, you do need one for Viagra. Roman sells both generic Viagra and brand-name Viagra, and they’re available in mg, mg, and. “The 5-mg difference between sildenafil and the lowest dose of Viagra could easily be made up by taking an extra half pill, if needed,” says Consumer Reports’ chief medical adviser, . Side Effects. Dizziness, headache, flushing, or stomach upset may occur. Vision changes such as increased sensitivity to light, blurred vision, or trouble telling blue and green colors apart may.