Erectile dysfunction medications require a prescription from a licensed provider. The most common side effects of VIAGRA: headache; flushing; upset stomach; abnormal vision, such as changes in color vision such as having a blue color tinge and blurred vision; stuffy or runny nose; back pain; muscle pain; nausea; dizziness; rash. However, others work on a cash-pay basis and don’t partner with insurance companies. There are many safe, reliable online services offering ED prescriptions. While each PDE5 inhibitor differs slightly, they’re very similar in treating erectile dysfunction. The information provided is for educational purposes only and is not intended to replace discussions with a healthcare provider.Viagra is available in mg, mg, and mg doses and can be purchased in day and day supplies. Shipping is free, and your new medication can be sent discreetly to your home. Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is mg. Don’t take sildenafil (Viagra) more than once daily (at any dose). Written by Brian Leonard, PharmD, BCACP, BCGP. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung condition. This drug is more popular than comparable drugs. It is available in generic and brand versions.