Before taking sildenafil, tell your doctor and pharmacist if you are allergic to sildenafil, any other medications, or any of the ingredients in sildenafil tablet or suspension. You should only be treated with one of these products at a time. That’s not to say there aren’t just as many illegitimate sites. Although not all of these side effects may occur, if they do occur they may need medical attention. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. We also looked at additional services, such as access to digital pharmacies and home delivery options. · You can take the drug 30 minutes to 4 hours before you anticipate sexual activity. Based on how well you respond to this dosage and any side effects you have, your doctor may either increase your. Viagra. Compare prices and print coupons for Sildenafil (Generic Revatio and Viagra) . 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.