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. These side effects are caused by one of its primary ingredients, yohimbe. Your doctor will tell you not to take sildenafil if you are taking street drugs containing nitrates. Sildenafil comes as a tablet and suspension liquid to take by mouth. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist.1. Avoid taking Viagra with a large meal or high-fat meal. Viagra blood levels peak an hour after you swallow the tablet on an empty stomach. According to Ramin, if you eat a large or high-fat.  · 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. AdDon’t go to the pharmacy without checking prices at GoodRx® first. No commitment or fees. Find the lowest price in your neighborhood & use our free coupons to save up to 80%No Credit Card Required · Search & Compare PricesService catalog: Prescription Coupons, Prescription Discounts, Online Doct.