Lemonaid Sildenafil. Skip to review. Best for bulk ordering Viagra and generic Viagra: Optum Store Viagra. Best subscription service for Viagra and generic Viagra: Rex MD .The following information includes only the average doses of this medicine. If you experience a prolonged or painful erection for 4 hours or more, contact your doctor immediately. If you have certain health conditions or are taking certain medications, your doctor may tell you to take sildenafil less often. Store mixed oral liquid in the refrigerator. Do not start these medications while taking sildenafil without discussing it with your healthcare provider. It can be dangerous to take sildenafil if you also take medicines called nitrates often given for chest pain.AdGet a Prescription for ED treatment, discreetly deliverED to your e Catalog: P.E. Treatments, GET MORE INFO, Terms & Conditions, Instagram and more. Lemonaid Sildenafil. Skip to review. Best for bulk ordering Viagra and generic Viagra: Optum Store Viagra. Best subscription service for Viagra and generic Viagra: Rex MD . AdEnjoy Greater Libido & Performance. Fast Express Shipping.The following nonprescription or herbal products may interact with sildenafil: cimetidine Tagamet HB , St. Rarely reported side effects include: an erection that will not go away priapism. Remove the cap by pushing it down and twisting it counter-clockwise. Keep from freezing. If you have an erection that lasts more than 4 hours, get medical help right away. The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. If you take too much sildenafil or take it together with these medicines, the chance for side effects will be higher.