John’s wort. You can take this medicine with or without food 30 minutes before sex, depending on the dose. The four main medicines taken by mouth for erectile dysfunction are: Avanafil Stendra. This is likely to lead to dramatic price reductions. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail. The following nonprescription or herbal products may interact with sildenafil: cimetidine Tagamet HB , St.Viagra is an effective drug for treating male erectile dysfunction, but it targets sexual performance, not sexual arousal. There is limited evidence that Viagra may be beneficial for women with sexual dysfunction, but the .  · a light-headed feeling, like you might pass out. Common sildenafil side effects may include: flushing (warmth, redness, or tingly feeling); headache, dizziness; heartburn, nausea, or upset stomach. abnormal vision (blurred vision, changes in color vision) runny or stuffy nose, nosebleeds; sleep problems (insomnia); or.  · Viagra; Descriptions. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. The .