Start your consultation What does the process involve? See the full range that we carry above. How it works Complete online consultation Tell us your health history, select pick up in store or delivery, make payment. The four main medicines taken by mouth for erectile dysfunction are: Avanafil Stendra. Firstly, you can expect to take some form of online consultation for ED.How to use. Please read the enclosed leaflet carefully before use. • take 1 tablet approximately one hour before sexual activity. • swallow tablet whole with water. • do not take more than 1 tablet a day. Viagra Connect starts to work within minutes. You may take it up to 4 hours before sexual activity. Oral use. Sildenafil belongs to a group of medications called phosphodiesterase type 5 inhibitors. It is used for the treatment of erectile dysfunction (male impotence). It helps to achieve and keep an erection sufficient for sexual activity. It does this by allowing a greater blood flow into the penis when a man is sexually aroused. You should not use sildenafil if you are allergic to it, or: if you take other medicines to treat pulmonary arterial hypertension, such as riociguat (Adempas). Do not take this medicine .