Sildenafil
"My partner has ED occasionally. He was advised to try Viagra. It was effective after about 2 hours when he achieved a really veiny, stiff erection. This was a great improvement and lasted as long as we needed and again the next morning, however, the side effects were unpleasant flu like symptoms ( ie. headache, sore throat, blocked nose etc.) which lasted for many days after. For this reason and due to the high expense we will only use this on 'special occasions' from now on, until we find an alternative."