title: On call.  I am a 64-year-old man.  Aside from diabetes, I've been healthy and until now, the only prescription I've taken is insulin.  But I've been having trouble with erections, and my doctor just gave me a prescription for Viagra.  He also told me to be careful about using other drugs with Viagra but didn't give me a list.  Can you please fill me in?
authors.forename: Harvey B
authors.initials: HB
authors.lastname: Simon
mesh_terms: D000075202:Contraindications; D048909:Diabetes Complications; D004347:Drug Interactions; D004542:Ejaculation; D007172:Erectile Dysfunction / Q000188:drug therapy* / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000008:administration & dosage*; D011687:Purines / Q000008:administration & dosage; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage*; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate