Phosphodiesterase 5-Inhibitors (PDE5I) are the first line of treatment for erectile dysfunction (ED), however, two-thirds of ED patients are diagnosed as PDE5I non-responsive after taking PDE5I with little or no effect. A recent study suggests that the lack of response to the drug is likely due to incorrect use of the drug by patients. Dr. Javier Romero Otero and others at the University Hospital 12 de Octubre in Spain conducted a study to increase patient education while using PDE5I. The study included 250 patients who attended the hospital’s male unit between 2010 and 2011, 39% of whom were taking sildenafil (Viagra), 37% were taking tadalafil (Cialis), and 24% were taking vardenafil (Elidel), with no significant results. The results of the study were published online in Urology. Of the 250 patients, nearly 70% (172) did not take their medication as prescribed at least once, and nearly 30% did not take their medication as prescribed up to three times. For example, 1/3 of the patients did not take the drug more than six times, when the improvement curve flattens out after six to eight doses are reported; 1/5 of the patients did not take the drug on an empty stomach, but fasting is important with sildenafil and vardenafil; and 1/3 of the patients did not use the maximum dose. The researchers “re-educated” these 172 patients by explaining to them the proper use of ED medications. Of the remaining 115 patients, more than 3/4 began to respond to the medications, and less than 1/4 were proven to be true non-responders. No statistical differences were shown between the three drugs. The study found that the most common error made by patients was trying only one PDE5I, followed by not using the drug 6-8 times, and that these incorrect uses all affected the effect of the PDE5I. The authors concluded that physicians should recognize the importance of educating patients and recommend that primary care physicians explain in detail the proper use of PDE5I to patients to prevent false non-response.