Failure rate of 50% Out of 117 men who were suitable for taking sildenafil, the acceptance of sildenafil as a treatment option is high, 98.3% (115/117). Sildenafil was successful in treating ED in 91.3% (84/92) of this study population. At the end of the study period, 79.7% (59/74) of men wanted to continue treatment with sildenafil. The side effect profile of sildenafil in this study would appear to be different from previous published data [6] in that the incidence of headache, flushing, dyspepsia and abnormal vision is higher, but in the absence of a control group the significance of this is uncertain. It must be noted that 13% of men who reported side effects at Visit 2 reported complete lack of them at Visit 3. It is of interest that there is a 2% incidence each of thirst and 'dazed feeling' (reported by patients as a 'muzzy head'). The physiology underlying this is unclear, although it could be related to PDE inhibition in the brain, where the various PDE isoenzymes are in abundance [11]. External vacuum therapy Safe Condoms offer the most protection against STIs of all the barrier method options. Using a spermicide with condoms can offer better protection against pregnancy, but it does not increase your protection against STIs . Spermicides containing nonoxynol-9 can cause genital irritation and can actually increase your risk of catching an STI. buy cialis 60mg here where to buy cialis without prescription