Any injuries or surgeries you’ve had, especially ones that involve your penis, testicles or prostate. This similarity protects cGMP from degradation because sildenafil can bind to the catalytic site to act as a competitive inhibitor of cGMP-specific PDE-5, the enzyme that normally catalyzes the breakdown of vasodilatory cGMP. Often, these are prescribed for chest pain called angina. You then remove the vacuum device. Penis pumps have some other possible drawbacks: Erections that don’t feel like they used to. In summary, under the right circumstances and with ongoing motivation, ejaculation disorders can be overcome. Kidney disease that needs to be treated with dialysis.Since Cialis and Viagra are both PDE5 inhibitors and both are used to treat the symptoms of erectile dysfunction, it is not necessary or recommended to take both at the same time. Placement of an implant (prosthesis) in the penis. Vascular reconstruction surgery to improve blood flow to or reduce blood leakage from the penis and surrounding structures. This procedure works. The most common erectile dysfunction pill is Viagra, and the next most common is Cialis. Both medications are phosphodiesterase type 5 (PDE5) inhibitors that work by increasing blood flow to the penis. The major difference is that Cialis lasts longer and can be taken daily, giving you erections on demand. Viagra is always taken a few .