Penile Injections are another option for post prostatectomy men in order to restore sexual performance. Injectable medications are typically prostaglandin E1, or a combination of papaverine and phenotolamine. The best option will be determined by your physician. This treatment option has proven successful 85-95% of the time for men post prostatectomy surgery. Penile injection usually take effect in 5-20 minutes. These products should not be used more than 3 times per week and must ensure 24 hours between injections. Some men experience some temporary burning at injection site. In order to prevent scaring which could result in un-natural curving of the penis, rotate injection site. For example, after injecting into the left corpus cavernosum, next time inject the right side, etc. For erections lasting more than 4 hours, you must seek immediate medical attention. An overly engorged penis for extended period of time could result in permanent damage to the penis.