Hi Missing Buddy,
Dr Justin Harmon wrote an article here about the Caverject and penile injections and how they work. He also wrote another article about side effects. You can read that article here.
I's possible your husband might have some issues that he should discuss with his doctor. Online sites like HealthCentral are wonderful for gathering the information you need to be able to ask all the right questions, however they can not take the place of your doctor's advice.
Hope this helps! Take care and stay in touch, let us know how you are doing!Vicki M