Have been using trimix now for a few months and I heartily recommend it to anyone with ED of any nature. As mentioned above the injection is painless and it is just the thought of what you are doing the first few times that are any sort of stumbling block. One also must gauge the dosage carefully as mentioned above and be aware that the product has a very limited shelf life although that can be extended by keeping the product frozen in freezer and just thawing enough each time that it is required. You also have to gauge the increase in dosage as the product ages. I have found that getting to the right injection site also affects the time that it lasts. Depending on dosage etc it is very easy to go anywhere from 1 hour to more than 4 hours with no ill affects.
Talk to your urologist. They can be quite forthcoming in other methods as well if your ED is severe.