Are painkillers 100% forceful surrounded by terminally in poor health patients?

Thanks. This is for my debate speech on euthanasia.Are painkillers 100% forceful surrounded by terminally in poor health patients?
No they are not, especially if that terminally ill lenient has cancer. Once cancer spreads and go into the bones, not even morphine will stop the pain 100%. My grandmother died of lymphoma, and within the last days of her existence when she was surrounded by hospice, they were giving her mega doses of morphine and it wasn't helping her, adjectives it did was allow her to sleep rather, but not much. Fortunately she died a week later ( not that I am contented about her passing, we knew it be coming)- so she didn't suffer too much like some folks do.
They might be if we legalized a combination of heroin and marijuana for these poor people.