After you swallow or drink the pain reliever it doesn’t go directly to where you’re feeling the pain. According to kidsheath.org “pain reliever’s work with your cells, your body’s nerve endings, your nervous system, and your brain to keep you from feeling the pain”.
According to kidsheath.org when cells in your body are injured or damaged, they release a chemical called prostaglandin. This chemical is from your nerves. When the nerves in your body kind of explode they release the chemical called prostaglandin. The way that a pain reliever works, it prevents cells that are ill and causing you pain from making and releasing a chemical called prostaglandin.
As you can see, pain helps you realize that something is wrong. The pain reliever will work with your brain and cells to keep you from feeling the pain. If reading this gave you a head ache go get yourself a pain reliever.
References: http://kidshealth.org Mary L. Gavin, Medical Doctor