There are many medications that are used to treat deep somatic pain. Some of these, like aspirin and ibuprofen, are over-the-counter medications. You do not need a prescription to buy them, and they are usually effective for relieving less severe pain. Others, like morphine, are used to treat severe pain, and it is necessary to have a prescription from your doctor to buy them. Most painkillers work by interfering with pain signals going to the brain. Some medications, like ibuprofen, also help relieve pain by reducing the redness and swelling that often comes with an injury.