Pain is the main complaint for about 40 percent of patients visiting primary-care doctors with roughly half of the people with chronic or recurrent pain failing to get adequate relief. In many ways pain remains a medical mystery, but here’s what to do for occasional, severe, and recurrent pain:

Self assess. First, assess how bad the pain is. Rate it on a scale of 0 (no pain) to 10 (the worst pain you could imagine). For pain that you rate 5 or less, start by self-treating with nondrug measures. For example, use heat to help ease back pain or cramps. You can also use over-the-counter pain relievers, which typically suffice for this level of pain.

How to choose an over-the-counter. Choose a drug based on the type of pain and your risk factors. Acetaminophen (Tylenol or generic) is often a good option. At recommended doses it's reasonably safe and effective for most people. People who drink heavily or have a liver disorder should avoid acetaminophen, since it's toxic to the organ. Ibuprofen and naproxen are often good over-the-counter choices if acetaminophen isn't enough. They not only ease pain but also quell inflammation. Both drugs are probably safer than aspirin, which poses a higher risk of bleeding. And while long-term use of any NSAID poses serious gastrointestinal and possibly coronary risks, the short-term use of recommended doses is generally safe for most people who don’t have heart, kidney, or stomach problems.

Severe-pain solutions. If you rate your pain at 6 or higher, it doesn’t improve with nondrug steps and OTC drugs, or it lasts longer than a few days, see your doctor. He or she might suggest a prescription NSAID, because a different or stronger formulation may yield additional relief. Another approach can be a prescription opioid such as oxycodone (Oxycontin and generic). You or your doctor might resist using such drugs because of addiction concerns. But physical dependence typically requires several weeks of use, and psychological dependence in patients with acute or severe pain is unlikely because they rarely experience euphoria from the drugs.

Medications that pair an opioid with acetaminophen, aspirin, or ibuprofen may be an even better choice. Those can provide greater relief, since the two ingredients work in different ways, and they reduce the risk of side effects because the combination permits smaller doses of each.

Recurrent pain. Even when the pain is relatively mild, chronic or recurrent pain from arthritis, headaches, or other sources can seriously interfere with everyday activities. Since chronic pain often ebbs and flows, rating your discomfort on the 0 to 10 pain scale can help you decide, day to day, how to manage the problem.

For more information, see Consumer Reports’ Best Buy Drug report on opioids.