There are four major types of over-the-counter painkillers: aspirin, ibuprofen, naproxen and acetaminophen, but none is inherently stronger than the others. Choose according to the intended use and according to which works best for the individual, says WebMD.
Acetaminophen is the only one of the four that is not classed as a non-steroidal anti-inflammatory drug, or NSAID; it works both for pain relief and as a fever reducer, so it is recommended for children. It also is the least likely to irritate the stomach, so it is often a good choice for those with gastrointestinal issues.
Aspirin and ibuprofen are good for muscle aches, headaches, backaches and other minor, non-chronic pain. Naproxen is recommended for chronic pain from osteoarthritis or other persistent types of pain.
Always consult a physician before using over-the-counter medications for an extended period of time, and follow dosing instructions precisely. It is possible to overdose on these medications, and they do sometimes interact badly with each other and with other drugs.