They also work differently. For most people, OTC medicines are all they need to relieve occasional pain. If an OTC medicine doesn't help your pain or fever, call your doctor. Or if you've been taking an OTC medicine for more than a couple of days for fever or a couple of weeks for pain, call your doctor. These may be signs that you have a more serious problem or need a prescription medicine.
All medicines can have side effects.
However, side effects are usually not a problem for healthy people who only use pain relievers once in a while. Side effects can be a concern for people who regularly use pain relievers or have health problems. If you have questions about side effects, talk to your doctor. Acetaminophen may cause liver or kidney damage in people who take very high doses or who frequently drink alcohol. The following advice is for healthy adults who only need a pain reliever once in a while.