Acetaminophen is a medication that relieves mild to moderate pain and reduces fever. It is often used by patients who cannot tolerate anti-inflammatory drugs such as aspirin.

Unlike those drugs, acetaminophen does not significantly reduce the stiffness, redness and inflammation often associated with diseases such as arthritis. Yet it can help treat a wide range of conditions from headaches to whiplash to back pain.

Scientists are unsure exactly how acetaminophen works to relieve pain. However, it is believed that the drug may increase a patient’s pain threshold by blocking pain centers in the central nervous system. In some cases, acetaminophen therapy is combined with opioids or other drugs. This combination can enhance the painkilling effect of the medication.

Acetaminophen is available as a standard tablet, chewable tablet, capsule, liquid, drop, suppository or granule that can be dissolved in water. Dosage levels are adjusted for age to limit the chance of side effects, which include anemia, skin rash and other conditions.

Though acetaminophen is often a safe and effective painkiller, it can be dangerous when not taken at the proper dosage or if a person has certain medical conditions. Overdose is a leading cause of liver failure. Patients who have concerns, such as those who suspect they may be allergic, have a history of alcohol abuse, or have had liver or kidney disorders, should first talk with a physician before taking acetaminophen.