Acetaminophen is a fever reducer and a pain reliever. It's not fully understood how this drug works. Acetaminophen doesn't decrease swelling or inflammation. Instead, it likely changes the way your body senses pain.

How quickly does acetaminophen reduce fever?

Two hours after acetaminophen is taken, it will usually reduce the fever by 2 to 3 degrees F. Repeated does of the drug are often necessary because the fever will go up and down until the illness runs its course.

Which is better for fever acetaminophen or ibuprofen?

Official Answer. Acetaminophen is only effective at relieving pain and fever, while ibuprofen relieves inflammation in addition to pain and fever. Other key differences: Some research suggests NSAIDs such as ibuprofen are more effective than acetaminophen at relieving pain.