According to Drugs.com, the active ingredient of Advil is ibuprofen, not acetaminophen. Advil is a non-steroidal anti-inflammatory drug used as an analgesic to help with inflammation and pain.
Advil should only be taken as directed by a physician or by what it states on the label if bought over the counter, and it should not be taken by pregnant women in their third trimester. Side effects can include stomach pain, heartburn, gas, bloating, diarrhea and a decrease in urine. Serious side effects may include allergic reactions, vomiting, wheezing, seizures, chest tightness, heart problems or intestinal bleeding. When taken as directed, side effects are typically mild.