Tylenol's primary active ingredient is acetaminophen (also known as paracetamol outside the U.S.). Acetaminophen is a widely used analgesic (pain reliever) and antipyretic (fever reducer). Tylenol products may also contain additional ingredients depending on the formulation, but acetaminophen is the main component that provides pain and fever relief.
Acetaminophen works by elevating the body's overall pain threshold and helping reduce fever by affecting the brain's temperature regulation center. Unlike NSAIDs (like ibuprofen or aspirin), acetaminophen is not an anti-inflammatory drug.
In summary, Tylenol essentially contains acetaminophen as the key ingredient for relieving minor aches, pains, and fever. Other formulations under the Tylenol brand may include ingredients like caffeine or antihistamines for specific uses, but the core ingredient is acetaminophen.