What Is the Active Ingredient in Tylenol®?

The active ingredient in Tylenol® is acetaminophen. This is true only for the basic and extra-strength pain relievers manufactured by the company and not for specialty products such as sleep aids and sinus treatments. Acetaminophen is effective in treating a wide range of pain conditions including headache, joint pain, and fever. The medication, which is sold under many other brand names, has potentially serious side effects with long-term use.

Acetaminophen is a pain reliever that belongs to the medicinal classes of analgesics and antipyretics. The exact mechanism of action is unknown, but is thought to involve inhibition of the enzyme cyclooxygenase, specifically the enzymes located within the central nervous system. This enzyme, when uninhibited, can lead to an overproduction of prostaglandins that are helpful in regulated quantities, but cause pain, inflammation, or fever when present in abundance.

As an active ingredient in Tylenol®, acetaminophen is available in capsule, tablet, and suspension dosage forms. Dosage may be standard, extended-release, or fast-acting, depending upon the formulation. Higher short-term doses may be advised by a doctor in cases of a moderate injury, such as a sprained wrist, or when a patient is running a high fever. Suspension dosing is primarily done for small children who may have difficulty swallowing tablets and those whom the dosage must be kept very low to prevent harmful side effects or toxicity.

There are potential drug interactions for acetaminophen. Certain blood thinners and seizure medications can create adverse reactions when taken concurrently with this medication. It’s not advised to drink alcohol in excess while maintaining a steady acetaminophen dosage.

Potential side effects of this active ingredient in Tylenol® include hives, swelling, and rash. Presentation of any side effect should result in cessation of dosage as it may indicate an allergy. Long-term or high-dose use of acetaminophen may cause more serious of side effects. Liver damage to a severity requiring transplant, is possible with abuse of this medication.

Though acetaminophen is the active ingredient in Tylenol®, it also appears as an active ingredient in may other products, so it's important to pay close attention to ingredients lists on the label or prescription information. Acetaminophen is also called APAP, especially when it is blended with the pain killer hydrocodone, and paracetamol. Name brands also exist other than Tylenol&reg that sell a basic pain reliever with this ingredient.