Tylenol Extra Strength typically starts to work within 30 to 45 minutes after ingestion when taken on an empty stomach. The pain relief effect generally lasts about 4 to 6 hours. Some rapid-release formulations of Tylenol may work faster, in about 15 to 20 minutes, but the standard Extra Strength tablet usually takes around 30 to 45 minutes to begin providing relief.

Summary of onset and duration:

• Onset of action: about 30 to 45 minutes for regular Extra Strength tablets
• Duration of pain relief: 4 to 6 hours
• Rapid-release gel forms can start working in about 15 to 20 minutes

The effectiveness and timing can vary based on individual metabolism, whether the medication is taken with food, and the specific type of pain being treated. It is advised to follow dosing instructions and not exceed the recommended amount.