When did tylenol start?

When did Tylenol (acetaminophen) first come out?

Tylenol began in the early 1950s as a brand of the pain reliever acetaminophen.

Which year is Tylenol’s “start” commonly associated with?

The Tylenol brand is most commonly associated with 1955, when McNeil (the company that marketed Tylenol) introduced it widely in the United States.

Why do people sometimes give different years?

Dates can vary depending on whether someone means:
- when acetaminophen was first developed/approved as a drug, or
- when the Tylenol brand was launched and promoted to the public.

Because your question asks when Tylenol started, the commonly cited answer is 1955.

Sources

If you want, tell me whether you mean the first launch year in the US (brand introduction) or when acetaminophen itself first received regulatory approval, and I can narrow it to the exact event and date.