Can I take tylenol (acetaminophen) if I have a fatty liver?

Liver function? You can have a fatty liver and still have normal liver function, and then it's fine to use tylenol (acetaminophen). However, you can also have a fatty liver and crappy liver function, then tylenol (acetaminophen) may not be best option for you. So you need to know more than just fatty liver - how is it working?
No ,avoid if possibl. Fatty liver progresses slowly to cirrhosis leading o end stage liver failure. Its progress can slowed for years by proper care, diet, avoiding alcohol , drugs etc. Tylenol (acetaminophen) in some can cause severe centri-lobular hepatic necrosis. So avoid it.