I've heard people say that Tylenol is safe but many of us think that its safe maybe because its easily available but, what are the risks associated with Tylenol (acetaminophen/paracetamol)?
The main risk of Tylenol (aka acetaminophen/paracetamol) is liver damage, as this article from the FDA advises:
This drug is generally considered safe when used according to the directions on its labeling. But taking more than the recommended amount can cause liver damage, ranging from abnormalities in liver function blood tests, to acute liver failure, and even death.
Liver damage may take awhile to develop:
You may not notice the signs and symptoms of liver damage right away because they take time to appear. Or, you may mistake early symptoms of liver damage (for example, loss of appetite, nausea, and vomiting) for something else, like the flu. Liver damage can develop into liver failure or death over several days.
RxList recommends the maximum dosage as 3250 mg (3.250 grams) per day, which is pretty much in line with everything else I've read.
As I said in comments, nearly all drugs have some sort of side effects. That said, acetaminophen appears to be safe when taken as directed. While taking acetaminophen, you need to pay close attention to any other medications you may be taking that may include acetaminophen, such as cough and cold remedies. You also need to be careful that you're not taxing your liver with other things like alcohol.
Edit: In response to comments:
The aforementioned link to RxList also advises that up to 4 grams per day may be taken under the care of a healthcare professional, who will, presumably, monitor your hepatic function. Do not take this dose unless you are under the care of said professional! This statement in no way endorses this dosage.