"How many of these can I take, how often can I take them. What do I do if this doesn't work and I need something stronger," said Dr. Jane Schwabe.
Acetaminophen is a generic name of a drug found in many over the counter products, such as Tylenol, as well as prescribed medicine like Percocet or Vicodin.
The drug is generally safe when following doctor's directions, or directions on the label.
However, taking more than recommended, could cause liver failure.
"That's where it's broken down, is in the liver. So, sometimes you can just overwhelm the liver, and the liver stops working well," said Dr. Schwabe.
In 2011, the FDA asked manufacturers to change the amount of acetaminophen in prescription drugs from 500 milligrams per capsule, to 325 milligrams; in hopes to lower the number of people who suffer from liver damage because of the drug.
Those changes had to be completed by the beginning of this year.
"So, they'll get a little less Tylenol. They just have to be aware of what the milligrams say. And, the pharmacy is pretty good about telling you, also, about how much you can have," said Dr. Schwabe.
Taking more than 4,000 milligrams of acetaminophen a day, puts you at risk for possible liver damage.
"I've seen 3,200 milligrams, I've even seen as low as 2,800 milligrams," said Anne Barr.
If you're prescribed a painkiller that contains acetaminophen, and the pain continues after you've taken the recommended dosage, there are other options besides Tylenol.
"Ibuprofen, and Aleve might be OK. But, those can also cause bleeding risks," said Barr.
Doctors and pharmacists said it's important to consult with a doctor before taking any medicine outside of what's prescribed.
"If that's not enough pain relief for them, then they need to contact their prescriber," said Barr.
"Have that talk with your doctor before you go home, so that you know, really, what's best for your particular body," said Dr. Schwabe.
A recent survey shows Tylenol is the most popular painkiller in the united states.
Americans take more than 8 billion pills of Tylenol each year.