Acetaminophen (aka APAP, paracetamol or Tylenol® — I’m mostly using APAP here) is a medication used to treat pain and fever. Recently, it has been in the news for its potential to harm our bodies because, like everything, it can be toxic in the wrong dose.

While acetaminophen has been used safely for years, overdoses of this medication can cause permanent liver damage and liver failure. The dose it takes to cause liver damage is well understood for both adults and children.

Liver damage can occur from acute (one-time dose) or chronic (repeated doses over days) overdosing. Acute overdose (a single, one-time large dose) can cause liver damage, but the signs of liver damage are delayed 1-2 days. Once the signs of liver damage start (nausea, vomiting, abdominal pain), treatment is difficult.

Chronic overdose (large amounts over days) can also cause liver damage. Signs of damage can be abdominal pain, nausea, vomiting and yellow skin. Chronic overdose is more common from people taking APAP from more than one product (often unknowingly).

APAP is the most common medication found in over-the-counter medications–it is often in cough and cold medications and sleeping medications. It is also frequently part of prescription pain medications. If you aren’t aware of this added ingredient and take Tylenol or APAP in other forms along with your cough medicine, sleep aid or painkiller, you could unintentionally overdose on APAP. Unfortunately the physical damage, especially to the liver, caused by too much APAP cannot be felt immediately. You won’t know about the irreversible harm until you are getting severe symptoms.

It can be very confusing to walk into a pharmacy and see so many over-the-counter medicines to treat your symptoms. When selecting the product you want, carefully read the labels to know the ingredients inside each bottle. That’s more important than what symptoms the bottle says the medicine will treat. And ask your physician, pharmacist or local poison center for more information if you have any questions about dosing, combining drugs and using APAP medicines.

Call the toll-free national hotline at 1-800-222-1222 to reach your local poison center. If you live in Arizona outside of Maricopa County, this number will get you to our experts at the Arizona Poison and Drug Information Center in Tucson. Check out our Web site for more information.