For decades, Tylenol has enjoyed a near-universal reputation for safety. However, a recent analysis has indicated that recent negative attention over the risk of Tylenol liver damage has begun to change public opinion of the drug.

The active ingredient in Tylenol is a drug called acetaminophen. When the body breaks this drug down, it converts it into smaller molecules called secondary metabolites. This is how the body rids itself of many drugs, and keeps many toxic substances from building up in the body.

However, in the case of acetaminophen, the secondary metabolites are more toxic than acetaminophen itself. Under normal circumstances, these secondary metabolites are produced slowly enough or in such small amounts that the body can break them down further or excrete them.

However, in some individuals, metabolism works differently and in ways that produces slightly more toxic secondary metabolites, or produces them quicker. This means that some individuals could suffer liver damage, even at the recommended dose of Tylenol.

This has led to renewed scrutiny and legal action against the makers of Tylenol and other acetaminophen-based drugs.

A New York market research group, Brand Keys, recently published its yearly Customer Loyalty Engagement Index for 2014. The group used statistical analysis to quantify how loyal customers were to use different brands of over-the-counter pain medication.

The Brand Keys report cites problems with recalls and distribution as contributing factors, but states that increased scrutiny over the risk of Tylenol liver damage is a major factor in the drug’s declining popularity.

This includes the fact that the U.S. Food and Drug Administration (FDA) released a warning in January, advising consumers and medical professionals to avoid using more than 335 mg of acetaminophen in a single dose.

The FDA’s statement indicated that there was no evidence that the benefits of additional acetaminophen beyond this dosage outweighed the risk of liver damage. The warning states that inadvertent overdose of acetaminophen could lead to liver failure and death. This has translated to Tylenol losing more than half of its market share between 2009 and 2012.

Consumers have filed Tylenol lawsuits against the makers of Tylenol and other acetaminophen-based drugs, alleging that drug makers have not done enough to protect the public from the risk of liver damage.

To deal with the deluge of similar Tylenol liver damage lawsuits, the legal system has combined these Tylenol lawsuits in a type of coordinated legal action called a multidistrict litigation or MDL. MDLs are designed to help streamline the legal system by combining similar lawsuits into a single MDL.

The Tylenol Liver Damage MDL is In re Tylenol (Acetaminophen) Marketing, Sales Practices, and Products Liability Litigation, MDL No. 2436, in the U.S. District Court for the Eastern District of Pennsylvania.