Drugs can harm the liver in a variety of ways. Some medications harm the liver directly, while the liver converts others into compounds that directly or indirectly damage the liver. (This may seem odd given the liver's critical role in converting hazardous substances to harmless compounds, yet it happens.) Dose-dependent toxicity, idiosyncratic toxicity, and medication allergy are the three forms of liver toxicity. If enough of a medicine that causes dose-dependent toxicity is consumed, it can cause liver disease in most persons. Overdosing on acetaminophen (Tylenol) is the most common cause of dose-dependent toxicity (discussed later in this article.).