Acetaminophen can often be used as a safe alternative to other pain relievers, such as aspirin (which increases the risk of Reye's syndrome in children, a rare but potentially fatal condition). However, patients should inform their physician of certain conditions before taking acetaminophen. These include:

• Allergy to acetaminophen or other drugs, or to foods, preservatives or dyes
  
  
• History of liver disease
  
  
• History of alcohol abuse
  
  
• History of kidney disorders or conditions that can damage the kidneys, including systemic lupus erythematosus, sickle cell anemia and diabetes

Patients with phenylketonuria (PKU), a disorder that can cause brain damage and progressive mental retardation, should not use brands of acetaminophen that contain the artificial sweetener aspartame, which can worsen the condition.

Patients with diabetes may find that acetaminophen can cause them to have false results during glucose (blood sugar) tests. Acetaminophen can also interfere with the results of other medical tests. Patients who have scheduled a medical test should inquire in advance about whether they need to refrain from taking acetaminophen for several days before the test.