IntronA should not be used in: • patients with severe heart disease, • patients with severe kidney or liver disease including that caused by cancer, • patients with epilepsy or other central nervous system problems, • patients with thyroid disease unless it is controlled, • hepatitis patients with liver cirrhosis or who have recently received medicines that affect the immune system, • patients with a history of certain disorders of the immune system, or have had an organ transplant and are taking medicine that suppress immune system • children and adolescents with a history of severe mental illness, particularly severe depression, suicidal thoughts or suicide attempts.