A nurse is teaching a class about using niacin to reduce LDL cholesterol. The nurse should include in the teaching that which of the following conditions is a contraindication for receiving this medication?

Niacin (nicotinic acid) is a B-vitamin used in high doses to lower LDL and triglycerides while raising HDL cholesterol. Active liver disease is an absolute contraindication to niacin therapy because niacin is hepatotoxic at therapeutic doses and is extensively metabolized by the liver. Prescribing niacin to a client with pre-existing hepatic dysfunction risks severe liver damage, including fulminant hepatic failure. Liver function tests must be monitored regularly in clients receiving niacin. High blood pressure is not a contraindication; niacin may actually cause flushing and vasodilation that transiently lowers blood pressure. Hyperthyroidism is not a contraindication, although niacin can slightly alter thyroid function tests; it is not listed as a contraindication in standard references. Asthma is not a contraindication, though some sources note that flushing can occasionally be uncomfortable; asthma itself does not preclude use. The key teaching point is that any pre-existing liver condition rules out niacin as a treatment option, and clients should be counseled to avoid alcohol and hepatotoxic substances while on this medication. Recognizing contraindications versus precautions is a common exam focus.