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Cheating on a Drug Test Can Have Toxic Results


How safe is the use of high doses of niacin to foil urine drug screening tests?

Niacin (vitamin B3) has been used as traditional therapy to treat vitamin deficiency and elevated lipids1 and as an alternative agent to "promote metabolism."2 In any setting, niacin is associated with a host of adverse effects, including flushing, pruritus, nausea and vomiting, hepatotoxicity, insulin resistance, and cystic macular edema.

More recently, niacin has found a new "unapproved" and potentially dangerous indication: covering up illicit drug use. In fact, "Googling" the topics "pass urine drug test" and "niacin" yields about 85,000 results.2 Although niacin's efficacy in this regard is probably no more than urban legend, the consequences of this novel use are reaching medical attention.


A recent report discussed the adverse effects of niacin in 4 patients who had used this agent to clear their urine of illicit drugs (such as cocaine, "ecstasy," and marijuana) before employment physical examinations.2 Two of these patients had life-threatening complications. Although the more typical side effects of niacin were apparent in most of the patients, newer or more exaggerated disturbances were also evident. These were an anion gap metabolic acidemia, hypoglycemia, coagulopathy, a striking neutrophilia, and a prolongation of the QTc interval. Toxicology studies at the time of presentation were negative for ingestion of other drugs.


As a "lapsed" nephrologist who is now a primary care physician, I am fascinated by the acidemia. For years, the differential diagnosis of metabolic acidemia has been taught with the mnemonic MUDPILES. The letters originally stood for Methanol, Uremia, Diabetic ketoacidosis, Paraldehyde, Isoniazid (INH), Lactic acid, Ethylene glycol (antifreeze), and Salicylic acid (aspirin). However, some of these agents (particularly paraldehyde) are neither available nor commonly taken in doses high enough to cause acidemia (for example, INH). A contemporary revision to MUDPILES is in order.

Recent changes in therapy and illicit drug use have supplanted the old standbys associated with metabolic acidemia. The new P and I are Propylene glycol and Ingestions like ecstasy, cocaine, and now niacin.3 Propylene glycol is added to parenteral solutions of lorazepam, which is then given in large doses for alcohol withdrawal syndrome. Propylene glycol is metabolized to lactic acid and can cause both an anion gap acidemia and hyperosmolality.

Times have changed. The discovery of metabolic acidemia with an anion gap should now alert clinicians to the possibility of illicit drug use or an attempted cover-up of that use.




Guyton JR, Bays HE. Safety considerations with niacin therapy.

Am J Cardiol

. 2007;99(suppl):22C-31C.


Mittal MK, Florin T, Perrone J, et al. Toxicity from the use of niacin to beat urine drug screening.

Ann Emerg Med.

2007 Apr 4; [Epub ahead of print]. Accessed May 16, 2007.


Whittier WL, Rutecki GW. Primer on clinical acid-base problem solving.

Dis Mon.



• Banker D, Whittier FC, Rutecki GW. Acid-base disturbances: 5 rules that can simplify diagnosis.



• Banker D, Whittier FC, Rutecki GW. Acid-base problem solving.



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