Case 27 – Looking a Little Flush…

Case #27: Looking a Little Flush…
Author: Jami Hickey, MD
Peer Reviewer: Michael Wahl, MD

A 26 year old male presents to the ED with a chief complaint of a diffuse rash. The rash started 30 minutes prior to arrival and became very diffuse, pruiritic, and warm. He denies throat or tongue swelling, shortness of breath, or a prior history of similar rash.

Vitals: Temp: 98.7, BP: 100/65, HR: 95, RR: 20, O2 Sat: 100% on RA

On examination, he appears flushed diffusely on his face, neck and chest, and is mildly diaphoretic.

On further prompting, he states that he was supposed to have a urine drug screen tomorrow for a new job. He smokes marijuana and a friend told him to take a “vitamin” to try to make sure his drug screen was negative. The patient does not remember the name.

What vitamin is probably responsible for the patient’s symptoms?
Niacin (Vitamin B3). Niacin is touted on the Internet as a method of evading drug detection on a routine urine drug screen, but there is no evidence that it actually works.
How does this vitamin produce the above effects?
Niacin induces Histamine release, which causes the pruritic flushing, as described above. When used for therapeutic reasons (i.e. dyslipidemia), this side effect can be mitigated by pre-treating with Aspirin prior to each dose.
What is the treatment for this toxicity?
Treatment is predominately supportive with oral diphenhydramine, as needed for itching.  Symptoms usually resolve within an hour, although they will likely recur with repeat dosing until the patient develops a tolerance, which may take 2-3 weeks. Many patients who take niacin for dyslipidemia discontinue use due to the severity of the flushing.
What adverse effects can be seen at higher doses and what is the treatment?
With higher concentrations, patients can develop nausea, abdominal cramping, diarrhea, headaches, transaminitis, and impaired glucose tolerance.  Again, supportive care is all that is needed, as all of the symptoms resolve within weeks of stopping the medication.
What other vitamins are known to cause significant toxicity?
Vitamin A – Blurred vision, orange skin changes, anorexia, bone pain/fractures, and liver failure
Vitamin B6 – Peripheral neuropathy
Vitamin C – Gout, nephrolithiasis, renal failure
Vitamin D – Hypercalcemia
Vitamin K – Hemolytic anemia (infants), kernicterus (infants), liver damage, and renal failure
Note: IV Vitamin K can cause potentially fatal hypotension and anaphylactoid reactions when given too rapidly.


Alsheikh-Ali AA, Karas RH. The safety of niacin in the US Food and Drug Administration adverse event reporting database. Am J Cardiol. 2008 Apr 17;101(8A):9B-13B.

Daul AM, Beuhler MC. Niacin toxicity resulting from urine drug test evasion. J Emerg Med. 2011 Sep;41(3):e65-8.

Return to Case List