Merck Manual

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Riboflavin Deficiency

(Vitamin B2 Deficiency)

By

Larry E. Johnson

, MD, PhD, University of Arkansas for Medical Sciences

Last full review/revision Nov 2020| Content last modified Nov 2020
Click here for the Professional Version

Riboflavin deficiency usually occurs with deficiencies of other B vitamins due to a diet low in vitamins or an absorption disorder.

  • People have painful cracks in the corners of the mouth and on the lips, scaly patches on the head, and a magenta mouth and tongue.

  • The diagnosis is based on symptoms, urine tests, and response to riboflavin supplements.

  • High doses of riboflavin supplements, usually taken by mouth, can correct the deficiency.

The vitamin riboflavin (vitamin B2) is essential for the processing (metabolism) of carbohydrates (to produce energy) and amino acids (the building blocks for proteins). It also helps keep mucous membranes (such as those lining the mouth) healthy. Riboflavin is not toxic, so consuming excess amounts of riboflavin is not a concern. Good sources of riboflavin include milk, cheese, liver, meat, fish, eggs, and enriched cereals.

Causes

Riboflavin deficiency usually results from

  • Not consuming enough meat and fortified cereals and dairy products

The following increase the risk of riboflavin deficiency

Symptoms

Symptoms of riboflavin deficiency may vary. Most commonly, people appear pale and have painful cracks in the corners of the mouth and on the lips. The mouth and tongue are sore, and the tongue may turn magenta.

Red, greasy, scaly (seborrheic) patches may appear around the nose, between the nose and the lips, on the ears and eyelids, and in the genital area.

Diagnosis

  • Physical examination

  • Urine tests

  • Relief of symptoms when riboflavin supplements are taken

Doctors may suspect riboflavin deficiency in people who have typical symptoms and other vitamin B deficiencies. The diagnosis of riboflavin deficiency is based on symptoms and evidence of general undernutrition.

The diagnosis is confirmed by measuring riboflavin excreted in urine or by giving riboflavin supplements, which relieve symptoms if riboflavin deficiency is the cause.

Prevention and Treatment

  • Riboflavin or multivitamin supplements

  • Sometimes riboflavin given by injection

As a preventive measure, people who are undergoing hemodialysis or peritoneal dialysis or who have a malabsorption disorder should take riboflavin supplements or a daily multivitamin.

People who have riboflavin deficiency are given high doses of riboflavin, taken by mouth, until symptoms resolve. Supplements of other B vitamins are also taken.

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