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Riboflavin ˌrī-bə-ˈflā-vən, ˈrī-bə-ˌ

(Vitamin B2)

By Larry E. Johnson, MD, PhD, Associate Professor of Geriatrics and Family and Preventive Medicine;Medical Director, University of Arkansas for Medical Sciences;Central Arkansas Veterans Healthcare System

(See also Overview of Vitamins.)

Riboflavin (vitamin B2) is essential for the processing (metabolism) of carbohydrates (to produce energy) and amino acids. It also helps keep mucous membranes (such as those lining the mouth) healthy. Riboflavin is not toxic.

Good sources of riboflavin include milk, cheese, liver, meat, fish, eggs, and enriched cereals.

Riboflavin Deficiency

  • 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.

Riboflavin deficiency usually occurs with deficiencies of other B vitamins.


Riboflavin deficiency usually results from

  • Not consuming enough protein and calories

The following increase the risk of riboflavin deficiency


Symptoms of riboflavin deficiency may vary. Painful cracks form 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.


  • Physical examination

  • Urine tests

  • Relief of symptoms when riboflavin supplements are taken

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 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.

High doses of riboflavin are taken by mouth until symptoms resolve. If this treatment is ineffective, riboflavin can be given by injection into a muscle. Supplements of other B vitamins are also taken.