Riboflavin

Water-soluble vitamin B2

ATC code: A11HA04 (Riboflavin (vitamin B2))

Brand names

Vitamin B2

Mechanism of action

Riboflavin is converted intracellularly to flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These coenzymes participate in oxidative phosphorylation, the Krebs cycle, fatty acid and amino acid metabolism. FAD is required for glutathione synthesis and vitamin K regeneration. The drug colours urine bright yellow as an absorption marker. Body stores are small; daily need 1.1-1.3 mg.

Indications

Migraine prevention

Adjunct

Riboflavin 400 mg/day received Level B (probably effective) in the 2012 /AHS guideline for episodic migraine prevention. Meta-analyses show 1.5-2.5 fewer attacks per month after 3 months of treatment. SEN 2020 lists riboflavin as an option when beta-blockers, topiramate and CGRP antagonists are contraindicated – particularly for patients preferring «natural» therapy and adolescents where topiramate is restricted. Cochrane 2015 acknowledges the positive signal with a favourable safety profile but calls for larger trials. Paediatric data are limited; dose is weight-adjusted. Effect develops slowly – assess at 3 months of uninterrupted use.

Sources

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Fatigue and low energy (supplement marketing)

Not recommended

Riboflavin is vitamin B2. Supplements market it "for energy" and against fatigue, pointing to the vitamin's part in metabolism. In people without a B2 deficiency, riboflavin has shown no clear benefit for tiredness or low energy, and there is no evidence base behind this use. Lasting fatigue usually traces back to poor sleep, anemia, thyroid problems or depression, so finding the cause with a doctor helps more than a vitamin. Riboflavin is harmless in this role, but do not take it instead of treatment with proven benefit, or you may miss the real reason for the fatigue

Sources

Cochrane: Riboflavin for migraine prevention (2015)

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Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMA

Spanish Medicines Information Centre (CIMA)

Label dated: 10/24/2024

FDA / DailyMed

FDA — DailyMed Drug Labels

Label dated: 01/27/2027

Safety

Contraindications

Hypersensitivity to riboflavin (very rare)

Serious adverse effects

Not reported with oral physiological and therapeutic doses

Common adverse effects

Bright-yellow urine discolouration (pharmacological feature, not pathology)
Transient diarrhoea at high doses
Polyuria

PregnancyFDA A

FDA Category A. Riboflavin is required in pregnancy; recommended daily intake 1.4 mg. Migraine-prophylaxis doses (400 mg/day) in pregnancy are poorly studied; AEMPS recommends discussion with a neurologist and a preference for beta-blockers or non-pharmacological measures.

Breastfeeding

Compatible. Hale L1. Riboflavin passes into breast milk; infant levels reflect maternal diet. Physiological and prophylactic doses are safe.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Riboflavin used for?

Riboflavin is evaluated for the following indications with varying evidence strength: Migraine prevention (evidence tier B), Fatigue and low energy (supplement marketing) (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Riboflavin?

Common side effects of Riboflavin (≥ 1 in 100): Bright-yellow urine discolouration (pharmacological feature, not pathology), Transient diarrhoea at high doses, Polyuria. See the Safety section for uncommon and serious reactions.

Is Riboflavin safe during pregnancy?

FDA category A. FDA Category A. Riboflavin is required in pregnancy; recommended daily intake 1.4 mg. Migraine-prophylaxis doses (400 mg/day) in pregnancy are poorly studied; AEMPS recommends discussion with a neurologist and a preference for beta-blockers or non-pharmacological measures.

Is Riboflavin compatible with breastfeeding?

Compatible. Hale L1. Riboflavin passes into breast milk; infant levels reflect maternal diet. Physiological and prophylactic doses are safe.

Who should not take Riboflavin?

Riboflavin is contraindicated in: Hypersensitivity to riboflavin (very rare). Full list in the Safety section.

Mechanism of action

Indications

Migraine prevention

Adjunct

Sources

Safety

Contraindications

Hypersensitivity to riboflavin (very rare)

Serious adverse effects

Not reported with oral physiological and therapeutic doses

Common adverse effects

Bright-yellow urine discolouration (pharmacological feature, not pathology)
Transient diarrhoea at high doses
Polyuria

PregnancyFDA A

Breastfeeding

Compatible. Hale L1. Riboflavin passes into breast milk; infant levels reflect maternal diet. Physiological and prophylactic doses are safe.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Riboflavin used for?

What are the side effects of Riboflavin?

Is Riboflavin safe during pregnancy?

Is Riboflavin compatible with breastfeeding?

Compatible. Hale L1. Riboflavin passes into breast milk; infant levels reflect maternal diet. Physiological and prophylactic doses are safe.

Who should not take Riboflavin?

Riboflavin is contraindicated in: Hypersensitivity to riboflavin (very rare). Full list in the Safety section.