Riboflavin

Evidence Level
Strong
8 Clinical Trials
8 Documented Benefits
4/5 Evidence Score

Riboflavin (vitamin B2) is an essential water-soluble vitamin central to energy production and to recycling antioxidants such as glutathione. It also helps activate other B vitamins, including B6 and folate. Adequate amounts are easily obtained from dairy, eggs, lean meats, and fortified grains, so deficiency is uncommon. Supplements are widely sold for energy, but taking extra riboflavin has not been shown to raise energy in someone who already gets enough; riboflavin is a cofactor the body requires, not a stimulant. At a much higher dose of around 400 mg per day it has been studied as a migraine preventive in adults under medical care. Riboflavin is considered very safe because excess is excreted, which harmlessly turns urine bright yellow, a normal and expected effect rather than a cause for concern.

Studied Dose 1.1 to 1.3 mg/day (RDA). Migraine research dose: 400 mg/day in adults, roughly 300 times the daily requirement, studied for a diagnosed condition and appropriate only under a doctor's supervision. A trial in children at 50 mg/day found no benefit. Supplements commonly contain 10 to 50 mg/day, but no cited study shows a specific benefit at that level beyond meeting the RDA.
Active Compound Vitamin B2 (Riboflavin / R-5-P)
Deficiency information View details

Riboflavin (vitamin B2) deficiency, also called ariboflavinosis, is extremely rare in the US but can occur in people with very limited diets, alcohol use disorder, or specific genetic disorders. Riboflavin deficiency rarely occurs alone — it usually appears alongside deficiencies of other B vitamins.

Common symptoms

  • Cracks at the corners of the mouth (angular stomatitis)
  • Swollen, cracked lips (cheilosis)
  • Sore throat
  • Magenta-colored, swollen tongue (glossitis)
  • Skin disorders, including seborrheic dermatitis around the nose and mouth
  • Itchy, red, or bloodshot eyes; sensitivity to light
  • Hair loss
  • Fatigue from associated normocytic anemia

At-risk groups

  • People with alcohol use disorder (poor intake plus impaired absorption)
  • People with very limited diets or anorexia
  • Strict vegans avoiding all dairy and fortified foods (dairy is a major source)
  • Pregnant and breastfeeding women with poor intake
  • Adolescents during growth spurts who skip breakfast
  • Athletes with extremely high energy expenditure and poor diet
  • People with malabsorption conditions
  • People with rare inherited disorders affecting riboflavin transport
When to see a doctor: Persistent cracks at the corners of the mouth, recurrent sore throat with swollen tongue, or seborrheic dermatitis that doesn't respond to standard treatment may warrant evaluation for B-vitamin deficiencies. A dietitian or doctor can assess intake and order targeted testing.

Benefits

Studied for Migraine Prevention in Adults

In a 1998 randomized, placebo-controlled trial in 55 adults with recurrent migraines, riboflavin at 400 mg per day for 3 months lowered attack frequency and headache days compared with placebo: 59 percent of the riboflavin group improved meaningfully versus 15 percent on placebo. A 2017 systematic review of 11 trials found this adult benefit fairly consistent but the overall picture mixed, especially in children. The one pediatric trial cited here, a crossover study in 42 children aged 6 to 13, used 50 mg per day and missed its main goal: no reduction in migraine attacks versus placebo. So the effect appears dose dependent, and 400 mg per day is a medical dose for a diagnosed condition that belongs under a doctor's care rather than general self-treatment.

Energy Metabolism

Riboflavin is a precursor to flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), coenzymes critical for carbohydrate, protein, and fat metabolism. These coenzymes are needed for cells to turn food into usable energy. That is a requirement, not a boost: correcting a genuine shortfall can help, but none of the studies cited on this page show that extra riboflavin raises energy levels in someone whose intake is already adequate.

Cardiovascular Health

Research in people who carry two copies of the MTHFR 677T gene variant has looked at riboflavin, around 1.6 mg per day, for blood pressure and for homocysteine, a blood marker. None of the four studies cited on this page tested this, so the specific numbers cannot be checked here and it should be treated as an area of ongoing research rather than a proven benefit. Blood pressure and homocysteine readings are measurements, not proof that heart problems were prevented.

Eye Health

Riboflavin is part of the enzyme glutathione reductase, which keeps the antioxidant glutathione in its active form, and severe deficiency can cause sore, itchy, light-sensitive eyes. None of the four studies cited on this page tested riboflavin for cataracts or for vision, so a cataract-prevention benefit should not be assumed from the biochemistry alone.

Medical Use in Rare Inherited Metabolic Disorders

Doctors use very high doses of riboflavin to manage rare inherited metabolic conditions such as multiple acyl-CoA dehydrogenase deficiency, where a specific gene defect impairs how the body uses fats for fuel. This is medical care for a diagnosed genetic disease, prescribed and monitored by a specialist. It is not a reason for a healthy person to take a supplement, and none of the four studies cited on this page examined it.

Skin and Mucous Membrane Health

Riboflavin deficiency can cause cheilosis (cracked lips), angular stomatitis, and dermatitis. Getting enough riboflavin from food or a basic supplement prevents these deficiency signs. Nothing cited here shows that taking more than you need further improves skin or lips in a person who is not deficient.

Red Blood Cell Production

Riboflavin plays a role in how the body handles iron and in red blood cell production, and deficiency can contribute to anemia. That comes from a review of riboflavin deficiency, not from a supplement trial: no study cited here tested riboflavin supplements as a treatment or preventive for anemia in people with adequate intake.

Antioxidant Support

As part of the enzyme glutathione reductase, riboflavin helps recycle glutathione, one of the body's main antioxidants. That is established biochemistry. Whether riboflavin supplements reduce oxidative damage, or affect eye or brain conditions, was not tested in any of the four studies cited on this page.

Mechanism of action

1

Coenzyme Role

Riboflavin is converted into FMN and FAD, which serve as coenzymes in redox reactions. These coenzymes act as electron carriers in enzymatic reactions, facilitating the transfer of electrons in metabolic pathways.

2

Energy Metabolism

FMN and FAD are essential for the function of flavoproteins, which are involved in the metabolism of carbohydrates, fats, and proteins. They participate in the electron transport chain, contributing to ATP production via oxidative phosphorylation.

3

Enzyme Cofactor

FAD and FMN are cofactors for enzymes like glutathione reductase, which maintains reduced glutathione levels for antioxidant defense, and succinate dehydrogenase, a key enzyme in the citric acid cycle.

4

Antioxidant Support

By supporting glutathione reductase, riboflavin indirectly protects cells from oxidative stress by maintaining the antioxidant glutathione in its reduced form.

5

Other Functions

Riboflavin-dependent enzymes are involved in the metabolism of other B vitamins (e.g., vitamin B6 and folate) and the synthesis of niacin from tryptophan.

Clinical trials

1
Riboflavin for Migraine Prophylaxis — Schoenen Clinical Trial

Randomized, double-blind, placebo-controlled trial in 55 adults with recurrent migraines receiving riboflavin (400 mg/day) vs placebo for 3 months. Outcomes: migraine frequency, duration, intensity. (Neurology)

55 adults with recurrent migraines.

Riboflavin cut the number of migraine attacks and headache days compared with placebo: 59 percent of the riboflavin group improved meaningfully versus 15 percent on placebo. Limitations worth knowing: this is a single trial, only 55 people, only 3 months long, and the 400 mg daily dose is roughly 300 times the daily requirement, so it is a medical dose rather than a nutritional one. Side effects were few, and the bright yellow urine riboflavin causes is harmless.

2
Riboflavin for Migraine in Children (Bruijn 2010): No Benefit

Randomized, double-blind, placebo-controlled crossover trial in 42 children aged 6 to 13 with migraine, taking 50 mg/day riboflavin or placebo for 16 weeks in each arm. (Bruijn et al. 2010, Cephalalgia; PMID 20974610)

42 children aged 6 to 13 with migraine.

This trial did not show a benefit. Its main goal was fewer migraine attacks, and 50 mg per day was no better than placebo (P=0.44). The authors concluded plainly that there is no evidence 50 mg of riboflavin prevents migraine attacks in children. One secondary measure, tension-type and in-between headache days, did reach significance (P=0.04), but a secondary result does not rescue a failed main outcome. Read alongside the adult trial, the effect looks dose dependent: 400 mg helped adults, 50 mg did not help children.

3
Riboflavin as Medication Adherence Biomarker — Trial

2-year clinical trial assessing riboflavin as a biomarker for medication adherence in clinical trials. Outcomes: urinary riboflavin as proxy for compliance.

Trial participants.

Because riboflavin shows up visibly in urine, researchers have used it to check whether study participants actually took their pills. This is a research technique, not a health benefit, and it is not one of the four studies cited on this page, so its details cannot be verified here.

4
Riboflavin as Surrogate Marker for BCRP Activity — Pilot

Pilot study evaluating riboflavin as endogenous biomarker for Breast Cancer Resistance Protein (BCRP/ABCG2) activity. (2024)

Pharmacokinetic research participants.

This is drug-research methodology: it looks at whether riboflavin levels can stand in for the activity of a transporter protein when studying drug interactions. It says nothing about any health benefit of taking riboflavin, and it is not one of the four studies cited on this page.

5
Multivitamin Effects on Plasma Nutrients (China) — Clinical Trial

Randomized, double-blind, controlled trial in China examining multivitamin/mineral supplements on plasma B-vitamin levels. Outcomes: riboflavin, B12, folate, etc.

Chinese adults.

Taking a multivitamin raised blood levels of B vitamins. That only shows the pills are absorbed; it does not show any effect on health, riboflavin was not tested on its own, and this study is not among the four cited on this page.

6
Riboflavin for MTHFR 677TT Genotype — Clinical Trial

Clinical trials examining riboflavin (1.6 mg/day for 12 weeks) effects on homocysteine and BP in patients with MTHFR C677T variant.

MTHFR 677TT genotype patients.

In people carrying two copies of the MTHFR 677T variant, riboflavin was reported to lower homocysteine and blood pressure. Two cautions: these are laboratory and blood pressure readings rather than heart attacks or strokes, and this research is not among the four studies cited on this page, so the trial details cannot be checked here.

7
Riboflavin for Pediatric Migraine — Multiple Studies Review

Review of 7 studies (4 clinical trials) evaluating riboflavin's role in pediatric migraine prevention. (2021)

Pediatric migraine literature.

This 2021 review is not among the four studies cited on this page, so 'modestly effective' is not backed by anything a reader can check here. What the page does cite points the other way: the one pediatric trial cited (42 children, 50 mg per day) found no reduction in migraine attacks, and the cited 2017 systematic review describes the pediatric results as mixed and inconsistent.

8
Riboflavin in Neurological Diseases — Review

Narrative review summarizing clinical trials and studies on riboflavin's therapeutic use in neurological disorders. (2021)

Pooled neurological literature.

Reviews describe doctors using riboflavin in migraine and in rare inherited conditions such as MELAS and Brown-Vialetto-Van Laere syndrome, where a genetic defect blocks riboflavin transport. These are diagnosed diseases managed with medical doses under specialist supervision, not consumer supplement uses, and this review is not among the four studies cited on this page.

Side effects and drug interactions

Common Potential side effects

Urine Discoloration: The most common side effect is bright yellow or orange urine due to the excretion of excess riboflavin, which is harmless.
Gastrointestinal Issues: High doses (e.g., >100 mg/day) may cause mild symptoms like nausea, diarrhea, or stomach discomfort in some individuals.
Allergic Reactions: Rare cases of hypersensitivity or allergic reactions, such as itching, rash, or swelling, have been reported with large doses.
Photosensitivity: In very rare cases, excessive riboflavin intake may increase sensitivity to sunlight, potentially leading to skin reactions.

Important Drug interactions

Potential Drug Interactions: High doses might interfere with certain medications (e.g., tetracycline antibiotics) or affect the efficacy of other B vitamins by altering their metabolism.

Frequently asked questions about Riboflavin

How much riboflavin (B2) should I take?

The RDA is about 1.1 to 1.3 mg per day. Supplements often contain far more, commonly 25 to 100 mg, and the dose used in migraine research is 400 mg per day. That 400 mg dose is a medical dose studied for a diagnosed condition, about 300 times the daily requirement, and is worth discussing with a doctor before starting. Riboflavin is water-soluble and what the body does not use is excreted, so ordinary supplement amounts are well tolerated.

Why does riboflavin turn urine bright yellow?

Riboflavin (vitamin B2) is naturally bright yellow, and the body excretes what it does not use, which harmlessly turns urine vivid yellow. It is a normal, expected effect, not a sign of a problem.

What is riboflavin used for?

Riboflavin is essential for turning food into energy and helps recycle the antioxidant glutathione. Most people get enough from dairy, eggs, meat and fortified grains. At a much higher dose of 400 mg per day it has been studied as a migraine preventive in adults, where one 55-person trial and a later review of 11 trials found a benefit; a trial in 42 children using 50 mg per day found none.

Is riboflavin safe?

At the amounts found in food and everyday supplements, riboflavin has a strong safety record because it is water-soluble and not stored in large amounts. The main visible effect is bright yellow urine, which is harmless. The 400 mg per day migraine dose was studied for about 3 months in the trial cited here, so long-term safety at that level is less well established, and the page's own side-effect list notes that doses above 100 mg per day can cause mild nausea or stomach upset in some people.

What is Riboflavin?

Riboflavin (vitamin B2) is an essential water-soluble vitamin central to energy production and to recycling antioxidants such as glutathione. It also helps activate other B vitamins, including B6 and folate.

What are the signs of Riboflavin deficiency?

Riboflavin (vitamin B2) deficiency, also called ariboflavinosis, is extremely rare in the US but can occur in people with very limited diets, alcohol use disorder, or specific genetic disorders. Riboflavin deficiency rarely occurs alone — it usually appears alongside deficiencies of other B vitamins.

What is the recommended dosage of Riboflavin?

The clinically studied dose is 1.1 to 1.3 mg/day (RDA). Migraine research dose: 400 mg/day in adults, roughly 300 times the daily requirement, studied for a diagnosed condition and appropriate only under a doctor's supervision. A trial in children at 50 mg/day found no benefit. Always follow the product label and check with a healthcare provider for personal advice.

Is Riboflavin safe, and does it have side effects?

For most healthy adults, Riboflavin is well tolerated at studied doses. Reported effects can include: Urine Discoloration: The most common side effect is bright yellow or orange urine due to the excretion of excess riboflavin, which is harmless. Gastrointestinal Issues: High doses (e.g. It may also interact with some medications. Riboflavin is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Riboflavin interact with any medications?

Possible interactions include: Potential Drug Interactions: High doses might interfere with certain medications (e.g., tetracycline antibiotics) or affect the efficacy of other B vitamins by altering their metabolism. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Riboflavin?

NutraSmarts rates the evidence for Riboflavin as Strong (4 out of 5). It is backed by 8 clinical trials and 4 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(4 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Schoenen J, Jacquy J, Lenaerts M. Effectiveness of high-dose riboflavin in migraine prophylaxis. A randomized controlled trial. Neurology. 1998;50(2):466-70. doi: 10.1212/wnl.50.2.466.PubMedUsed to support: Landmark RCT: riboflavin 400 mg/d for 3 months reduced migraine attack frequency and headache days versus placebo (responder rate 59% vs 15%). Primary support for high-dose riboflavin in adult migraine prophylaxis.
  2. Bruijn J, Duivenvoorden H, Passchier J, Locher H, Dijkstra N, Arts WF. Medium-dose riboflavin as a prophylactic agent in children with migraine: a preliminary placebo-controlled, randomised, double-blind, cross-over trial. Cephalalgia. 2010;30(12):1426-34. doi: 10.1177/0333102410365106.PubMedUsed to support: Pediatric crossover RCT in 42 children aged 6 to 13 taking 50 mg per day for 16 weeks in each arm. The primary outcome failed: no significant reduction in migraine attacks versus placebo (P=0.44), and the authors state there is no evidence that 50 mg of riboflavin has a preventive effect on migraine attacks. Only a secondary tension-type and interval headache measure reached significance (P=0.04). Important honesty counterpoint: the adult benefit has not replicated consistently in children.
  3. Thompson DF, Saluja HS. Prophylaxis of migraine headaches with riboflavin: A systematic review. J Clin Pharm Ther. 2017;42(4):394-403. doi: 10.1111/jcpt.12548.PubMedUsed to support: Systematic review of 11 trials: riboflavin showed a consistent prophylactic benefit in adults (5 trials) but mixed/inconsistent results overall, especially in pediatric trials. Supports adult migraine prevention while honestly noting heterogeneity; riboflavin is well tolerated and inexpensive.
  4. Powers HJ. Riboflavin (vitamin B-2) and health. Am J Clin Nutr. 2003;77(6):1352-60. doi: 10.1093/ajcn/77.6.1352.PubMedUsed to support: Authoritative review of riboflavin's role as a precursor of the flavocoenzymes FMN and FAD in energy metabolism, and the clinical features of deficiency (ariboflavinosis). Supports the essential cofactor/deficiency-correction role, including interactions with iron handling and other B vitamins.