Vitamin B2 (Riboflavin) · low result
What does a low Vitamin B2 (Riboflavin) mean?
Short answer
Low riboflavin (vitamin B2) is uncommon in the US and points to a diet low in dairy, eggs, meat and fortified grains — strict vegan or very restricted eating — or to alcohol use, malabsorption, hypothyroidism, or medications that interfere with it (some antidepressants, phenothiazines, long-term barbiturates). It rarely occurs alone; other B vitamins are usually low too.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
What is the normal range for Vitamin B2 (Riboflavin)?
- age 18+: 137 – 370 nmol/L
Can reflect inadequate dietary intake or malabsorption.
Full reference table, citations and testing options: Vitamin B2 (Riboflavin) biomarker page.
What are the common causes of low Vitamin B2 (Riboflavin)?
- Low intake: vegan or restricted diets without fortified foods
- Alcohol use disorder, malabsorption, eating disorders
- Hypothyroidism, adrenal insufficiency
- Medications: tricyclics, phenothiazines, phenobarbital, probenecid
- Phototherapy in newborns
What symptoms go with low Vitamin B2 (Riboflavin)?
- Cracks at the corners of the mouth, sore red tongue, sore throat
- Scaly rash around the nose and mouth, eye irritation and light sensitivity
- Anemia, fatigue
What do clinicians usually check next?
- B1, B6, B12 and folate — deficiencies cluster
- TSH, dietary review
- Riboflavin is inexpensive and safe to replete under clinician guidance; retest in 8–12 weeks
Follow-up tests available at TestWell: TSH (Thyroid Stimulating Hormone) ($26.99), TSH + Free T4 ($27.99), Folate (Vitamin B9) ($32.99).
How do you recheck Vitamin B2 (Riboflavin)?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Vitamin B2 (Riboflavin) | Test | $66.99 | No | 3–5 business days |
Common questions
Can riboflavin help migraines?
High-dose riboflavin (400 mg/day) has evidence for migraine prevention in some trials; it is a separate use from correcting a deficiency and is a conversation for a clinician.
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.