Can a multivitamin cause bright yellow or orange urine in a healthy adult, and is this harmless?

Multivitamin-Induced Urine Color Changes

Yes, multivitamins commonly cause bright yellow or orange urine in healthy adults, and this is completely harmless—it results primarily from excess riboflavin (vitamin B2) excretion and does not indicate any medical problem. 1

Mechanism of Color Change

The yellow-orange discoloration occurs because:

• Riboflavin (vitamin B2) is the primary culprit, causing yellow-colored urine when consumed in amounts exceeding physiological needs 1
• Riboflavin consumed orally from diet or multivitamin supplements rarely causes side effects other than yellow-colored urine 1
• Even massive doses (200× the recommended dietary allowance) of vitamin B2 produce elevated urinary concentrations without causing harm 2
• Beta-carotene supplementation can cause hypercarotenemia or yellowing of the skin (not just urine), though this is also benign 1

Evidence of Safety

Multiple studies confirm this is harmless:

• Riboflavin supplementation at 200 times the recommended dietary allowance caused dramatic increases in urinary riboflavin concentration (from 8.6×10⁴ to 5.7×10⁶ nmol/L) but did not affect health status 2
• Urine color changes from riboflavin do not confound hydration assessment when using standardized color charts in euhydrated individuals 2
• The ESPEN guideline notes that riboflavin consumed from diet or most multivitamin supplements rarely causes side effects, with yellow urine being the only common benign effect 1

Clinical Considerations

Important caveats to remember:

• Only riboflavin (vitamin B2) among commonly tested vitamins and food items causes noticeable changes to urine fluorescence spectrum—other B vitamins (B12) and food items do not produce this effect 3
• The color change reflects excess water-soluble vitamin excretion, which is normal since the body eliminates what it cannot use 1
• Riboflavin supplementation should be avoided before fluorescence spectroscopy testing of urine (e.g., for Coproporphyrin III measurement), as it interferes with spectroscopic analysis 3
• In 24-hour urine collections, riboflavin supplementation may affect urine color assessment as a hydration biomarker, though single-sample assessments remain reliable 4

When to Investigate Further

This benign color change should NOT be confused with pathological causes of abnormal urine color:

• If urine color changes occur without vitamin supplementation, a differential diagnosis should be pursued including medications, foods, metabolic abnormalities, and pathological conditions 5, 6
• Gross examination, specific gravity, pH, dipstick, and microscopic examination can distinguish benign from pathological causes 6

Patient Counseling

Reassure patients that:

• Yellow-orange urine from multivitamins is expected and harmless 1
• This indicates the body is excreting excess water-soluble vitamins it doesn't need 1
• The color change does not indicate kidney problems or vitamin toxicity 2
• No intervention is needed unless other symptoms develop 1