Why does urine turn yellow after taking vitamin B, and what should I do?

Aug 21, 2025 Source: Cainiu Health

Dr. Cao Zhiqiang

Introduction

Under normal circumstances, yellow urine after taking vitamin B may be caused by factors such as vitamin B2 metabolism, insufficient water intake, urethritis, cystitis, or abnormal liver and gallbladder function. It is recommended to seek timely medical attention to identify the underlying cause, and then improve the condition through medication adjustment, lifestyle care, and drug therapy under a doctor's guidance. In daily life, maintain a light diet, avoid alcohol consumption, and refrain from taking medications that may damage the liver and kidneys.

Generally, yellow urine after taking vitamin B supplements may be caused by vitamin B2 metabolism, insufficient water intake, urethritis, cystitis, or abnormal liver and gallbladder function. It is recommended to seek timely medical consultation to identify the underlying cause and improve the condition under a doctor's guidance through medication adjustments, lifestyle modifications, or pharmacological treatment. The detailed explanations are as follows:

1. Vitamin B2 Metabolism: Vitamin B2 itself is yellow, and the unabsorbed portion is excreted through urine after consumption, resulting in bright yellow-colored urine. This is a normal drug reaction and does not require discontinuation of the medication. Continue taking it as directed by your doctor, while increasing daily water intake to 1500-2000 milliliters to help eliminate metabolic byproducts. Urine color will gradually become lighter.

2. Insufficient Water Intake: Inadequate water consumption during medication reduces the water content in urine, increasing the concentration of vitamin B2 metabolites, which deepens the urine color. Adjust your water intake immediately by drinking small amounts frequently, avoid holding urine, and maintain diluted urine to quickly alleviate yellow urine symptoms.

3. Urethritis: Bacterial infection causing inflammation of the urethra can lead to mucosal congestion due to inflammatory irritation, possibly accompanied by yellow urine, frequent urination, urgency, and painful urination. Patients should follow medical advice to take anti-infective medications such as levofloxacin hydrochloride capsules, cefuroxime axetil tablets, or azithromycin capsules.

4. Cystitis: Infection of the bladder by bacteria or mycoplasma can damage the bladder mucosa due to inflammation, possibly causing yellow urine along with lower abdominal pain and cloudy urine. Patients should follow medical advice to take medications such as cefixime dispersible tablets, ciprofloxacin hydrochloride tablets, or nitrofurantoin enteric-coated tablets for treatment.

5. Abnormal Liver and Gallbladder Function: Vitamin B must be metabolized by the liver. If liver or gallbladder function is impaired, abnormal bilirubin metabolism may cause yellow urine, accompanied by yellowing of the skin and fatigue. Under medical guidance, stop taking vitamin B temporarily and follow instructions to take medications such as silymarin capsules, compound glycyrrhizin tablets, or reduced glutathione tablets to protect liver and gallbladder function.

Maintain a light diet in daily life, avoid alcohol consumption and medications harmful to the liver and kidneys. Strictly follow medical instructions regarding dosage when taking vitamin B; do not increase the dose or take it long-term on your own. Monitor changes in urine color and maintain urinary system and liver/gallbladder health through scientific care.

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