Can Thiamine Cause Urine Cloudiness?
No, thiamine supplementation does not cause urine cloudiness. When thiamine intake exceeds the body's needs, the excess is simply excreted in the urine as water-soluble metabolites, but this does not produce cloudy urine 1.
What Happens to Excess Thiamine
Thiamine is a water-soluble vitamin that cannot be stored in large amounts in the body, with total body stores of only 25-30 mg in adults 2.
When tissues are saturated with thiamine, excess is excreted in urine as pyrimidine metabolites, and with further increased intake, unchanged thiamine appears in the urine 1.
There is no established upper limit for thiamine toxicity because excess is safely eliminated through urinary excretion 2, 3.
High doses (100-500 mg) have been administered without toxic effects, though doses exceeding 30 mg three times daily are not utilized efficiently by the body 1.
Safety Profile of Thiamine Supplementation
Thiamine has an excellent safety profile with minimal side effects even at very high doses 2.
Doses exceeding 400 mg may cause mild nausea, anorexia, and mild ataxia, but these are uncommon 2, 3.
High IV doses rarely cause anaphylaxis, making thiamine one of the safest vitamin supplements available 2, 3.
Common Pitfall to Avoid
If you observe cloudy urine in a patient taking thiamine, look for alternative causes such as urinary tract infection, dehydration with concentrated urine, phosphate crystals, or other medications—not the thiamine itself 2. The cloudiness is coincidental, not causative.