Do you pee out excess vitamin C?

At a vitamin C intake of just 100mg a day, about 25% of it is excreted in your urine.

So yes, you do pee out excess vitamin C. But your kidneys decide what counts as excess, and the line moves with how full you already are: in a landmark NIH study, 6 of 7 volunteers passed none at all until their daily dose reached 100mg.

This guide covers where that line sits, where unabsorbed vitamin C goes, whether peeing it out does harm, and what your urine can and can't tell you.

Table of Contents

1. The Short Answer: Yes, Once You're Close to Full
2. How Much Vitamin C Actually Ends Up in Your Urine
3. The Unabsorbed Excess Takes a Different Exit
4. Is Peeing It Out Harmless? The Oxalate Question
5. What Your Pee Can and Can't Tell You
6. How to Pee Out Less of It
7. Does Liposomal Vitamin C Change the Answer?
8. Frequently Asked Questions
9. Conclusion
10. Research References

1. The Short Answer: Yes, Once You're Close to Full

Your kidneys filter vitamin C out of your blood all day long, then reclaim most of it before it reaches your bladder. That reclaiming has a maximum capacity, so once blood levels climb high enough to exceed it, the surplus stays in the filtrate and leaves in your urine. The German Nutrition Society reports that excretion becomes strongly increased once blood plasma reaches 45 to 60 micromoles per litre (µmol/L), the unit blood tests use.

Below that range, the reverse happens and your kidneys hold on tight. The same German review notes that they step up reabsorption during deficiency, and that on a vitamin C-poor diet urinary excretion falls rapidly to undetectable levels. It treats about 50 µmol/L as the point where body stores are close to saturated.

So the honest answer depends on where you start. In US survey data from 2003–2006, 41.8% of adults had blood levels below 50 µmol/L, and more recent CDC figures show people taking vitamin C-containing supplements, including multivitamins, averaging 70.6 µmol/L against 43.5 µmol/L for non-users. Many people who already take a supplement sit near the level where extra spills over, while many who don't are still below it. For the full science of absorption and excretion, see our guide to why most of a vitamin C dose is wasted.

2. How Much Vitamin C Actually Ends Up in Your Urine

The clearest numbers come from that NIH study, in which seven healthy volunteers spent 4 to 6 months in hospital on a diet with under 5mg of vitamin C a day before taking controlled doses from 30mg to 2,500mg. Because researchers controlled every milligram going in, they could measure exactly what came out.

Set the key numbers side by side and the pattern is hard to miss:

• Below 100mg a day, 6 of 7 volunteers passed no vitamin C in their urine.
• At 100mg a day, about a quarter of intake is excreted.
• At single doses of 500mg or more, whatever the volunteers absorbed was excreted.
• Above 1g a day, less than half of a dose is absorbed at all.

The curve bends because your body can only store so much. Total body vitamin C ranges from about 300mg near scurvy to roughly 2g when full, and the German review puts maximum metabolic losses at about 40–50mg a day, around 3% of the body pool. Once that store is topped up, a large extra dose has nowhere to go but out. For a step-by-step look at a typical supplement dose, see what happens if you take a gram of vitamin C every day.

3. The Unabsorbed Excess Takes a Different Exit

Urine is only one exit. At high doses, much of the vitamin C you swallow doesn't make it into your blood: absorption falls to less than 50% above 1g a day, compared with 70–90% at moderate intakes of 30–180mg.

That unabsorbed vitamin C stays in your gut. According to the German Nutrition Society, it is partly broken down by gut bacteria into organic acids and carbon dioxide and excreted in faeces. It also pulls water into the bowel, and the NIH lists diarrhoea, nausea and abdominal cramps as the most common complaints at high intakes, with an adult upper limit of 2,000mg a day. So "you just pee it out" is only half right: some of the excess is absorbed and then excreted by your kidneys, and some is not absorbed at all.

4. Is Peeing It Out Harmless? The Oxalate Question

For most healthy adults, excreting surplus vitamin C is simply how the body keeps levels steady. The catch is what leaves with it. Breakdown products of vitamin C, including oxalic acid, are mainly excreted in the urine, and in the NIH study oxalate and urate excretion rose at 1,000mg a day compared with lower doses. Higher urinary oxalate could contribute to kidney stones, especially in people with kidney disorders.

One analysis of three large US cohorts of nurses and health professionals found a signal in men only:

• Among 40,536 men followed for about 11 years, total intakes of 1,000mg a day or more carried a 43% higher stone risk than intakes under 90mg.
• For supplements alone, men taking 1,000mg a day or more had a 19% higher risk than non-users.
• Among 156,735 women, neither total nor supplemental vitamin C was significantly linked to stones.

The evidence has limits. Studies of intakes from 30mg to 10g a day have produced conflicting results on urinary oxalate, and the NIH notes the strongest evidence of a stone link is in people who already have hyperoxaluria. If you have had kidney stones, have kidney disease, have haemochromatosis (an iron-overload condition that chronic high doses of vitamin C could worsen), or take regular medication, talk to your doctor before taking high doses. The full safety picture is in our guide to vitamin C side effects and the upper limit.

5. What Your Pee Can and Can't Tell You

If your urine turns neon yellow after a multivitamin or B-complex, the usual culprit is riboflavin (vitamin B2), not vitamin C. The NIH describes riboflavin as naturally yellow and fluorescent, and notes the body absorbs little of it from single doses above 27mg, excreting the absorbed surplus in urine.

Your urine is also a poor guide to your vitamin C status. The German Nutrition Society calls urinary vitamin C insensitive and unreliable as a marker, because levels differ very little between people with inadequate and normal intakes. A blood test is the standard instead, and a plasma level of 50 µmol/L or higher counts as adequate.

The vitamin C you excrete can also interfere with routine urine tests. It is a strong reducing agent, and after a single 1,000mg dose all 33 healthy volunteers in one trial had it in their urine; adding vitamin C to urine samples in the same study produced false-negative test-strip results. In a multicentre study, vitamin C turned up in the urine of 18.1% of people tested, and when it did, 42.3% of glucose and 10.6% of haemoglobin dipstick results were false negatives. If you take high-dose vitamin C and have a urine test coming up, mention it to whoever orders the test.

6. How to Pee Out Less of It

If your goal is to keep more of what you take, work with these limits rather than against them. Three habits make the biggest difference:

• Split large doses. A single 200mg dose was fully absorbed in the NIH study, so two or three smaller doses spread through the day keep each one in the efficient range.
• Don't chase doses your blood can't use. The NIH notes that at intakes of at least 200mg a day, plasma levels increase only marginally, so a bigger dose mostly means more in your urine.
• Start with food. Five varied servings of fruits and vegetables can provide more than 200mg a day, and the vitamin C in food is absorbed as well as the kind in supplements.

Your needs can shift the numbers. Smokers have around 40% higher vitamin C turnover and lower blood levels, so the same intake leaves them further from the point where extra spills over, and the NIH advises that people who smoke need 35mg more a day. For a full daily plan, see our vitamin C dosage guide.

7. Does Liposomal Vitamin C Change the Answer?

Partly, and it's worth being precise about which part. Liposomal vitamin C wraps the vitamin in tiny phospholipid spheres, and a 2025 scoping review found 1.3 to 7.2 times higher total blood exposure (AUC) than standard vitamin C in 9 of 10 trials. The same review cautions that those trials used very different formulations and doses, from 0.15g to 10g, which makes them hard to compare.

Liposomal delivery targets the absorption step, not the kidney threshold. Once vitamin C is in your blood, the same reabsorption limit applies whatever form it arrived in, with excretion climbing steeply once blood levels reach 45 to 60 µmol/L, so a saturated body would still be expected to excrete the surplus. Whether liposomal delivery changes how much ends up in your urine is still an open question: the same review names urinary excretion as a gap for future research. The absorption advantage is well supported; a benefit to health outcomes in people who are already topped up has not been shown.

Bio Absorb Nutraceuticals makes its Liposomal Vitamin C in a GMP-certified facility in Canada, in two formats: a liquid with a natural orange flavour that mixes with water or juice, which makes splitting your intake across the day simple, and capsules that need no refrigeration. Both are verified corn-free, non-GMO, gluten-free, nut-free, dairy-free and vegan, and every batch is third-party tested. See current pricing and serving details for the liquid or the full product specification for the capsules; both come with a 100% money-back guarantee. For the wider comparison, read liposomal versus regular vitamin C and our complete guide to liposomal vitamin C.

Frequently Asked Questions

How long does vitamin C stay in your body?

Longer than "you just pee it out" suggests. A full body holds roughly 2g of vitamin C, and signs of deficiency can appear within about a month of near-zero intake. What your kidneys release is the surplus above their threshold; the store itself runs down over weeks.

Does vitamin C make your pee yellow?

Not noticeably. The neon-yellow urine many people see after a multivitamin comes from riboflavin (vitamin B2), which is naturally yellow; your body absorbs little of it from single doses above 27mg and excretes the absorbed surplus in urine.

Is it bad that I'm peeing out vitamin C?

Not usually. It mostly means your blood levels are already close to full. The main exception is oxalate: in men, total intakes of 1,000mg a day or more were linked to a 43% higher kidney stone risk, so anyone with a history of stones should talk to a doctor before taking high doses.

Is it better to take vitamin C all at once or split it up?

Split it, especially if your daily total runs to several hundred milligrams. In the NIH study, a single 200mg dose was completely absorbed, while at single doses of 500mg and above the absorbed amount was excreted.

Does liposomal vitamin C mean you pee out less?

It can get more into your blood, with 1.3 to 7.2 times the total exposure in 9 of 10 trials, but whether that changes how much you pee out is still an open question: the 2025 review behind those figures lists urinary excretion as something future studies need to measure. Your kidneys' threshold doesn't depend on the form you take, so if you're already topped up, the surplus is still likely to be excreted, and a benefit to health outcomes in people who are topped up hasn't been shown.

Can a urine test show whether I'm getting enough vitamin C?

Not reliably. The German Nutrition Society describes urinary vitamin C as insensitive and unreliable for judging status, and treats a blood level of 50 µmol/L or higher as adequate, so ask your doctor about a blood test instead.

Conclusion

So yes, you pee out excess vitamin C, but "excess" starts where your kidneys say it does, and excretion climbs steeply once blood levels reach 45 to 60 µmol/L. Spread your intake, lead with food, and if getting more of each dose into your blood is the goal, see current pricing and serving details for Bio Absorb's Liposomal Vitamin C.

Research References

1. New Reference Values for Vitamin C Intake. Annals of Nutrition and Metabolism, Vol. 67, No. 1 (2015), pp. 13–20. German Nutrition Society review reporting about 25% urinary excretion at 100mg a day, a sharp rise at plasma levels of 45–60 µmol/L, and faecal loss of unabsorbed vitamin C.
2. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. Proceedings of the National Academy of Sciences of the United States of America, Vol. 93, No. 8 (1996), pp. 3704–3709. NIH depletion–repletion study in 7 volunteers: no urinary vitamin C in 6 of 7 until 100mg a day, and excretion of the absorbed amount at single doses of 500mg and above.
3. Insufficient Vitamin C Levels among Adults in the United States: Results from the NHANES Surveys, 2003–2006. Nutrients, Vol. 13, No. 11 (2021), article 3910. Found 41.8% of US adults with blood vitamin C below 50 µmol/L.
4. Vitamin C Status of US Adults Assessed as Part of the National Health and Nutrition Examination Survey Remained Unchanged between 2003–2006 and 2017–2018. The Journal of Applied Laboratory Medicine, Vol. 8, No. 2 (2023), pp. 272–284. CDC analysis of NHANES 2017–2018: users of vitamin C-containing supplements averaged 70.6 µmol/L serum vitamin C versus 43.5 µmol/L in non-users.
5. Total, Dietary, and Supplemental Vitamin C Intake and Risk of Incident Kidney Stones. American Journal of Kidney Diseases, Vol. 67, No. 3 (2016), pp. 400–407. In 40,536 men, total intakes of 1,000mg a day or more carried a 43% higher stone risk; no significant link in 156,735 women.
6. Influence of vitamin C on urine dipstick test results. Annals of Clinical and Laboratory Science, Vol. 45, No. 4 (2015), pp. 391–395. All 33 volunteers had urinary vitamin C after a single 1,000mg dose; added vitamin C caused false-negative test-strip results.
7. The influence of vitamin C on the urine dipstick tests in the clinical specimens: a multicenter study. Journal of Clinical Laboratory Analysis, Vol. 31, No. 5 (2017), article e22080. Vitamin C appeared in 18.1% of people tested; when present, 42.3% of glucose dipstick results were false negatives.
8. Do Liposomal Vitamin C Formulations Have Improved Bioavailability? A Scoping Review Identifying Future Research Directions. Basic & Clinical Pharmacology & Toxicology, Vol. 137, No. 1 (2025), article e70067. Nine of 10 trials showed higher bioavailability for liposomal vitamin C, with 1.3–7.2-fold higher AUC across very different formulations; identifies urinary excretion as a gap for future research.
9. Vitamin C — Fact Sheet for Health Professionals. National Institutes of Health, Office of Dietary Supplements (2025). Source for absorption by dose, the roughly 2g body store, the 2,000mg adult upper limit, and cautions on kidney stones and haemochromatosis.
10. Riboflavin — Fact Sheet for Health Professionals. National Institutes of Health, Office of Dietary Supplements (2022). Source for riboflavin's yellow colour, limited absorption above 27mg per dose, and urinary excretion of the surplus.

About the Author

David Kimbell is a health writer, digital entrepreneur and former aerospace engineer, based in Ottawa, Canada. He loves translating complex science into clear, actionable guidance for consumers seeking evidence-based solutions.

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Important Disclaimers

Medical Disclaimer: This article provides educational information only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement, especially if you have existing health conditions, take medications, or are pregnant or nursing.

FDA/Health Canada Statement: These statements have not been evaluated by the Food and Drug Administration or Health Canada. This product is not intended to diagnose, treat, cure, or prevent any disease.