For a healthy adult, a dangerous vitamin C overdose is very unlikely, but taking too much can definitely upset your stomach. The adult upper limit is 2,000 mg a day from food and supplements combined.
Go well past it and the usual result is diarrhea, nausea or cramps, which settle once you cut back. A few people, including anyone with a history of kidney stones or the iron-overload condition hemochromatosis, should be more careful with high doses.
The short answer
- Adults need 75 mg (women) or 90 mg (men) of vitamin C a day; people who smoke need 35 mg more.
- The adult upper limit is 2,000 mg a day, counting food and supplements together.
- Too much mostly causes diarrhea, nausea and cramps, and those fade when you take less.
- Above about 1,000 mg a day, absorption drops below half and your body clears the extra.
- Kidney stones, hemochromatosis, cancer treatment or niacin-statin therapy: check with a clinician first.
Can you overdose on vitamin C?
Not in the way most people picture an overdose. The NIH Office of Dietary Supplements (ODS) describes vitamin C as having low toxicity: high intakes are not believed to cause serious adverse effects. What they do cause, past a point, is a gut problem. Vitamin C your intestine doesn't absorb pulls water into the bowel, and the result is diarrhea, nausea or abdominal cramps.
That gut reaction is also what the official safety ceiling is built on. When the Institute of Medicine (IOM) set the vitamin C upper limit in 2000, it chose digestive upset as the deciding effect. Its panel found no clear evidence that high intakes cause kidney stones or excess iron absorption in apparently healthy people.
Translation: you can take more vitamin C than your gut wants, and your gut will tell you. Megadose marketing tends to skip that part.
How much vitamin C do you need per day?
Less than you might think. These are the Recommended Dietary Allowances (RDAs) for adults from ODS:
| Who | Vitamin C per day |
|---|---|
| Women, 19 and older | 75 mg |
| Men, 19 and older | 90 mg |
| Pregnancy (19 and older) | 85 mg |
| Breastfeeding (19 and older) | 120 mg |
| People who smoke | Add 35 mg (110 mg for women, 125 mg for men) |
So if you're a woman asking how much vitamin C per day you need, the answer is 75 mg, rising to 85 mg in pregnancy and 120 mg while breastfeeding.
Food covers that comfortably for most people. ODS notes that five varied servings of fruits and vegetables a day can provide more than 200 mg of vitamin C. Citrus, red and green peppers, kiwifruit, broccoli, strawberries and Brussels sprouts are among the best sources.
Vitamin C does a lot with those milligrams. Your body needs it to make collagen, for example (here's what vitamin C does for skin). If you're also wondering about morning versus evening or with or without food, see the best time to take vitamin C.
How much vitamin C is too much?
For adults, more than 2,000 mg a day is too much. That figure is the Tolerable Upper Intake Level (UL), which ODS defines as the maximum daily intake unlikely to cause adverse health effects. It applies to all your vitamin C, food and supplements together, and it is lower for children.
| Age | Upper limit per day |
|---|---|
| 1–3 years | 400 mg |
| 4–8 years | 650 mg |
| 9–13 years | 1,200 mg |
| 14–18 years (including pregnancy and breastfeeding) | 1,800 mg |
| 19 and older (including pregnancy and breastfeeding) | 2,000 mg |
Where does 2,000 mg come from? The IOM panel relied on a study in which healthy volunteers raised their vitamin C by 1 g a day each week and reported bloating, cramping and diarrhea at 3 to 4 g a day.
The panel set 3 g a day as the lowest level causing problems, divided it by a safety factor of 1.5, and arrived at 2 g. Because the effect is mild and reversible, it saw no need for a bigger margin.
Kids are a different story. A 1,000 mg serving is above the upper limit for children 8 and under, so children's vitamin C doses are a question for their pediatrician.
| Daily amount | What it means |
|---|---|
| 75 mg / 90 mg | Adult RDA for women / men (ODS) |
| About 200 mg | What five servings of fruit and vegetables can supply; above this, blood levels rise only slightly (ODS) |
| 1,000 mg | Daily intake at which blood plasma was fully saturated in an NIH study of seven volunteers (Levine 1996) |
| 2,000 mg | Adult upper limit, food plus supplements (IOM) |
| 3,000 mg | Lowest intake the IOM linked to digestive upset (IOM) |
Now add up a typical day. One 5 mL serving of Infinite Labs Liposomal Vitamin C+ (1,000 mg) plus five servings of fruit and vegetables (about 200 mg) lands around 1,200 mg, a comfortable 800 mg under the adult limit.
Take two servings with the same meals and you're near 2,200 mg, past it. Count the vitamin C in multivitamins, cold-season blends and fortified cereals as well, and if you take zinc and vitamin C together in one product, its vitamin C goes on the tally too.
What happens if you take too much vitamin C?
Is too much vitamin C bad for you? Mostly for your gut. The effects run from common and harmless to uncommon and specific to certain people.
Digestive upset
This is the big one, and the most common complaint. Your intestine absorbs vitamin C through a transport system that saturates, so at high doses more of it stays in the gut. There it draws water into the bowel, which shows up as diarrhea, nausea, abdominal cramps or gas.
The IOM calls these effects generally not serious and self-limiting: reduce your supplemental vitamin C and they go away.
Kidney stones
High intakes can raise the oxalate and uric acid in your urine, which could contribute to kidney stones. In an inpatient NIH study, oxalate and urate excretion were higher at 1,000 mg a day than at lower doses (Levine 1996).
Whether that translates into more stones is less clear: ODS calls the evidence conflicting, with the strongest link in people who already have high urinary oxalate (hyperoxaluria).
A large study of nearly 200,000 adults splits by sex. Ferraro and colleagues (2016) followed 156,735 women and 40,536 men for about 11 years. Men taking 1,000 mg or more a day from supplements had a 19% higher risk of a first kidney stone than men taking none (hazard ratio 1.19, 95% CI 1.01–1.40).
Women showed no significant link, and vitamin C from food wasn't linked to stones in either group. Intake came from questionnaires, so this is an association rather than proof of cause. If you've had a stone or have kidney disease, ask your clinician what total intake makes sense for you.
Iron overload in hemochromatosis
Vitamin C helps you absorb nonheme iron, the form in plant foods such as beans, lentils and spinach (ODS iron guide). For most people that's a plus, and ODS says it does not appear to be a concern in healthy individuals.
The exception is hereditary hemochromatosis, where the body already stores too much iron: there, regularly taking high doses of vitamin C could make iron overload worse.
Why your body sheds extra vitamin C
Your body runs vitamin C on a tight budget, which helps explain why a true overdose is so hard to reach. According to ODS, you absorb about 70% to 90% of vitamin C at moderate intakes of 30 to 180 mg a day.
Above 1 g a day, absorption falls below 50%, and the absorbed vitamin C your body doesn't use leaves in your urine. What isn't absorbed at all leaves in your stool, which is where the digestive symptoms come from.
The classic evidence comes from Levine and colleagues (1996), who kept seven healthy volunteers in hospital for four to six months on a diet with almost no vitamin C, then tested daily doses from 30 to 2,500 mg.
Blood plasma was fully saturated at 1,000 mg a day. A single 200 mg dose was completely absorbed, while at single doses of 500 mg and above, absorption declined and the extra was excreted. The sample was small, but the pattern matches what ODS describes for everyone: the body tightly controls the vitamin C in your blood and tissues.
Urine for the absorbed surplus, stool for the rest: either way, extra vitamin C doesn't keep piling up in your blood. That makes vitamin C one of the more forgiving nutrients to dose, as long as you respect the 2,000 mg ceiling.
Who should check with a clinician first?
For most healthy adults, staying within the upper limit is all the caution needed. These groups should get personal advice before taking high-dose vitamin C, based on ODS guidance:
- Kidney stones or kidney disease. High intakes can raise urinary oxalate, and the stone link is clearest in people with hyperoxaluria.
- Hereditary hemochromatosis. Regular high doses of vitamin C could worsen iron overload, and the ODS iron guide says people with this condition should avoid iron supplements and vitamin C supplements.
- Chemotherapy or radiation. It is uncertain whether antioxidant supplements interact with these treatments, so talk to your oncologist before taking vitamin C, especially at high doses.
- Niacin with simvastatin. Vitamin C taken with other antioxidants may blunt the rise in HDL cholesterol from this combination; ODS advises lipid monitoring for people combining statins and antioxidant supplements.
Quick answers
Is 2,000 mg of vitamin C too much when you are sick?
It's the adult upper limit, not a target. According to ODS, regular intakes of at least 200 mg a day don't appear to reduce how often the general population catches colds, but might modestly shorten colds and ease symptoms.
Starting vitamin C after symptoms begin doesn't appear to help. If you take extra when you're sick, add it to your food total and keep the day at or under 2,000 mg.
What does vitamin C toxicity look like?
Mostly digestive: diarrhea, nausea, stomach cramps and gas. These usually settle when you cut back. If symptoms are severe or don't improve after you lower the dose, see a doctor.
Can you get too much vitamin C from food?
Very unlikely. The upper limit counts food, but five varied servings of fruit and vegetables provide more than 200 mg, still a long way from 2,000 mg. In the Ferraro cohorts of nearly 200,000 adults, few people got more than 700 mg a day from food.
Does liposomal vitamin C change the upper limit?
No. The 2,000 mg limit covers total vitamin C from food and supplements in any form. Liposomal describes how the vitamin C is packaged with phospholipids; it doesn't come with a separate limit, so count it the same way. For more on the format itself, here's what liposomal means.
Where Vitamin C+ fits
If you want a supplement, a measured dose makes the math easy. Vitamin C+ gives you 1,000 mg of vitamin C in one 5 mL (1 teaspoon) serving: half the adult upper limit, with plenty of room left for the vitamin C in your meals.
For anyone who would rather stir a teaspoon into a drink than swallow another capsule, it's a strong pick: one clear number and a daily total that stays comfortably under the ceiling.
The vitamin C comes from sodium ascorbate and ascorbic acid, and sunflower lecithin supplies the phospholipids for the liposomal format. The label lists 124 mg of sodium per serving, so you can count it if you track your sodium.
Take 5 mL a day in water or juice, or as directed by your healthcare professional. Shake before use, refrigerate after opening and use within 45 days. A bottle holds 30 servings, so taken daily it's finished well inside that window. Vitamin C+ is third-party tested and made in GMP-certified facilities, and certificates of analysis are available on request.
The practical takeaway
How much vitamin C should you take? At least the RDA, ideally starting with fruit and vegetables, and no more than 2,000 mg a day once you add up food and supplements. If your gut complains, ease off and it should settle.
If you're in one of the check-first groups above (stone history, kidney disease, hemochromatosis, cancer treatment, niacin with a statin), talk to your clinician before taking high doses. For everyone else, vitamin C is one of the easiest nutrients to get right: pick a sensible daily dose and let your body handle the rest.
Sources
- NIH Office of Dietary Supplements. Vitamin C: Fact Sheet for Health Professionals. Updated July 31, 2025.
- Institute of Medicine. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids, chapter 5: Vitamin C. National Academies Press, 2000.
- Levine M et al. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. PNAS, 1996.
- Ferraro PM et al. Total, dietary, and supplemental vitamin C intake and risk of incident kidney stones. American Journal of Kidney Diseases, 2016.
- NIH Office of Dietary Supplements. Iron: Fact Sheet for Consumers.
Educational information, not medical advice. Infinite Labs Liposomal Vitamin C+ is not intended to diagnose, treat, cure, or prevent any disease.
About the author
Arjun Sareen is CEO of Infinite Labs and Infinite Labs Digital and a contributor to the Infinite Labs Journal. This brand-owned guide provides educational information, not individual medical advice.
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