Vitamin C levels: what's normal, high and low
A water-soluble antioxidant essential for collagen synthesis and immune function.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
Vitamin C is measured with a standard blood draw after an 8–12 hour fast. A typical reference range is 0.400 – 2.00 mg/dL. At TestWell it's $44.99 all-in as Vitamin C (Ascorbic Acid), results in 3–7 business days, drawn at Quest or Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- mg/dL
- Sample
- Blood draw
- Fasting
- 8–12 hours
- Results
- 3–7 business days
- Price
- $44.99
- Labs
- Quest or Labcorp · BioReference in NY/NJ
Vitamin C Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18+ | 0.400 – 2.00 mg/dL |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
Have a result in hand? analyze it with your AI assistant using these reviewed ranges, or run it through our explainer. Tools: look up another marker's range · convert lab units
What your Vitamin C result may mean
Can reflect inadequate dietary intake. Severe deficiency causes scurvy.
What a low Vitamin C means: causes, symptoms, next steps ↓Educational only — not a diagnosis. Many factors can influence a single result. Discuss anything that concerns you with a healthcare provider.
What does a low Vitamin C mean?
Low vitamin C reflects weeks of low fruit-and-vegetable intake — common with restrictive diets, alcohol use disorder, food insecurity, eating disorders and in smokers, who need about a third more. Absorption problems, dialysis and some cancers also lower it. Severe deficiency is scurvy: bleeding gums, bruising, poor wound healing and fatigue, which reverses within days of repletion. Vitamin C is fragile in the tube, so a low result needs a properly handled sample.
Common causes of a low Vitamin C
- Diet low in fruit and vegetables for several weeks; restrictive or 'carnivore' diets
- Smoking (higher requirement), alcohol use disorder
- Malabsorption, inflammatory bowel disease, bariatric surgery
- Dialysis, critical illness, some cancers
- Sample not protected from light or processed late (false low)
Ordered from most to least common.
Symptoms that can go with it
- Fatigue, irritability
- Bleeding or swollen gums, easy bruising, tiny red spots around hair follicles, corkscrew hairs
- Slow wound healing, joint pain, anemia
What clinicians usually check next
- Repeat with a protected, promptly processed sample
- CBC and iron studies (vitamin C deficiency impairs iron absorption)
- Dietary correction or a modest supplement; symptoms improve within days to weeks
Follow-up tests at TestWell: CBC with Differential ($21.99).
How quickly does scurvy reverse?
Fast — fatigue and gum bleeding improve within days of adequate vitamin C, and most signs resolve within a few weeks.
Can vitamin C be too high?
Serum levels plateau because the kidneys excrete the excess; very high supplement doses mainly risk kidney stones in susceptible people and can interfere with some glucose and stool tests.
Educational only — not a diagnosis. A single result outside the range is a prompt to look closer with a clinician.
How do you get a Vitamin C test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. Vitamin C is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| Vitamin C (Ascorbic Acid) | This marker only | $44.99 |
Quest vs. Labcorp for Vitamin C: which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | Yes | $44.99 |
| Labcorp | Yes | $44.99 |
| BioReference (NY & NJ) | Yes | $21.99 |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
Related Vitamins & Nutrients biomarkers
Markers commonly tested alongside Vitamin C.
Frequently asked
What does a low Vitamin C mean?
Low vitamin C reflects weeks of low fruit-and-vegetable intake — common with restrictive diets, alcohol use disorder, food insecurity, eating disorders and in smokers, who need about a third more. Absorption problems, dialysis and some cancers also lower it. Severe deficiency is scurvy: bleeding gums, bruising, poor wound healing and fatigue, which reverses within days of repletion. Vitamin C is fragile in the tube, so a low result needs a properly handled sample.
How quickly does scurvy reverse?
Fast — fatigue and gum bleeding improve within days of adequate vitamin C, and most signs resolve within a few weeks.
Can vitamin C be too high?
Serum levels plateau because the kidneys excrete the excess; very high supplement doses mainly risk kidney stones in susceptible people and can interfere with some glucose and stool tests.
Do I need a doctor's order to test my vitamin c?
No. TestWell's licensed physician network reviews and approves your order — usually within minutes. You can place an order online without an in-person visit or a referral from your own doctor.
How long does it take to get Vitamin C results?
Most Vitamin C results are available in 1–3 business days after your specimen arrives at the lab. You'll get an email the moment your results are ready, with everything viewable in your TestWell portal.
How much does a Vitamin C test cost?
Our Vitamin C (Ascorbic Acid) starts at $44.99. That's the all-in price — no copays, no insurance hoops, no surprise bills. HSA and FSA cards are accepted.
Do I need to fast before my Vitamin C test?
Yes — for the most accurate result, fast for 8–12 hours before your blood draw. Water is fine; coffee, food, and supplements are not. Your prep instructions will be included with your order.
Which lab will process my Vitamin C test?
Your test will be processed by Quest Diagnostics, Labcorp, or BioReference depending on which is closest to you and which lab carries the test. All three are CLIA-certified and trusted by hospitals nationwide. You'll choose your lab during checkout from 4,000+ locations.
What can throw off a Vitamin C result?
Smoking and nicotine can change a Vitamin C result without anything being wrong. Smoking and nicotine can lower Vitamin C — deficiency is common in smokers and worth correcting. Each is explained on our physician-reviewed "Before your test" pages; when one applies, remove it and retest.
Ready to test your vitamin c?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $44.99.