Merck Manual

Please confirm that you are a health care professional

honeypot link

Vitamin C Toxicity

(Ascorbic Acid Toxicity)

By

Larry E. Johnson

, MD, PhD, University of Arkansas for Medical Sciences

Last full review/revision Nov 2020| Content last modified Nov 2020
Click here for Patient Education

Intake of > 2 g of vitamin C a day may cause nausea and diarrhea, interfere with the healthy antioxidant-prooxidant balance in the body, and, in patients with thalassemia or hemochromatosis, promote iron overload Overview of Iron Overload Typical adults lose about 1 mg iron (Fe) per day in shed epidermal and gastrointestinal cells; menstruating females lose on average an additional 0.5 to 1 mg/day from menses. This iron loss... read more .

Vitamin C plays a role in collagen, carnitine, hormone, and amino acid formation. It is essential for bone and blood vessel health and wound healing and facilitates recovery from burns. Vitamin C is also an antioxidant, supports immune function, and facilitates the absorption of iron (see table Sources, Functions, and Effects of Vitamins Sources, Functions, and Effects of Vitamins Vitamins may be Fat soluble (vitamins A, D, E, and K) Water soluble (B vitamins and vitamin C) The B vitamins include biotin, folate, niacin, pantothenic acid, riboflavin (B2), thiamin (B1)... read more ).

The upper limit for vitamin C intake is 2000 mg/day.

Up to 10 g/day of vitamin C are sometimes taken for unproven health benefits, such as preventing or shortening the duration of viral infections or slowing or reversing the progression of cancer or atherosclerosis. Such doses may acidify the urine, cause nausea and diarrhea, interfere with the healthy antioxidant-prooxidant balance in the body, and, in patients with thalassemia or hemochromatosis, promote iron overload Overview of Iron Overload Typical adults lose about 1 mg iron (Fe) per day in shed epidermal and gastrointestinal cells; menstruating females lose on average an additional 0.5 to 1 mg/day from menses. This iron loss... read more .

Intake of vitamin C below the upper limit does not have toxic effects in healthy adults.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read
Test your knowledge
Folate Deficiency
Folates are involved in red blood cell maturation and synthesis of purines and pyrimidines. Folate is plentiful in fruits, organ meats (eg, liver), and which of the following food sources?  
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
TOP