The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
Adults (over 18 years old)
The recommended daily intake by the U.S. Food and Nutrition Board of the Institute of Medicine for men more than 18 years old is 90 milligrams daily; for women more than 18 years old, it is 75 milligrams daily; for pregnant women more than 18 years old, it is 85 milligrams daily; and for breastfeeding women more than 18 years old, it is 120 milligrams daily. Recently, some experts have questioned whether the recommended daily intake should be raised. Others have recommended higher intake in some individuals, such as smokers, in whom an additional 35 milligrams daily has been recommended by some.
The upper limit of intake (UL) should not exceed 2,000 milligrams daily in men or women more than 18 years old (including pregnant or breastfeeding women).
Vitamin C administered by mouth or injection is effective for curing scurvy. In adults, 100-250 milligrams by mouth four times daily for one week is generally sufficient to improve symptoms and replenish body vitamin C stores. Some experts have recommended 1-2 grams daily for two days, followed by 500 milligrams daily for one week. Symptoms should begin to improve within 24-48 hours, with resolution within seven days. Treatment should be under strict medical supervision. For asymptomatic vitamin C deficiency, lower daily doses may be used.
For treating the common cold, 1-3 grams daily has been used. For preventing the common cold in people under physical stress, 600-1,000 milligrams of vitamin C daily has been used. During acute stress, one gram of vitamin C three times daily, as a sustained-release preparation, has been used for up to 14 days.
For preventing contrast-mediated nephropathy, three grams of vitamin C is given before coronary angiography and then two grams is given after the procedure, in the evening and again the following morning. For chronic hemodialysis in adults, 100-200 milligrams daily has been used.
For preventing nitrate tolerance, 3-6 grams of vitamin C has been used daily.
For treatment of premalignant gastric lesions, one gram of vitamin C has been used twice daily.
For infertility associated with luteal phase defect, 750 milligrams of vitamin C has been used daily.
For preventing complex regional pain syndrome in patients with wrist fractures, 500 milligrams of vitamin C daily for 50 days has been used.
For preventing gout, 500-1,500 milligrams of vitamin C daily from food and/or supplements has been used.
For high blood pressure, the median vitamin C dose and study duration has been 500 milligrams daily and six weeks, respectively.
Most topical preparations used for aged or wrinkled skin are applied daily and may contain 5-10% vitamin C.
Children (under 18 years old)
The recommended daily intake by the U.S. Food and Nutrition Board of the Institute of Medicine for infants 0-12 months old is human milk content (older recommendations specified 30-35 milligrams); for children 1-3 years old, it is 15 milligrams; for children 4-8 years old, it is 25 milligrams; for children 9-13 years old, it is 45 milligrams; and for adolescents 14-18 years old, it is 75 milligrams for boys and 65 milligrams for girls. The tolerable upper intake levels (UL) for vitamin C are 400 milligrams daily for children 1-3 years old; 650 milligrams daily for children 4-8 years old; 1,200 milligrams daily for children 9-13 years old; and 1,800 milligrams daily for adolescents and pregnant and lactating women 14-18 years old.
For scurvy or vitamin C deficiency in children, 100-300 milligrams of vitamin C daily by mouth in divided doses for two weeks has been used. Older or larger children may require doses closer to adult recommendations. If vitamin C is not available, orange juice may be used for infantile scurvy. Symptoms should begin to improve within 24-48 hours, with resolution within seven days. Treatment should be under strict medical supervision.
For tyrosinemia in premature infants on high-protein diets, 100 milligrams of vitamin C has been used.