Although not fully proven, large doses of vitamin C may help reduce how long a cold lasts. They do not protect against getting a cold. Vitamin C may also be helpful for those exposed to brief periods of severe or extreme physical activity.
The likelihood of success may vary from person to person. Some people improve, while others do not. Taking 1000 to 2000 mg per day can be safely tried by most people. Taking too much can cause stomach upset.
People with kidney disease should NOT take vitamin C supplements.
Large doses of vitamin C supplementation are not recommended during pregnancy.
A balanced diet almost always provides the required vitamin and minerals for the day.
Colds and vitamin C
Fashner J, Ericson K, Werner S. Treatment of the common cold in children and adults. Am Fam Physician. 2012;86(2):153-159. PMID: 22962927 www.ncbi.nlm.nih.gov/pubmed/22962927.
Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013;1. PMID: 23440782 www.ncbi.nlm.nih.gov/pubmed/23440782.
National Institutes of Health, Office of Dietary Supplements. Fact sheet for consumers: vitamin C. Updated February 17, 2016. www.ods.od.nih.gov/factsheets/VitaminC-Consumer/. Accessed April 29, 2016.
Shah D, Sachdev HPS. Vitamin C (ascorbic acid). In: Kliegman RM, Stanton BF, St Geme JW, Schor NF eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 50.
Update Date 1/10/2016
Updated by: Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.