VITAMIN C (ASCORBIC ACID): Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews (2024)

Vitamin C is an essential vitamin that must be consumed in the diet. Good sources include fresh fruits and vegetables, especially citrus fruits.

Vitamin C is needed for the body to develop and function properly. It plays an important role in immune function. Most experts recommend getting vitamin C from the diet rather than taking supplements. Fresh oranges and fresh-squeezed orange juice are good sources.

Historically, vitamin C was used for preventing and treating scurvy. Today, people most commonly use vitamin C for preventing and treating the common cold. It's also used for autism, breast cancer, heart disease and many other conditions, but there is no good scientific evidence to support many of these uses. There is also no good evidence to support using vitamin C for COVID-19.

• Vitamin C deficiency. Taking vitamin C by mouth or injecting it as a shot prevents and treats vitamin C deficiency, including scurvy. Also, taking vitamin C can reverse problems associated with scurvy. Only a healthcare provider can inject vitamin C as a shot.

• Low levels of red blood cells in people with a long-term illness (anemia of chronic disease). Taking vitamin C supplements by mouth might help manage anemia in people undergoing dialysis.
• Irregular heartbeat (atrial fibrillation). Taking vitamin C by mouth or by IV before and after heart surgery helps prevent irregular heartbeat after heart surgery. IV products can only be given by a healthcare provider.
• Emptying the colon before a colonoscopy. A specific fluid containing vitamin C (MoviPrep, Salix Pharmaceuticals, Inc.) has been approved by the FDA for bowel preparation before a colonoscopy. Some bowel preparations involve drinking 4 liters of medicated fluid. If vitamin C is included in the fluid, only 2 liters are needed.
• Common cold. Taking 1-3 grams of vitamin C by mouth might shorten the course of a cold by 1 to 1.5 days. But taking vitamin C does not appear to prevent colds.
• Limb pain that usually occurs after an injury (complex regional pain syndrome). Taking vitamin C by mouth after surgery or injury seems to prevent complex regional pain syndrome from developing.
• Recovery from laser skin therapy. Applying a skin cream containing vitamin C might decrease skin redness after laser skin therapy for scar and wrinkle removal.
• Airway infections caused by exercise. Taking vitamin C by mouth before heavy physical exercise, such as a marathon or army training, might prevent upper airway infections that can occur after heavy exercise.
• High cholesterol. Taking vitamin C by mouth might reduce low-density lipoprotein (LDL or "bad") cholesterol in people with high cholesterol.
• High blood pressure. Taking vitamin C by mouth might help lower systolic blood pressure (the top number in a blood pressure reading) by a small amount. But it does not seem to lower diastolic pressure (the bottom number).
• Lead poisoning. Consuming vitamin C in the diet seems to lower blood levels of lead.
• Reduced benefit of nitrate therapy that happens when nitrates are used all day (nitrate tolerance). Taking vitamin C by mouth seems to help drugs for chest pain, such as nitroglycerin, to work longer.
• Pain after surgery. Taking vitamin C by mouth or by IV might reduce pain during the first 24 hours after surgery. But it's unclear if taking vitamin C by mouth can reduce pain during the first 6 weeks after surgery. IV products can only be given by a healthcare provider.
• Wrinkled skin. Applying skin creams containing vitamin C seems to improve the appearance of wrinkled skin. Apply a vitamin C patch also seems to help reduce wrinkles.

• Short-term swelling (inflammation) of the airways in the lungs (acute bronchitis). Taking vitamin C by mouth does not seem to have any effect on bronchitis.
• Asthma. Taking vitamin C by mouth doesn't seem to prevent asthma or improve symptoms in people who already have asthma.
• Hardening of the arteries (atherosclerosis). Taking vitamin C by mouth does not seem to prevent atherosclerosis from becoming worse in most people with this condition.
• Bladder cancer. Taking vitamin C by mouth does not seem to prevent bladder cancer or reduce bladder cancer-related deaths.
• Heart disease. Taking vitamin C by mouth does not prevent heart disease or reduce death due to heart disease.
• Colon cancer, rectal cancer. Taking vitamin C by mouth does not seem to prevent cancer in the colon or rectum.
• Coronavirus disease 2019 (COVID-19). Taking high-dose vitamin C by mouth does not seem to speed up recovery from COVID-19 in people who aren't in the hospital. Giving vitamin C by mouth or IV to people who are in the hospital with severe COVID-19 might have some benefit, but more studies are needed to say for sure.
• Death of an unborn or premature baby. Taking vitamin C by mouth, alone or with other supplements, during pregnancy doesn't prevent death of an unborn or premature baby.
• Fractures. Taking vitamin C by mouth does not seem to improve function, symptoms, or healing rates in people with a wrist fracture.
• A digestive tract infection that can lead to ulcers (Helicobacter pylori or H. pylori). Taking vitamin C by mouth along with medicines used to treat H. pylori infection doesn't seem to get rid of H. pylori faster than taking the medicines alone.
• A group of inherited disorders that leads to muscle weakness and numbness in the arms and legs. Taking vitamin C by mouth for one or two years does not seem to prevent nerve damage in people with these disorders.
• Eye damage in people taking drugs called interferons (interferon-related retinopathy). Taking vitamin C by mouth does not seem to prevent eye damage in people receiving interferon therapy for liver disease.
• Cancer of the white blood cells (leukemia). Taking vitamin C by mouth doesn't seem to prevent leukemia or death due to leukemia.
• Lung cancer. Taking vitamin C by mouth, alone or with vitamin E, doesn't seem to prevent lung cancer or death due to lung cancer.
• The most serious type of skin cancer (melanoma). Taking vitamin C by mouth, alone or with vitamin E, doesn't prevent melanoma or death due to melanoma.
• Miscarriage. Taking vitamin C by mouth, alone or with other supplements, during pregnancy does not prevent miscarriage.
• Death from any cause. Taking vitamin C by mouth along with other antioxidants does not seem to prevent death.
• Pancreatic cancer. Taking vitamin C by mouth together with beta-carotene plus vitamin E does not seem to prevent pancreatic cancer.
• A pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia). Taking vitamin C by mouth with vitamin E during pregnancy does not prevent high blood pressure and protein in the urine during pregnancy.
• Preterm birth. Taking vitamin C by mouth, alone or with other supplements, during pregnancy does not prevent preterm birth.
• Prostate cancer. Taking vitamin C by mouth does not seem to prevent prostate cancer.
• Skin damage caused by radiation therapy (radiation dermatitis). Applying a vitamin C solution to the skin does not prevent skin problems caused by radiation treatments.
• Infants with birth weight below the 10^th percentile. Taking vitamin C by mouth, alone or with other supplements, during pregnancy does not reduce the chance of giving birth to an infant with a low birth weight.
• Stillbirth. Taking vitamin C by mouth, alone or with other supplements, during pregnancy does not reduce the chance of having a stillbirth.

There is interest in using vitamin C for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

• Blood infection (sepsis). Giving vitamin C by IV with or without thiamine and/or a steroid does not reduce the risk of dying, organ damage, hospitalization duration, or the need for supportive treatment in people with sepsis.

There is interest in using vitamin C for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

When taken by mouth: Vitamin C is likely safe for most people. In some people, vitamin C might cause side effects such as stomach cramps, nausea, heartburn, and headache. The chance of getting these side effects increases with higher doses. Taking more than 2000 mg daily is possibly unsafe and may cause kidney stones and severe diarrhea. In people who have had a kidney stone, taking amounts greater than 1000 mg daily increases the risk of getting more kidney stones.

When applied to the skin: Vitamin C is likely safe for most people. It might cause irritation and tingling.

Vitamin C is an important nutrient. Fresh fruits and vegetables, especially citrus fruits, are good sources of vitamin C. The amount that should be consumed on a daily basis is called the recommended dietary allowance (RDA). For adult males, the RDA is 90 mg daily. For females 19 years and older, the RDA is 75 mg daily. While pregnant and breastfeeding, the RDA is 120 mg daily for people 19-50 years old. In children, the RDA depends on age.

Vitamin C is also available in supplements, combination products, liquids, lotions, creams, serums, sprays, and patches. Supplements have been used safely by adults in doses up to 2000 mg daily. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.