Vitamin C (Ascorbic Acid)
- What other names is Vitamin C known by?
- What is Vitamin C?
- How does Vitamin C work?
- Are there safety concerns?
- Are there any interactions with medications?
- Dosing considerations for Vitamin C.
Vitamin C (Ascorbic Acid) Safety and Side Effects
Vitamin C is safe for most people when taken by mouth or applied to the skin. In some people, vitamin C might cause nausea, vomiting, heartburn, stomach cramps, headache, and other side effects. The chance of getting these side effects increases the more vitamin C you take. Doses higher than 2000 mg per day might not be safe and may cause a lot of side effects, including kidney stones and severe diarrhea. In people who have had a kidney stone, doses greater than 1000 mg per day greatly increase the risk of kidney stone recurrence.
Vitamin C is likely safe for pregnant or breast-feeding women when taken in the recommended amount of 120 mg per day. Taking too much vitamin C during pregnancy can cause problems for the newborn baby.
Do not take vitamin C in doses greater than those found in basic multivitamins if:
- You have had a heart attack.
- You have had angioplasty, a heart procedure.
- You have cancer.
- You have diabetes...
Most experts recommend getting vitamin C from a diet high in fruits and vegetables rather than taking supplements. Fresh-squeezed orange juice or fresh-frozen concentrate is a better pick than ready-to-drink orange juice. The fresh juice contains more active vitamin C. Drink fresh-frozen orange juice within one week after reconstituting it for the most benefit. It you prefer ready-to-drink orange juice, buy it 3 to 4 weeks before the expiration date, and drink it within one week of opening.
Historically, vitamin C was used for preventing and treating scurvy. These days, vitamin C is used most often for preventing and treating the common cold. Some people use it for other infections including gum disease, acne and other skin conditions, bronchitis, human immunodeficiency virus (HIV) disease, stomach ulcers caused by bacteria called Helicobacter pylori, tuberculosis, dysentery (an infection of the lower intestine), and skin infections that produce boils (furunculosis). It is also used for infections or inflammation of the bladder and prostate, nerve pain, pregnancy-related complications.
Some people use vitamin C for depression, thinking problems, dementia, Alzheimer's disease, physical and mental stress, fatigue including chronic fatigue syndrome (CFS), autism, attention deficit-hyperactivity disorder (ADHD), schizophrenia, Lou Gehrig's disease, and Parkinson's disease. It is also used to treat or prevent toxicity caused by certain drugs or metals and to treat peptic ulcers, swine flu, sudden hearing loss, gout, and tetanus.
Other uses include increasing the absorption of iron from foods. Vitamin C is also used in combination with a drug called deferoxamine to increase removal of iron from the blood. Some people use iron to correct a protein imbalance in certain newborns (tyrosinemia). It is also used to prevent the transfer of HIV from mothers to babies during breastfeeding. Vitamin C is also used to help reduce the side effects of bowel preparation.
There is some thought that vitamin C might help the heart and blood vessels. It is used for heart disease, hardening of the arteries, preventing clots in veins and arteries, heart attack, stroke, high blood pressure, high cholesterol, irregular heartbeat after surgery, nitrite tolerance, or inadequate blood flow that causes blood to pool in the legs. It is also thought that vitamin C may increase the healing of burns, ulcers, fractures, and other wounds. Vitamin C is also used to prevent long-term pain after surgery or injury.
Vitamin C is also used for glaucoma, preventing cataracts, preventing gallbladder disease, dental cavities and plaque, constipation, Lyme disease, age-related vision loss, boosting the immune system, heat stroke, hay fever and other allergy-related conditions, asthma and exercise-induced asthma, bronchitis, cystic fibrosis, sickle cell disease, infertility, diabetes, collagen disorders, arthritis and other types of joint inflammation, back pain and disc swelling, cancer, and osteoporosis and other bone conditions.
Additional uses include improving physical endurance and slowing aging, as well as counteracting the side effects of cortisone and related drugs, aiding drug withdrawal in addiction, and reducing side effects of radiation therapy.
Sometimes, people put vitamin C on their skin to protect it against the sun, pollutants, and other environmental hazards. Vitamin C is also applied to the skin to help with damage from radiation therapy.
Vitamin C is inhaled through the nose to treat hayfever.
- Vitamin C deficiency. Taking vitamin C by mouth or injecting as a shot prevents and treats vitamin C deficiency, including scurvy. Also, taking vitamin C can reverse problems associated with scurvy.
Likely Effective for...
- Iron absorption. Giving vitamin C along with iron can increase how much iron the body absorbs in adults and children.
- A genetic disorder in newborns called tyrosinemia. Taking vitamin C by mouth or as a shot improves a genetic disorder in newborns in which blood levels of the amino acid tyrosine are too high.
Possibly Effective for...
- Age-related vision loss (age-related macular degeneration; AMD). Taking vitamin C, vitamin E, beta-carotene, and zinc helps prevent AMD from becoming worse in people at high risk for developing advanced AMD. It's too soon to know if the combination helps people at lower risk for developing advanced AMD. Also, it's too soon to known if vitamin C helps prevents AMD.
- Decreasing protein in the urine (albuminuria). Taking vitamin C plus vitamin E can reduce protein in the urine in people with diabetes.
- Irregular heartbeat (atrial fibrillation). Taking vitamin C before and for a few days after heart surgery helps prevent irregular heartbeat after heart surgery.
- For emptying the colon before a colonoscopy. Before a person undergoes a colonoscopy, the person must make sure that their colon is empty. This emptying is called bowel preparation. Some bowel preparation involves drinking 4 liters of medicated fluid. If vitamin C is included in the medicated fluid, the person only needs to drink 2 liters. This makes people more likely to follow through with the emptying procedure. Also fewer side effects occur. A specific medicated fluid containing vitamin C (MoviPrep, Salix Parmaceuticals, Inc.) has been approved by the U.S. Food and Drug Administration (FDA) for bowel preparation.
- Common cold. There is some controversy about the effectiveness of vitamin C for treating the common cold. However, most research shows that taking 1-3 grams of vitamin C might shorten the course of the cold by 1 to 1.5 days. Taking vitamin C does not appear to prevent colds.
- Redness (erythema) after cosmetic skin procedures. Using a skin cream containing vitamin C might decrease skin redness following laser resurfacing for scar and wrinkle removal.
- Upper airway infections caused by heavy exercise. Using vitamin C before heavy physical exercise, such as a marathon, might prevent upper airway infections that can occur after heavy exercise.
- Gout. Higher intake of vitamin C from the diet is linked to a lower risk of gout in men. But vitamin C doesn't help treat gout.
- Worsening of stomach inflammation caused by medicine used to treat H. pylori infection. Some medicine used to treat H. pylori infection can worsen stomach inflammation. Taking vitamin C along with one of these medicines called omeprazole might decrease this side effect.
- Abnormal breakdown of red blood cells (hemolytic anemia). Taking vitamin C supplements might help manage anemia in people undergoing dialysis.
- High blood pressure. Taking vitamin C along with medicine to lower blood pressure helps 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). Taking vitamin C does not seem to lower blood pressure when taken without medicine to lower blood pressure.
- Lead poisoning. Consuming vitamin C in the diet seems to lower blood levels of lead.
- Helping medicines used for chest pain work longer. In some people who take medicines for chest pain, the body develops tolerance and the medicines stop working as well. Taking vitamin C seems to help these medicines, such as nitroglycerine, work for longer.
- Osteoarthritis. Taking vitamin C from dietary sources or from calcium ascorbate supplements seems to prevent cartilage loss and worsening of symptoms in people with osteoarthritis.
- Physical performance. Eating more vitamin C as part of the diet might improve physical performance and muscle strength in older people. Also, taking vitamin C supplements might improve oxygen intake during exercise in teenage boys.
- Sunburn. Taking vitamin C by mouth or applying it to the skin along with vitamin E might prevent sunburn. But taking vitamin C alone does not prevent sunburn.
- Wrinkled skin. Skin creams containing vitamin C seem to improve the appearance of wrinkled skin.
Possibly Ineffective for...
- Bronchitis. Taking vitamin C by mouth does not seem to have any effect on bronchitis.
- Asthma. Some people with asthma have low vitamin C levels in their blood. But taking vitamin C does not seem to reduce the chance of getting asthma or improve asthma symptoms in people who already have asthma.
- Hardening of the arteries (atherosclerosis). Higher intake of vitamin C as part of the diet is not linked with a reduced risk of atherosclerosis. Also, taking vitamin C supplements does not seem to prevent atherosclerosis from becoming worse in most people with this condition.
- Bladder cancer. Taking vitamin C supplements does not seem to prevent bladder cancer or reduce bladder cancer-related deaths in men.
- Inherited disorders that damage nerves in the arms and legs (Charcot-Marie-Tooth disease; CMT). Taking vitamin C does not seem to prevent nerve damage from becoming worse in people with Charcot-Marie-Tooth disease.
- Colon cancer. Higher intake of vitamin C from food or supplements is not linked with a lower risk of cancer in the colon or rectum.
- Fracture. Taking vitamin C does not seem to improve function, symptoms, or healing rates in people with a wrist fracture.
- Helicobacter pylori (H. pylori) infection. Taking vitamin C along with medicines used to treat H. pylori infection doesn't seem to get rid of H. pylori better than taking the medicines alone.
- Eye damage associated with a medicine called interferon. Taking vitamin C by mouth does not seem to prevent eye damage in people receiving interferon therapy for liver disease.
- Leukemia. Taking vitamin C does not seem to prevent leukemia or death due to leukemia in men.
- Lung cancer. Taking vitamin C, alone or with vitamin E, does not seem to prevent lung cancer or death due to lung cancer.
- Melanoma. Taking vitamin C, alone or with vitamin E, does not prevent melanoma or death due to melanoma.
- Death from any cause. High blood levels of vitamin C have been linked with a reduced risk of death from any cause. But taking vitamin C supplements along with other antioxidants does not seem to prevent death.
- Pancreatic cancer. Taking vitamin C together with beta-carotene plus vitamin E does not prevent pancreatic cancer.
- High blood pressure during pregnancy (pre-eclampsia). Most research shows that taking vitamin C with vitamin E does not prevent high blood pressure during pregnancy.
- Complications during pregnancy. Taking vitamin C, alone or with vitamin E, does not prevent many pregnancy complications, including preterm birth, miscarriage, stillbirth, and others.
- Prostate cancer. Taking vitamin C supplements does not seem to prevent prostate cancer.
- Skin problems related to radiation cancer treatments. Applying a vitamin C solution to the skin does not prevent skin problems caused by radiation treatments.
Insufficient Evidence to Rate Effectiveness for...
- Hay fever (Allergic rhinitis). Using nasal spray containing vitamin C seems to improve nasal symptoms in people with allergies that last all year. Taking vitamin C by mouth might block histamine in people with seasonal allergies. But results are conflicting.
- Alzheimer's disease. Higher intake of vitamin C from food is linked with a reduced risk of Alzheimer's disease.
- Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Higher intake of vitamin C from food or supplements is not linked with a reduced risk of ALS.
- Stomach damage caused by aspirin. Taking vitamin C might prevent stomach damage caused by aspirin.
- Atopic disease. Higher intake of vitamin C is not linked with a lower risk of eczema, wheezing, food allergies, or allergic sensitization.
- Attention deficit-hyperactivity disorder (ADHD). Taking high doses of vitamins, including vitamin C, does not seem to reduce ADHD symptoms. But taking lower doses of vitamin C along with flaxseed oil might improve some symptoms, such as restlessness and self-control.
- Autism. Early research shows that taking vitamin C might reduce the severity of autism symptoms in children.
- Breast cancer. It's too soon to know if higher intake of vitamin C from food helps prevent breast cancer from developing. But a higher intake of vitamin C from food seems to be linked with a reduced risk of death in people diagnosed with breast cancer. Also, taking vitamin C supplements after being diagnosed with breast cancer seems to help reduce the risk of dying from breast cancer.
- Burns. Early research suggests that receiving a vitamin C infusion within the first 24 hours of severe burns reduces wound swelling.
- Cancer. Higher intake of vitamin C from food is linked with a lower risk of developing cancer. But taking vitamin C supplements doesn't seem to prevent cancer. In people diagnosed with advanced cancer, taking large doses (10 grams) of vitamin C by mouth doesn't seem to improve survival or prevent cancer from getting worse. But high doses of vitamin C might increase survival when given by IV.
- Hardening of the arteries after heart transplant. Early research shows that taking vitamin C and vitamin E for a year after a heart transplant helps prevent hardening of the arteries.
- Heart disease. Research on the use of vitamin C for heart disease is controversial. More research on the use of vitamin C supplements for preventing heart disease is needed. But increasing intake of vitamin C from food might provide some benefit.
- Cataracts. Early research shows that people who take any supplements containing vitamin C for 10 years have a lower risk of developing cataracts. But taking supplements containing vitamin C for less time doesn't seem to help.
- Cervical cancer. Some early research suggests that taking vitamin C reduces the risk of cervical cancer.
- Side effects of chemotherapy. Early research suggests that higher intake of vitamin C from food is linked with fewer chemotherapy side effects in children being treated for leukemia.
- Damage to the colon due to radiation exposure (chronic radiation proctitis). Early research suggests that taking vitamin C plus vitamin E might improve some symptoms of chronic radiation proctitis.
- Long-term pain after surgery or injury. Some research shows that taking vitamin C supplements might help prevent long-term pain after surgery or injury. But other research shows that vitamin C doesn't help and might actually worsen long-term pain following a wrist fracture.
- Kidney damage occurring within 72 hours of treatment with a contrast agent. Some research shows that taking vitamin C before and after receiving a contrast agent helps reduce the risk of developing kidney damage. But other research shows that it doesn't work.
- Dental plaque. Chewing gum containing vitamin C appears to reduce dental plaque.
- Depression. Early research shows that taking vitamin C along with the antidepressant drug fluoxetine reduces depression symptoms in children better than fluoxetine alone.
- Diabetes. Taking vitamin C supplements might improve blood sugar control in people with diabetes. But results are conflicting. Higher intake of vitamin C from food isn't linked with a lower risk of developing diabetes.
- Damage to heart caused by the drug doxorubicin. Early research shows that taking vitamin C, vitamin E, and N-acetyl cysteine may reduce heart damage caused by the drug doxorubicin.
- Cancer that begins in the uterus (endometrial cancer). Higher intake of vitamin C from food might be linked with a lower risk of endometrial cancer. But conflicting results exist.
- Esophageal cancer. Taking vitamin C along with beta-carotene plus vitamin E does not reduce the risk of developing esophageal cancer. But higher intake of vitamin C from food is linked with a lower risk of esophageal cancer.
- Asthma caused by exercise. Taking vitamin C might prevent asthma caused by exercise.
- Gallbladder disease. Taking vitamin C might help to prevent gallbladder disease in women but not men.
- Stomach cancer. Higher intake of vitamin C from food is not linked with a lower risk of stomach cancer in most research. Also, taking vitamin C along with other antioxidants doesn't seem to prevent stomach cancer. But taking vitamin C supplements might prevent precancerous sores in the stomach from progressing to cancer in people at high risk. This includes people previously treated for H. pylori infection.
- HIV/AIDS. Taking high or low doses of vitamin C along with other antioxidants doesn't reduce the amount of HIV in the blood of people with HIV/AIDS.
- HIV transmission. Taking vitamin C along with vitamin B and vitamin E during pregnancy and breast-feeding seems to reduce the risk of transmitting HIV to the infant.
- High cholesterol. Taking vitamin C does not seem to lower cholesterol in people with normal cholesterol levels. But taking vitamin C might reduce low-density lipoprotein (LDL or "bad") cholesterol in people with high cholesterol.
- High phosphate levels. People with kidney disease who are undergoing dialysis often have high blood phosphate levels. Giving vitamin C by IV seems to reduce phosphate levels in these people.
- Sudden hearing loss. Early research shows that vitamin C may improve hearing in people with sudden hearing loss when used with steroid therapy.
- Infertility. There is early evidence that women with certain fertility problems might benefit from taking vitamin C daily.
- Mental stress. Early research suggests that vitamin C might reduce blood pressure and symptoms during times of mental stress.
- Liver disease (nonalcoholic steatohepatitis; NASH). Taking vitamin C along with vitamin E might reduce liver scarring in people with a type of liver disease called nonalcoholic steatohepatitis. But it doesn't seem to decrease liver swelling.
- Cancer that affects white blood cells (Non-Hodgkin lymphoma). Higher intake of vitamin C from foods or supplements is linked with a lower risk of developing non-Hodgkin lymphoma in postmenopausal women.
- Osteoporosis. Some research shows that vitamin C might improve bone strength. But higher vitamin C blood levels in postmenopausal women have been linked to lower bone mineral densities. More information is needed on the effects of vitamin C on bone mineral density.
- Mouth cancer. Higher intake of vitamin C from food is linked with a lower risk of mouth cancer.
- Ovarian cancer. Higher intake of vitamin C from food is not linked with a lower risk of ovarian cancer.
- Parkinson's disease. Higher intake of vitamin C from food is not linked with a lower risk of Parkinson's disease.
- Poor circulation that reduces blood flow to the limbs. Higher intake of vitamin C from food is linked with a lower risk of developing poor circulation in women but not men.
- Pain after surgery. Taking vitamin C one hour after anesthesia reduces the need for morphine after surgery. This suggests that it might reduce pain. But vitamin C doesn't seem to improve satisfaction or the need to use the pain-relieving drug paracetamol.
- Pneumonia. Some research suggests that vitamin C might reduce the risk of pneumonia, as well as the duration of pneumonia once it develops. This effect seems greatest in those with low vitamin C levels before treatment. It's not clear if vitamin C is beneficial in people with normal vitamin C levels.
- Breaking of the amniotic sac before labor begins (premature rupture of membranes; PROM). Taking vitamin C plus vitamin E starting during the second or third trimester and continuing until delivery seems to help prevent the amniotic sac from breaking too early.
- Bed sores (pressure ulcers). Some research suggests that taking vitamin C does not improve wound healing in people with pressure ulcers. But other research shows that taking vitamin C reduces the size of pressure ulcers.
- Restless legs syndrome. Taking vitamin C alone or in combination with vitamin E seems to reduce the severity of restless legs syndrome in people undergoing hemodialysis. But it's not known if vitamin C is beneficial in people with restless legs syndrome that is not related to hemodialysis.
- Sickle cell disease. Taking vitamin C with aged garlic extract and vitamin E might benefit people with sickle cell disease.
- Stroke. Higher intake of vitamin C from food seems to be linked with a reduced risk of stroke. But conflicting results exist. Taking vitamin C supplements doesn't seem to be linked with a reduced risk of stroke.
- Bacterial infection in the nervous system (tetanus). Taking vitamin C along with conventional treatment appears to reduce the risk of death in children with tetanus.
- Urinary tract infections (UTI). Research suggests that taking vitamin C does not prevent UTIs in older people.
- Mental decline caused by reduced blood flow to the brain (vascular dementia). Higher intake of vitamin C and vitamin E from supplements does not seem to be linked with a reduced risk of vascular dementia in Japanese-American men.
- Chronic fatigue syndrome (CFS).
- Cystic fibrosis.
- Dental cavities.
- Kidney disease.
- Lyme disease.
- Other conditions.
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).
Next: How does Vitamin C work?
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