Side Effects, Interaction and Dosing of Vitamin C

Updated: June 16, 2022

Side Effects, Interaction and Dosing of Vitamin C are discussed below:

Side Effects & Safety of Vitamin C:

Vitamin C is likely safe for most people when taken in recommended doses appropriately. It can be by mouth, applied to the skin, injected into the muscle, and injected intravenously (by IV).
Vitamin C might cause nausea, vomiting, heartburn, stomach cramps, headache, and other side effects in some people. The chance of getting these side effects increases the more vitamin C intake. Amounts higher than 2000 mg daily are unsafe and may cause a lot of side effects, including kidney stones and severe diarrhea. Amounts greater than 1000 mg daily greatly increase the risk of kidney stone recurrence in people who have had a kidney stone.

Special Precautions & Warnings:

Special precautions should be taken for the below cases:

Pregnancy and breast-feeding:

Vitamin C is likely safe for pregnant or breast-feeding women when taken by mouth in recommended dose or when given intravenously (by IV) or intramuscularly and appropriately. The recommended dose is not greater than 2000 mg daily for women over 19 years-old, and 1800 mg daily for women 14 to 18 years-old. Taking too much vitamin C during pregnancy can cause problems for the newborn baby. Vitamin C is unsafe when taken by mouth in excessive amounts.

Infants and children:

Vitamin C is likely safe when taken by mouth appropriately. Vitamin C is unsafe when taken more than the recommended dose orally. The amount should not be higher than 400 mg daily for children 1 to 3 years, 650 mg daily for children 4 to 8 years, 1200 mg daily for children 9 to 13 years, and 1800 mg daily for adolescents 14 to 18 years.

Alcoholism:

Alcohol intake can cause the body to excrete vitamin C in the urine. People who regularly use alcohol, especially those who have other illnesses, often have vitamin C deficiency. These people might need to be treated for a longer time than normal to restore vitamin C levels to normal.

Alzheimer's disease:

Taking vitamin C along with vitamin E and alpha-lipoic acid might worsen mental function in people with Alzheimer's disease.

Angioplasty:

Avoid taking supplements containing vitamin C or other antioxidant vitamins (beta-carotene, vitamin E) immediately before and following angioplasty without the supervision of a health care professional. These vitamins seem to interfere with proper healing.

Weight loss surgery:

Weight loss surgery can cause the body to absorb more oxalate from food. This can increase the amount of oxalate in the urine. Too much oxalate in the urine can cause problems such as kidney stones. Vitamin C can also increase the amount of oxalate in the urine. Taking large amounts vitamin C after weight loss surgery might increase the risk of having too much oxalate in the urine.

Cancer:

Cancerous cells collect high concentrations of vitamin C.  It is advisable to use high doses of vitamin C under the supervision of your oncologist.

Kidney disease:

Vitamin C can increase the amount of oxalate in the urine. Too much oxalate in the urine can increase the risk of kidney failure in people with kidney disease.

Diabetes:

Vitamin C might raise blood sugar. If Vitamin C taken in amounts greater than 300 mg per day may increases the risk of death from heart disease in older women with diabetes. Do not take vitamin C in doses greater than those found in basic multivitamins.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency:

Large amounts of vitamin C can cause red blood cells to break in people with this condition. It is a metabolic deficiency. Avoid excessive amounts of vitamin C.

Kidney stones, or a history of kidney stones:

Large amounts of vitamin C can increase the chance of getting kidney stones. Do not take vitamin C in amounts greater than those found in basic multivitamins.

Heart attack:

Vitamin C levels are reduced during a heart attack. However, low vitamin C has not been linked to an increased risk for heart attack.

Kidney transplant rejection:

Long-term use of vitamin C in high doses before a kidney transplant may increase the risk of transplant rejection or delay how long it takes until the transplanted kidney works.

Schizophrenia:

Taking vitamin C along with vitamin E might worsen psychosis in some people with schizophrenia when taken with antipsychotic drugs.

Smoking and chewing tobacco:

Smoking and chewing tobacco lowers vitamin C levels. Vitamin C intake in the diet should be increased in people who smoke or chew tobacco.

Estrogens interacts with Vitamin C:

The body breaks down estrogens to get rid of them. Vitamin C might decrease the rate of breakdown of estrogens. Taking vitamin C along with estrogens might increase the effects and side effects of estrogens.

Fluphenazine (Prolixin) interacts with Vitamin C:

Large amounts of vitamin C might decrease how much fluphenazine (Prolixin) is in the body. Taking vitamin C along with fluphenazine (Prolixin) might decrease the effectiveness of fluphenazine (Prolixin).

Medications for cancer (Chemotherapy) interacts with Vitamin C:

Vitamin C is an antioxidant. There is some concern that antioxidants might decrease the effectiveness of some medications used for cancers. But it is too soon to know if this interaction occurs.

Medications used for HIV/AIDS (Protease Inhibitors) interacts with Vitamin C:

Taking large doses of vitamin C might reduce how much of some medications used for HIV/AIDS stays in the body. This could decrease the effectiveness of some medications used for HIV/AIDS.<br /> Some of these medications used for HIV/AIDS include amprenavir (Agenerase), nelfinavir (Viracept), ritonavir (Norvir), and saquinavir (Fortovase, Invirase).

Medications used for lowering cholesterol (Statins) interacts with Vitamin C:

Taking vitamin C, beta-carotene, selenium, and vitamin E together might decrease the effectiveness of some medications used for lowering cholesterol. It is not known if vitamin C alone decreases the effectiveness of some medications used for lowering cholesterol. Some medications used for lowering cholesterol include atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), and pravastatin (Pravachol).

Niacin interacts with Vitamin C:

Taking vitamin C along with vitamin E, beta-carotene, and selenium might decrease some of the beneficial effects of niacin. Niacin can increase the good cholesterol. Taking vitamin C along with these other vitamins might decrease the effectiveness of niacin for increasing good cholesterol.

Warfarin (Coumadin) interacts with Vitamin C:

Warfarin (Coumadin) is used to slow blood clotting. Large amounts of vitamin C might decrease the effectiveness of warfarin (Coumadin). Decreasing the effectiveness of warfarin (Coumadin) might increase the risk of clotting. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.
Be watchful with the below combination as there might be minor interaction:

Acetaminophen (Tylenol, others) interacts with Vitamin C:

The body breaks down acetaminophen (Tylenol, others) to get rid of it. Large amounts of vitamin C can decrease how quickly the body breaks down acetaminophen.

Aspirin interacts with Vitamin C:

The body breaks down aspirin to get rid of it. Large amounts of vitamin C might decrease the breakdown of aspirin. Decreasing the breakdown of aspirin might increase the effects and side effects of aspirin. It is advisable not take large amounts of vitamin C if you take large amounts of aspirin.

Choline Magnesium Trisalicylate (Trilisate) interacts with Vitamin C:

Vitamin C might decrease the rate of breakdown of choline magnesium trisalicylate (Trilisate).

Nicardipine (Cardene) interacts with Vitamin C:

Vitamin C is taken up by cells. Taking nicardipine (Cardene) along with vitamin C might decrease the amount of absorption of vitamin C by cells.

Nifedipine interacts with Vitamin C:

Vitamin C is taken up by cells. Taking nifedipine (Adalat, Procardia) along with vitamin C might decrease the amount of absorption of vitamin C by cells.

Salsalate (Disalcid) interacts with Vitamin C:

By Mouth:

General:

The daily recommended dietary allowances (RDAs) are:

• 90 mg for men and 75 mg for women
• Pregnancy and Lactation: 115 mg for age 18 or younger and 120 mg for ages 19 to 50 years
• People who use tobacco should take an additional 35 mg per day.

Do not take more than the following amounts of vitamin C:

• 1800 mg per day for adolescents and pregnant and breast-feeding women 14 to 18 years
• 2000 mg per day for adults and pregnant and lactating women.
• For vitamin C deficiency:
• 100-250 mg once or twice daily for several days for scurvy.

For emptying the colon before a colonoscopy:

2 liters of solution containing polyethylene glycol and vitamin C is used the evening prior to colonoscopy or as a split-dose taken on the evening prior to and the morning of colonoscopy.

For improving iron absorption:

200 mg of vitamin C per 30 mg of iron.

For age-related vision loss (age-related macular degeneration or AMD):

500 mg of vitamin C, 400 IU of vitamin E, and 15 mg of beta-carotene, with or without 80 mg of zinc, per day for up to 10 years.

For treating the common cold:

1-3 grams daily.

For preventing a chronic pain condition called complex regional pain syndrome:

500 mg of vitamin C each day for 50 days starting right after the injury.

For increased protein in the urine (albuminuria):

1250 mg of vitamin C with 680 IU of vitamin E per day for 4 weeks has been used.

For irregular heartbeat or Atrial Fibrillation:

1-2 grams of vitamin C per day for 1-3 days before heart surgery followed by 1-2 grams in two divided doses daily for 4-5 days after heart surgery has been used.

For upper airway infections caused by heavy exercise:

600 mg to 1 gram of vitamin C per day for 3-8 weeks before heavy exercise has been used.

For stomach inflammation or Gastritis:

1200 mg of vitamin C daily along with omeprazole has been used.

For abnormal breakdown of red blood cells or Hemolytic Anemia:

200-300 mg of vitamin C three times per week for 3-6 months has been used.

For high blood pressure:

500 mg of vitamin C per day along with blood pressure-lowering medication has been used.

For helping medicines used for chest pain work longer:

3-6 grams of vitamin C daily has been used.

For osteoarthritis:

1 gram of vitamin C in the form of calcium ascorbate daily for 2 weeks has been used.

For preventing sunburn:

2 grams of vitamin C along with 1000 IU vitamin E taken before sun exposure has been used.

For high cholesterol:

500 mg vitamin C each day for at least 4 weeks.

Applied To The Skin:

For skin redness/rash:

A formulation containing 10% vitamin C, 2% zinc sulfate, and 0.5% tyrosine applied daily for 8 weeks can be used.

For wrinkled skin:

Most topical preparations used for aged or wrinkled skin are applied daily. Creams containing 3% to 10% vitamin C can be used. A specific vitamin C formulation (Cellex-C High Potency Serum) used 3 drops applied daily to areas of facial skin. Avoid applying vitamin C preparations to the eye or eyelids. Also avoid contact with hair or clothes. It can cause discoloration.

By IV:

For irregular heartbeat or Atrial Fibrillation:

2 grams of vitamin C once or twice in the day before heart surgery followed by 1-2 grams daily for 4-5 days after heart surgery has been used.

Children:

By Mouth:

General:

The daily recommended dietary allowances (RDAs) are:

• Infants 0 to 12 months, human milk that itself content 30-35 mg
• 15 mg for Children 1 to 3 years
• 25 mg for Children 4 to 8 years
• 45mg for Children 9 to 13 years
• Adolescents 14 to 18 years, 75 mg for boys and 65 mg for girls
• Pregnancy and Lactation:
• age 18 or younger, 115 mg.

Do not take more than the following amounts of vitamin C:

• 400 mg per day for children ages 1 to 3 years
• 650 mg per day for children 4 to 8 years
• 1200 mg per day for children 9 to 13 years
• 1800 mg per day for adolescents and pregnant and breast-feeding women 14 to 18 years.

For tyrosinemia in premature infants on high protein diets:

100 mg of vitamin C.

For improving iron absorption:

25-70 mg of vitamin C taken with iron-containing foods has been used.

For improving physical performance:

70 mg of vitamin C per day for 2 months can be used in adolescent boys.

By IV:

For tyrosinemia in premature infants on high protein diets:

100 mg of vitamin C can be used.

As A Shot:

For tyrosinemia in premature infants on high protein diets:

100 mg of vitamin C has been used.