Vitamin C (Ascorbic Acid) is generally considered safe. However, high doses can cause side effects. These may include:
heartburn
nausea
Have a headache
Stomach cramps
diarrhea
Kidney stones
Doses of more than 2,000 milligrams are considered extreme. These doses may increase the risk of severe diarrhea and kidney stones.
You can safely take lower doses of vitamin C during pregnancy. A dose of 85 to 120 milligrams per day is the common recommendation. Overuse can cause harm to unborn babies.
Vitamin C can also raise your blood sugar. If you have diabetes, use vitamin C with caution. In older women with diabetes, doses of more than 300 milligrams a day may increase the risk of dying from heart disease.
Drug interaction
If you take estrogen or estrogen-based birth control pills, vitamin C may increase the risk of hormonal side effects. That's because vitamin C may slow down the rate at which estrogen leaves the body.
Vitamin C may also interact with the antipsychotic drug Prolixin to reduce the concentration of the drug in the blood. This may reduce the effectiveness of the drug.
Vitamin C supplements can also reduce the effectiveness of certain chemotherapy drugs.
Let your doctor know if you are taking or plan to take vitamin C and any of these types of medications.
Vitamin C can cause side effects when taken in large doses. These include stomach problems and headaches. Vitamin C may also interact with certain drugs.
Dose and preparation
These recommendations come with two important caveats:
Smokers should take an additional 35 milligrams a day.
If you have been diagnosed with vitamin C deficiency, you need to take 100 to 200 milligrams a day until blood tests show normal vitamin C levels.
Vitamin supplements come in the following forms:
The tablet
capsule
Chewable tablets
fudge
Dissolve powders and tablets
You may also see different types of vitamin C, including:
L-ascorbic acid, usually from corn
A supplement that combines vitamin C with minerals such as sodium or calcium
Citrus organisms flavonoids
Rose hips
No form is more effective than the other. There was no difference in the effectiveness of different types of vitamin C.
