# What are the side effects of taking very high doses of Vitamin C?

Canonical page: https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c
Language: en
Category: nutrition
Publisher: ClinicsJo
Published: 2026-09-13T17:52:52.714Z
Content updated: 2026-09-13T17:52:52.714Z
Translation (ar): https://clinicsjo.com/ar/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c

Taking very high doses of vitamin C (ascorbic acid) can lead to noticeable side effects, especially when exceeding 1,000 milligrams per day. Although vitamin C is water-soluble and the body typically excretes excess amounts, large quantities may cause digestive disturbances such as stomach pain, diarrhea, and gas [\[3\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S3>). Furthermore, individuals with hemochromatosis should avoid vitamin C supplements as they may increase iron absorption [\[4\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S4>).

## Common Digestive Symptoms of High Doses

When consuming large amounts of vitamin C supplements, the digestive system is the primary organ that may be affected. The most common side effects associated with doses exceeding 1,000 milligrams per day include:

- Severe stomach pain or intestinal cramps.

- Diarrhea, resulting from the vitamin's direct effect on the intestines when accumulated at high concentrations.

- Bloating and gas (flatulence).

These symptoms are usually considered temporary and fade once the supplements are discontinued or the dosage is reduced to recommended levels [\[3\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S3>).

## Recommended Safe Limit and Special Risks

Adults aged 19 to 64 need only about 40 milligrams of vitamin C daily, an amount easily obtained entirely through a varied and balanced diet containing fruits and vegetables, such as citrus fruits, peppers, and broccoli [\[3\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S3>). Taking vitamin C supplements at doses below 1,000 milligrams per day is unlikely to cause any harm [\[3\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S3>).

However, people with certain medical conditions must exercise extreme caution. For example, if you have hemochromatosis, a disorder that causes excess iron buildup in the body, you should avoid vitamin C supplements. This is because vitamin C can increase the body's iron absorption, which may worsen the condition [\[4\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S4>).

## When Should You Consult a Doctor?

Supplements should not be used as a substitute for a balanced diet except in specific medical cases, such as recovery from burns or surgeries, where a doctor determines the appropriate dosage according to the patient's condition [\[1\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S1>). If you are considering taking vitamin C supplements, especially at high doses, it is essential to consult your doctor or a nutritionist to discuss appropriate dosages and potential risks, particularly if you have any pre-existing medical conditions [\[4\]](<https://clinicsjo.com/en/faq/what-are-the-side-effects-of-very-high-doses-of-vitamin-c#source-S4>).

If persistent symptoms such as severe abdominal pain, continuous diarrhea, or any unusual reactions occur after taking supplements, you should stop using them immediately and consult a healthcare provider. For more details on how to balance your dietary sources, you can view our article on [the benefits of Vitamin C and its natural sources (Arabic)](<https://clinicsjo.com/ar/articles/vitamin-c-benefits-natural-sources-supplements>).

## Medical references

- [Vitamin C](<https://medlineplus.gov/vitaminc.html>)

- [Scurvy](<https://medlineplus.gov/ency/article/000355.htm>)

- [Vitamins and minerals - Vitamin C - NHS](<https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-c/>)

- [Eating, Diet, & Nutrition for Hemochromatosis - NIDDK](<https://www.niddk.nih.gov/health-information/liver-disease/hemochromatosis/eating-diet-nutrition>)

General health education; not a substitute for individualized clinical assessment.

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