Can you have too much vitamin C?

Understanding how much vitamin C to take can sometimes be confusing. With a wide range of supplements available, many people wonder whether taking high-dose tablets might put them at risk of side effects. 

Vitamin C is essential for immune support, collagen formation and antioxidant protection, but like any nutrient, moderation is important. This guide explains safe intake levels, what counts as “too much” and how to enjoy vitamin C safely through diet and supplementation.

What is the recommended daily dose of vitamin C?

For most adults, the recommended daily intake of vitamin C is approximately 40 mg per day¹. This amount is enough to maintain general health and support key bodily processes such as antioxidant defence.¹

Supplements often provide higher doses, sometimes up to 1,000 mg per tablet.² Although this might appear high, it’s generally considered to be the upper safe limit for daily intake. Regularly exceeding this amount can increase the likelihood of gastrointestinal discomfort, including diarrhoea and stomach cramps, but serious health consequences are uncommon.²

With that in mind, you may worry that taking a 1,000mg supplement as well as your normal diet may mean you consume too much vitamin C. However, foods provide smaller doses of vitamin C, meaning there’s less risk of ingesting too much.  

To illustrate, a medium orange contains around 50 mg of vitamin C,³ a cup of strawberries provides about 85 mg,³ and a red pepper can offer over 100 mg.⁴ Consuming small amounts of these foods in addition to a supplement is unlikely to exceed safe levels. 

But what if you have lots of fruit and veg in your diet? In this case, it’s unlikely that you need vitamin C supplementation at all, as you should get all you need from your food. A different kind of supplement, such as a multivitamin, may be safer for you, as this contains a smaller dose of vitamin C alongside various other vitamins. 

What happens if you take too much vitamin C?

Vitamin C is a water-soluble vitamin, meaning the body does not store it in significant quantities.² Any excess intake is excreted through the urine, which helps prevent toxicity even when higher doses are consumed. This also means that temporary side effects are the main concern rather than long-term harm.

High doses of vitamin C may occasionally cause mild gastrointestinal issues, such as:

• Diarrhoea²
• Nausea²
• Stomach cramps.²

These effects are typically temporary and resolve once intake is reduced. Extremely high intakes over a long period, well beyond the 1,000 mg threshold, could potentially contribute to kidney stones in people who have other risk factors.² However, this is rare and usually only occurs with chronic excessive supplementation rather than dietary intake alone.

Because vitamin C is water-soluble, most of what the body does not use is naturally excreted. This allows for a degree of flexibility, making it usually safe to combine supplements with vitamin C-rich foods such as kiwis, oranges, strawberries and peppers.⁴

Balancing supplements and diet

When taking vitamin C supplements, it is useful to consider your overall diet. A single 1,000 mg tablet provides a substantial amount of vitamin C,² but eating a balanced diet containing multiple fruits and vegetables is unlikely to push total intake past the upper safe limit.

Incorporating foods naturally rich in vitamin C offers additional nutritional benefits beyond the vitamin itself. Fruits and vegetables also provide fibre, antioxidants and other micronutrients that work together to support overall health.³ Therefore, supplementation should be viewed as a complement to a healthy diet rather than a replacement.

Who should be cautious?

Although most adults can safely take up to 1,000 mg of vitamin C per day, certain individuals may need to exercise caution. Those with kidney disorders, a history of kidney stones or specific metabolic conditions may be more sensitive to high doses and should seek professional advice before supplementing.² 

Pregnant or breastfeeding individuals should also check with a healthcare provider to ensure their vitamin C intake meets their specific needs without exceeding safe limits.

Practical tips for safe vitamin C intake

• Moderation is key: Stay within the recommended limits and avoid habitually exceeding 1,000 mg per day.²
• Spread out doses if needed: Dividing a high-dose supplement into smaller amounts throughout the day may reduce the chance of mild gastrointestinal discomfort.²
• Focus on diet: Prioritise vitamin C-rich foods to meet your daily requirements naturally.⁴ Supplements are most useful when dietary intake is insufficient.
• Stay hydrated: Drinking water helps the body excrete excess vitamin C efficiently.²
• Consult a professional: If you have pre-existing conditions or take other medications, professional guidance can ensure supplementation is both safe and effective.²

Vitamin C is an essential nutrient that supports many aspects of health. Combining a diet rich in fruits and vegetables with moderate supplementation is generally safe for healthy adults. Temporary side effects may occur if intake exceeds 1,000 mg per day, but serious toxicity is extremely rare. By staying mindful of intake levels and including natural sources of vitamin C in your meals, you can enjoy the benefits of this important nutrient safely and effectively.

References 

1. Institute of Medicine. (2000). Dietary reference intakes for vitamin C, vitamin E, selenium, and carotenoids. National Academies Press. https://doi.org/10.17226/9810
   
2. National Health Service (NHS). (2023). Vitamin C (ascorbic acid). Retrieved September 21, 2025, from https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-c/
3. U.S. Department of Agriculture. (n.d.). FoodData Central: Oranges, raw. Retrieved September 21, 2025, from https://fdc.nal.usda.gov/
   
4. U.S. Department of Agriculture. (n.d.). FoodData Central: Peppers, sweet, red, raw. Retrieved September 21, 2025, from https://fdc.nal.usda.gov/