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SupplementScience

Vitamin C Side Effects & Safety

This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Generally Safe

Potential Side Effects

  • Gastrointestinal distress (nausea, diarrhea, cramps) at doses above 2,000 mg
  • Increased risk of kidney stones in susceptible individuals at high doses (>1,000 mg/day)
  • May cause false readings in blood glucose monitoring
  • Iron overload risk in individuals with hemochromatosis (vitamin C enhances iron absorption)

Drug & Supplement Interactions

  • Enhances non-heme iron absorption — beneficial for most but risky in hemochromatosis
  • May reduce efficacy of certain chemotherapy drugs (theoretical, debated)
  • High doses may interact with warfarin and affect INR levels
  • Synergistic with vitamin E — vitamin C regenerates oxidized vitamin E

Maximum Dose

Do not exceed: 2,000 mg/day (NIH Upper Tolerable Intake Level); higher doses may cause GI distress

Full Vitamin C Guide

References

  1. (). The roles of vitamin C in skin health. Nutrients. DOI
  2. (). Dietary nutrient intakes and skin-aging appearance among middle-aged American women. American Journal of Clinical Nutrition. DOI
  3. (). Vitamin C: a wound healing perspective. British Journal of Community Nursing. DOI
  4. (). Vitamin C in dermatology. Indian Dermatology Online Journal. DOI