Vitamin C dosage guide: how much to take in 2026

Vitamin C works only at the right dose in the right form. This guide covers the effective range, timing, best forms, and interactions to know.

US RDA

75 to 90 mg daily

Effective dose

500 to 1,000 mg daily for immune and skin support

Upper limit

2,000 mg daily (tolerable upper limit)

Timing

Split doses AM and PM for sustained levels

With food

Optional, better tolerated with food if sensitive stomach

Bioavailability

Liposomal > buffered > ascorbic acid > time-release

Best forms to buy

Ascorbic acid

Standard, cheap

Buffered (sodium ascorbate)

Gentler on stomach

Liposomal

Higher blood levels, more expensive

Ester-C

Gentle, some evidence for longer retention

Signs of deficiency

· Bleeding gums
· Slow wound healing
· Frequent illness
· Fatigue
· Bruising easily

Drug interactions

· Iron absorption is enhanced (helpful if anemic)
· May reduce chemotherapy effectiveness (consult oncologist)

Toxicity

Diarrhea and kidney stone risk at very high doses. Bowel tolerance is your dose ceiling.

FAQ

Common questions

How much Vitamin C should I take?

500 to 1,000 mg daily for immune and skin support

When should I take Vitamin C?

Split doses AM and PM for sustained levels

Can I take too much Vitamin C?

Diarrhea and kidney stone risk at very high doses. Bowel tolerance is your dose ceiling.

This article is for informational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before starting new treatments, supplements, or procedures. Links to products may be affiliate links. Smart Milky may earn a commission at no additional cost to you.