Vitamins & supplements · Water-soluble vitamin
Vitamin C (Ascorbic acid)
Vitamin C is an essential water-soluble vitamin needed for immune function, collagen production, and iron absorption.
OTCKidney warningPaediatric useSenior precautionOverview & typical uses
Vitamin C is an essential water-soluble vitamin needed for immune function, collagen production, and iron absorption.
Primary uses
- Preventing and treating vitamin C deficiency
- Supporting immune and skin health
- Aiding iron absorption from plant sources
How it works
Acts as an essential co-factor for many enzymes, including those in collagen synthesis, and neutralises free radicals as an antioxidant.
Available forms & strengths
- Chewable tablet — 250 mg, 500 mg, 1000 mg (Oral)
- Effervescent tablet — 1000 mg (Oral)
- Oral drops (Oral) · Paediatric
General precautions & contraindications
Do not use if
- Known allergy to ascorbic acid
Pregnancy
Generally considered safe. Recommended within routine daily requirements. Very high supplemental amounts should be discussed with a clinician.
Breastfeeding
Generally considered safe. Safe during breastfeeding.
Kidney considerations
- Very high supplemental amounts may increase kidney-stone risk in susceptible individuals.
Paediatric use
Suitable from infancy with age-appropriate amounts.
Older adults
Well tolerated at normal amounts.
Common side effects
- Mild digestive upset at high amounts
- Occasional diarrhoea with very high daily amounts
Serious warnings — seek help if these appear
- Kidney stones with very high prolonged use in susceptible individuals
- Serious allergic reaction (very rare)
Drug interactions
Very high doses may slightly reduce warfarin effect.
Improves iron absorption — often a helpful combination.
Food & alcohol precautions
No notable food interactions recorded.
Storage, missed dose & overdose
Storage
Store below 25 °C, out of reach of children.
If a dose is missed
Take when remembered — no need to double up.
Overdose
Very high amounts can cause diarrhoea and stomach upset. Kidney-stone risk in susceptible people. Rarely dangerous.
Frequently asked questions
Evidence suggests it may modestly shorten cold symptoms in some people but does not reliably prevent colds.
Medical references
- WHO Model Formulary — Vitamins — World Health Organization
- Institute of Medicine Dietary Reference Intakes — IOM (US)
Content last reviewed: 2025-01-01
Medical disclaimer
This information is for educational purposes only and should not replace professional medical advice. Please consult a licensed pharmacist or clinician for advice tailored to your personal circumstances.