When sick, vitamin C intake of about 1,000 to 2,000 mg (1 to 2 grams) per day is commonly used to potentially help relieve symptoms, though evidence on reducing cold duration and severity is mixed. Some trials found that regular vitamin C supplementation of at least 200 mg/day modestly reduces cold duration, but taking vitamin C after the cold starts does not consistently reduce symptom severity or duration. However, higher therapeutic doses of 6 to 8 grams daily have shown benefits in some studies for reducing cold duration, but such high doses should be approached cautiously due to possible side effects like stomach upset. Generally, taking 1,000 mg daily when symptoms begin is a typical recommendation for symptom alleviation. It is important not to exceed the upper limit of 2,000 mg daily to avoid side effects. Summary:
- Typical dose when sick: 1,000 to 2,000 mg per day
- Regular supplementation at 200 mg/day can modestly reduce cold duration
- Higher doses (6-8g/day) show more efficacy but may cause side effects
- Start supplementation early after symptom onset for best potential effect
- Avoid exceeding 2,000 mg/day to prevent stomach issues
This summary reflects data from recent trials, meta-analyses, and health professional guidelines.
