Whenever cold and flu season comes around, many people start thinking about how to look after their health, and vitamin C is often one of the first nutrients that comes to mind. It helps to understand what vitamin C actually does, how much you need, where to get it, and what the evidence really shows. Please note this article is general information only and is not medical advice, so speak with a qualified health professional about your individual needs.
TLDR
- Vitamin C contributes to normal immune function and works as an antioxidant.
- Your body cannot make or store vitamin C, so you need it regularly, and most people can get enough from food.
- The recommended daily intake for most healthy adults in Australia is 45 milligrams.
- Evidence shows regular vitamin C may modestly shorten a cold, but does not prevent colds in most people.
- Starting vitamin C only after symptoms begin has not shown a clear benefit in studies.
- Rest, hydration, good nutrition and everyday habits remain the foundation of staying well.
Vitamin C and your immune system
Vitamin C, also known as ascorbic acid, is an essential nutrient your body needs every day. It plays a role in keeping your skin, blood vessels and bones healthy, and it contributes to normal immune function. Because your body cannot make it or store it, you rely on a steady supply.
What vitamin C does in your body
Vitamin C contributes to normal immune function in several ways. It supports the skin’s role as a barrier, helps various immune cells work effectively, and acts as an antioxidant that helps protect cells from oxidative stress (Nutrients review, 2017, accessed September 2026). These are supportive roles in everyday health, not a shield against illness.
Why demand can rise when unwell
When you are fighting an infection, your body works harder and may use vitamin C more quickly, so levels can fall during illness (Nutrients review, 2017, accessed September 2026). This is one reason people think about their intake in cold and flu season. Meeting your needs consistently through your everyday diet, rather than only when you feel unwell, is the more reliable approach.
How much vitamin C you need
Getting vitamin C from food
For most healthy adults in Australia, the recommended daily intake of vitamin C is 45 milligrams, which is easily met through everyday fruit and vegetables (healthdirect, accessed September 2026). Whole foods also provide fibre and other nutrients that support your health. Good sources include:
- Citrus fruits such as oranges, mandarins and lemons
- Berries, kiwifruit and pineapple
- Capsicum, broccoli and Brussels sprouts
- Tomatoes and leafy green vegetables
- Fresh produce over heavily processed options, as cooking can reduce vitamin C
What the evidence actually shows
It is worth looking honestly at what the research says, because the evidence is more nuanced than the conversation around vitamin C often suggests. A large Cochrane review found that, for most people, regular vitamin C does not prevent colds, though it may modestly reduce how long a cold lasts when taken regularly over time (Cochrane review, 2013, accessed September 2026).
The same review noted that starting vitamin C only after cold symptoms appear has not shown a clear benefit in trials. High-dose intravenous vitamin C has not been shown to prevent or treat colds or flu, and it is not a proven treatment. Vitamin C is not a substitute for rest, good nutrition, vaccination where appropriate, or care from your healthcare provider.
Common belief | What the research suggests |
Vitamin C prevents colds | For most people, regular vitamin C does not prevent colds |
It shortens every cold a lot | Regular intake may modestly reduce cold duration over time |
Taking it once symptoms start fixes a cold | Starting only after symptoms begin has not shown a clear benefit |
IV vitamin C is a proven flu treatment | High-dose IV vitamin C has not been shown to prevent or treat colds or flu |
Reading the evidence this way helps you set realistic expectations and make informed choices with your healthcare provider.
Supporting your body this season
The fundamentals of staying well remain the same every season. These everyday habits are the foundation, and nothing replaces them.
Rest, hydration and good nutrition
Sleep, fluids and a balanced diet are the foundation of a resilient body. Aim for consistent, quality sleep, keep your fluids up through the day, and fill your plate with a variety of colourful fruit and vegetables. These simple habits support your general wellbeing every day.
Everyday habits that help
Small daily choices add up over a season. Regular hand washing, staying active, managing stress and keeping warm all support your general wellbeing. Where appropriate, staying up to date with vaccination is worth discussing with your healthcare provider, particularly before the peak of flu season.
When to see a healthcare provider
Most colds settle with rest and time, but some symptoms need attention. If you have a high fever, difficulty breathing, symptoms that persist or worsen, or you are worried about someone vulnerable, contact your healthcare provider. An IV drip is not a treatment for infection, and medical care always comes first when you are genuinely unwell.
The IV Health Sunshine Coast approach
The team at IV Health Sunshine Coast delivers personalised, practitioner-scripted infusions, vitamin boosters, supplements and wellness testing from its Sippy Downs clinic, with mobile visits available and comprehensive screening behind every session.
Screening comes first
Every plan starts with a nurse consultation that reviews your health history, medications and wellbeing goals, so any next step is based on your individual needs. All treatments carry potential risks and side effects, and your nurse discusses these with you at your consultation so you can make an informed decision.
Where you can access care
Care is available from the Sippy Downs clinic, with mobile visits across the Sunshine Coast and hinterland, and rural visits to Bundaberg, Monto and Crows Nest by expressions of interest. The same clinical process applies wherever your session takes place.
Have questions?
If you would like to talk through your health and whether any next step is right for you, a complimentary discovery call with a nurse via telehealth to determine if this is a good fit for you is available, and there is no obligation to proceed.
This article is intended for general information purposes only and does not constitute medical advice. Please consult a qualified health professional for advice tailored to your individual needs.