There are plenty of claims about which remedies keep colds and flu at bay. We put them to the test.
The effectiveness of remedies varies between individuals. Some supplements show more effect in people with existing deficiencies.
A 2011 Cochrane Review of research trials found that when taken within 24 hours of onset of the first symptoms, medications containing zinc can help reduce the duration and severity of the common cold in otherwise healthy people. It is thought zinc interferes with the way cold viruses multiply. More research is needed to understand the ideal dose, formulation and length of treatment. Zinc lozenges can cause stomach upsets and zinc should only be used short term due to concerns about toxicity.
Taking vitamin C to prevent catching a cold doesn’t seem to work unless you are into extreme exercise or you’re going to be in extreme cold. However, taking vitamin C regularly in doses of more than 200mg a day may help reduce the effects of a cold — by around eight per cent in adults and 14 per cent in children. In studies where vitamin C was taken after catching a cold there was no consistent effect on the duration or severity of symptoms.
A 2011 Cochrane Review found that while there was limited data, using probiotics seemed to reduce the incidence of acute upper respiratory tract infection, as well as reducing antibiotic use.
Trials are inconsistent as many different preparations include echinacea. However, some preparations do appear to help decrease the severity and duration of cold symptoms.
Laboratory evidence supports garlic’s antiviral properties but there are few trials on its effect on colds. One study found people who took garlic daily for three months had fewer colds than the group taking a placebo. When they had a cold, however, the length of illness was similar in both groups. And possible side effects included odour and skin rashes.
Top ways to boost immunity
The best way to help strengthen the immune system is to adopt a healthy lifestyle by:
➜ keeping up with vaccinations
➜ avoiding smoking
➜ eating plenty of fruit, vegetables, whole grains and healthy fats, while keeping saturated fat levels low
➜ engaging in regular physical activity
➜ finding ways to de-stress
➜ achieving and maintaining a healthy weight
➜ getting 7-8 hours of sleep every night
➜ staying hydrated
➜ drinking alcohol moderately — or not at all
➜ practising hand hygiene
➜ and getting regular, appropriate medical checks.
For more advice on colds and flu, we recommend:
Article sources and references
- Bucher A et.al. 2016. Vitamin C in the Prevention and Treatment of the Common Cold. Am J Lifestyle Med. Feb 9;10(3).https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6124957/
- Karsch-Völk M et.al. 2014. Echinacea for preventing and treating the common cold. Cochrane Database Syst Rev. Feb 20;2014(2).https://pubmed.ncbi.nlm.nih.gov/24554461/
- Singh M. et.al. 2011. Zinc for the common cold. Cochrane Database of Systematic Reviews. Issue 2. Accessed May 2023.https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD001364.pub3/full
- Zhao Y et.al. 2022. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database of Systematic Reviews 2022, Issue 8. Accessed May2023.https://pubmed.ncbi.nlm.nih.gov/36001877/
- Thirumdas R et.al. 2021. Role of food nutrients and supplementation in fighting against viral infections and boosting immunity: A review. Trends Food Sci Technol. Apr;110:66-77.https://pubmed.ncbi.nlm.nih.gov/33558789/