How Can You Prevent Colds and Flu? Evidence-Based Strategies

Name: How Can You Prevent Colds and Flu? Evidence-Based Strategies
Creator: Sarah Chen, MPH
Published: 2026-02-12T19:50:55.259Z

Science-backed methods to reduce your risk of catching respiratory infections and recover faster when you do.

SCM

Written by Sarah Chen, MPH

MPH, Certified Health Education Specialist (CHES)

DJM

Reviewed by Dr. James Mitchell, MD, FACC

Board-Certified Cardiologist · Cleveland Clinic

Written Feb 12, 2026Reviewed Feb 12, 2026Fact-checked Feb 12, 20263 sources citedMedically Fact-Checked

What Are the Most Effective Ways to Prevent Colds and Flu?

Get your annual flu vaccine, wash hands frequently with soap for 20 seconds, avoid touching your face, maintain 7+ hours of sleep, exercise regularly, and manage stress. These evidence-based strategies collectively reduce your risk of respiratory infections by 40-60%.

Strong EvidenceCochrane systematic reviews provide strong evidence for hand hygiene and influenza vaccination effectiveness.

Hand hygiene remains the single most effective behavioral intervention for preventing respiratory infections. A Cochrane review found that regular handwashing reduced respiratory illness by 16-21%. Alcohol-based hand sanitizers (60%+ alcohol) are effective alternatives when soap and water aren't available. The key moments for hand hygiene are before eating, after touching shared surfaces, after coughing or sneezing, and after being in public spaces.

Annual influenza vaccination is recommended for everyone 6 months and older by the CDC. High-dose and adjuvanted formulations are available for adults 65+ with improved effectiveness. Getting vaccinated by end of October provides optimal protection for peak flu season. Even when vaccine match is imperfect, vaccination reduces the severity and duration of breakthrough infections and significantly lowers hospitalization and death risk.

Regular handwashing reduces respiratory illness by 16-21% per Cochrane review

Do Supplements Help Prevent or Treat Colds?

Zinc lozenges started within 24 hours of symptom onset reduce cold duration by 1-2 days. Vitamin C taken regularly provides modest duration reduction (8% in adults). Vitamin D supplementation benefits those who are deficient. Elderberry extract shows preliminary promise but needs more research. Echinacea evidence is inconsistent.

Moderate EvidenceCochrane reviews support zinc; vitamin D meta-analysis in BMJ; other supplement evidence varies.

Zinc acetate or zinc gluconate lozenges (75+ mg/day elemental zinc) are the best-supported cold treatment supplement. A Cochrane review confirmed that zinc lozenges reduce cold duration by approximately 33% when started within 24 hours. The mechanism involves zinc ions blocking rhinovirus attachment to nasal epithelium. Side effects include nausea and bad taste. Intranasal zinc should be avoided due to risk of permanent anosmia.

Vitamin D supplementation reduced respiratory infections by 12% overall and by 70% in individuals with severe deficiency (below 10 ng/mL) in a BMJ meta-analysis of 25 RCTs. Given that vitamin D deficiency affects an estimated 40% of US adults, supplementation during fall and winter months (1,000-2,000 IU daily) is a reasonable preventive strategy. Elderberry extract (Sambucus nigra) showed reduced duration and severity of influenza in small RCTs, but larger studies are needed.

Zinc lozenges reduce cold duration by approximately 33% per Cochrane review

Vitamin D supplementation reduced respiratory infections by 12% overall in BMJ meta-analysis

Frequently Asked Questions

Does vitamin C prevent colds?

Regular vitamin C supplementation (200+ mg/day) does not prevent colds in the general population but reduces cold duration by about 8% in adults. For people under extreme physical stress (marathon runners, soldiers), regular vitamin C halves cold incidence. Taking vitamin C after symptoms start provides minimal benefit. A balanced diet typically provides adequate vitamin C.

How effective is the flu vaccine?

Flu vaccine effectiveness varies by season depending on how well it matches circulating strains, typically ranging from 40-60% for prevention of medically attended illness. Even in mismatched seasons, vaccination reduces severity, hospitalization risk by 40-70%, and death from influenza. The CDC recommends annual vaccination for everyone 6 months and older.

Should you feed a cold and starve a fever?

This folk wisdom is partially supported. During illness, your body needs additional calories and fluids to mount an immune response. Staying hydrated is critical — warm fluids like broth and tea soothe sore throats and help thin mucus. Eat nutrient-dense foods as tolerated. There is no evidence that restricting food during fever helps recovery; adequate nutrition supports immune function.

Do probiotics prevent colds?

A Cochrane review found that probiotics (particularly Lactobacillus and Bifidobacterium strains) modestly reduce the incidence and duration of upper respiratory tract infections. The effect is small but consistent across studies. Probiotics appear most beneficial in children and in preventing antibiotic-associated complications. Quality and strain specificity matter — not all probiotics are equally effective.

Sources

1.
Physical interventions to interrupt the spread of respiratory viruses — Jefferson T, Del Mar CB, Dooley L et al. Cochrane Database of Systematic Reviews (2023) DOI
2.
Zinc for the common cold — Singh M, Das RR Cochrane Database of Systematic Reviews (2013) DOI
3.
Vitamin D supplementation to prevent acute respiratory tract infections — Martineau AR, Jolliffe DA, Hooper RL et al. BMJ (2017) DOI

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