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NCCIH Clinical Digest

for health professionals

The Common Cold and Complementary Health Approaches: What the Science Says

December 2020

Clinical Guidelines, Scientific Literature, Info for Patients: 
The Common Cold and Complementary Health Approaches

Man with cold symptoms


Oral zinc lozenges may reduce the duration of the common cold when started within 24 hours and taken for a time period of less than 2 weeks. Intranasal zinc has been linked to a severe and permanent loss of smell and should not be used.

Vitamin C

For most people, vitamin C does not prevent colds and only slightly reduces their length and severity. Vitamin C is generally considered safe except when taken in high doses.


Although there is the potential that some preparations of echinacea are more effective than placebo for treating colds, the overall evidence for clinically relevant treatment effects is weak. Results of individual prophylaxis trials consistently show positive (though not significant) trends, although potential effects are of questionable clinical relevance.

Echinacea products vary widely containing different echinacea species, plant parts, and preparations. The many clinical trials of echinacea for colds have also varied widely, in terms of products studied, research methods, and study results.


Currently, not enough research has been conducted to determine whether probiotics may prevent colds, and little is known about their long-term safety.

Nasal Saline Irrigation

Nasal saline irrigation (e.g., using a neti pot) may have benefits for relieving symptoms of the common cold in children and adults, and may have potential benefits for relieving some symptoms of acute upper respiratory infection.

Honey (Buckwheat)

Research suggests that buckwheat honey is superior to placebo for reducing frequency of cough, reducing cough, and improving quality of sleep for children with the common cold. Honey should not be used in children younger than 1 year of age because of the risk of botulism.

Geranium extract (Pelargonium sidoides)

Geranium extract (Pelargonium sidoides) may be helpful in relieving symptoms of acute bronchitis, acute sinusitis, and the common cold in children and adults, but the quality of evidence is low.


A recent Cochrane review concluded that there is insufficient clinical trial evidence regarding the effects of garlic in preventing or treating the common cold.


Some preliminary research suggests that elderberry may relieve symptoms of flu or other upper respiratory infections.

NCCIH Clinical Digest is a service of the National Center for Complementary and Integrative Health, NIH, DHHS. NCCIH Clinical Digest, a monthly e-newsletter, offers evidence-based information on complementary health approaches, including scientific literature searches, summaries of NCCIH-funded research, fact sheets for patients, and more.

The National Center for Complementary and Integrative Health is dedicated to exploring complementary health products and practices in the context of rigorous science, training complementary health researchers, and disseminating authoritative information to the public and professionals. For additional information, call NCCIH’s Clearinghouse toll-free at 1-888-644-6226, or visit the NCCIH website at NCCIH is 1 of 27 institutes and centers at the National Institutes of Health, the Federal focal point for medical research in the United States.


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