Colds and Flus

Related Term

Upper Respiratory Infections; Influenza

A cold is an infection that can bother the nose and throat. It is caused by a virus. Influenza (flu) is a viral infection that may cause problems with breathing. The flu can make you a little sick or very sick. Sometimes it can lead to death.

Both the cold and the flu can cause problems that get in the way of daily tasks. Both are treated with home care and over the counter drugs. But the flu may need prescription drugs. A flu shot can also help stop you from getting the flu. Some people turn to natural therapies to treat health problems and lower the risk of a bacterial infection.

Natural Therapies

Likely Effective

Possibly Effective

May or May Not Be Effective

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Herbs and Supplements to Be Used With Caution

Talk to your doctor about all herbs or supplements you are taking. Some may cause problems with your treatment plan or health conditions. Some supplements discussed here have certain concerns such as:

  • Ginseng may change blood sugar and blood pressure. Talk to your doctor if you have diabetes or high blood pressure.
  • Too much vitamin C may be linked to kidney stones. Do not take vitamin C with iron supplements. Use care when taking vitamin C and acetaminophen.
  • Zinc in high doses may result in side effects that range from nausea and vomiting to reduced immune function or reduced iron function. Zinc nasal gel may result in loss of smell.


Essential Oils

A1. Kehrl W, Sonnemann U, Dethlefsen U. Therapy for acute nonpurulent rhinosinusitis with cineole: results of a double-blind, randomized, placebo-controlled trial. Laryngoscope. 2004;114:738-742.

A2. Tesche S, Metternich F, Sonnemann U, et al. The value of herbal medicines in the treatment of acute non-purulent rhinosinusitis: Results of a double-blind, randomised, controlled trial. Eur Arch Otorhinolaryngol. 2008 Apr 25.

A3. Paul IM, Beiler JS, King TS, Clapp ER, Vallati J, Berlin CM. Vapor rub, petrolatum, and no treatment for children with nocturnal cough and cold symptoms. Pediatrics. 2010;126(6):1092-1099.


B1. Coon JT, Ernst E. Andrographis paniculata in the treatment of upper respiratory tract infections: a systematic review of safety and efficacy. Planta Med. 2004;70:293-298.

B2. Goel V, Lovlin R, Barton R, et al. Efficacy of a standardized echinacea preparation (EchinilinTM) for the treatment of the common cold: a randomized, double-blind, placebo-controlled trial. J Clin Pharm Ther. 2004;29:75-84.

B3. Poolsup N, Suthisisang C, Prathanturarug S, Asawamekin A, Chanchareon U. Andrographis paniculata in the symptomatic treatment of uncomplicated upper respiratory tract infection: systematic review of randomized controlled trials. J Clin Pharm Ther. 2004 Feb;29(1):37-45.

B4. O'Neil J, Hughes S, Lourie A, et al. Effects of echinacea on the frequency of upper respiratory tract symptoms: a randomized, double-blind, placebo-controlled trial. Ann Allergy Asthma Immunol. 2008;100:384-388.

B5. Saena RC, Singh R, et al. A randomized double blind controlled clinical evaluation of extract of Andrographis paniculata (KalmCold) in patients with uncomplicated upper respiratory tract infection. Phytomedicine. 2010 Mar;17(3-4):178-185.

B6. Barrett B, Brown R, et al. Echinacea for treating the common cold: a randomized trial. Ann Intern Med. 2010 Dec 21;153(12):769-777.

B7. Karsch-Völk M, Barrett B, et al. Echinacea for preventing and treating the common cold. Cochrane Databse Syst Rev. 2014 Feb 20;(2):CD000530.


C1. Josling P. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Adv Ther.2001;18:189-93

C2. Predy GN, Goel V, et al. Efficacy of an extract of North American ginseng containing poly-furanosyl-pyranosyl-saccharides for preventing upper respiratory tract infections: a randomized controlled trial. CMAJ. 2005 Oct 25;173(9):1043-1048.

C3. Tubelius P, Stan V, Zachrisson A, et al. Increasing work-place healthiness with the probiotic Lactobacillus reuteri: A randomised, double-blind placebo-controlled study. Environ Health. 2005 Nov 7. [Epub ahead of print]

C4. McElhaney JE, Goel V, et al. Efficacy of COLD-fx in the prevention of respiratory symptoms in community-dwelling adults: a randomized, double-blinded, placebo-controlled trial. J Altern Complement Med. 2006 Mar;12(2):153-157.

C5. Lizogub VG, Riley DS, Heger M. Efficacy of a pelargonium sidoides preparation in patients with the common cold: a randomized, double blind, placebo-controlled clinical trial. Explore (NY). 2007 Nov-Dec;3(6):573-84.

C6. Prasad AS, Beck FW, Bao B, et al. Duration and severity of symptoms and levels of plasma interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, and adhesion molecules in patients with common cold treated with zinc acetate. J Infect Dis. 2008 Feb 15.

C7. Rautava S, Salminen S, Isolauri E. Specific probiotics in reducing the risk of acute infections in infancy—a randomised, double-blind, placebo-controlled study. Br J Nutr. 2008 Nov 6.

C8. Cox AJ, Pyne DB, et al. Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. Br J Sports Med. 2010 Mar;44(4):222-226.

C9. Hemilä H. Zinc Lozenges may shorten the duration of colds: a systematic review. Open Respiratory Medicine Journal 2011;5:51‐58

C10. Van Puyenbroeck K, Hens N, et al. Efficacy of daily intake of Lactobacillus casei Shirota on respiratory symptoms and influenza vaccination immune response: a randomized, double-blind, placebo-controlled trial in healthy elderly nursing home patients. Am J Clin Nutr. 2012 May;95(5):1165-1171.

C11. Science M, Johnstone J, et al. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. CMAJ. 2012 Jul 10;184(10):E551-E561.

C12. Lee CS, Lee JH, et al. Preventive effect of Korean red ginseng for acute respiratory illness: a randomized and double-blind clinical trial. J Korean med Sci. 2012 Dec;27(12):1472-1478.

C13. Singh M, DAS RR. Zinc for the common cold. Cochrane Database Syst Rev. 2013 Jun 18;(6):CD001364.

C14. Hao Q, Dong BR, et al. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev. 2015 Feb 3(2):CD006895.

C15. Hemilä H, Chalker E. The effectiveness of high dose zinc acetate lozenges on various common cold symptoms: a meta-analysis. BMC family practice. 2015 Feb 25;16:24.

Traditional Chinese Medicine

D1. Wu T, Zhang J, Qiu Y, Xie L, Liu GJ. Chinese medicinal herbs for the common cold. Cochrane Database Syst Rev. 2007 Jan 24;(1):CD004782.

D2. Wang C, Cao B, Liu QQ, et al. Oseltamivir compared with the Chinese Traditional Therapy maxingshigan-yinqiaosan in the treatment of H1N1 influenza: a randomized trial. Ann Intern Med. 2011;155(4):217-225.

D3. Li G, Cai L, et al. Compound formulas of traditional Chinese medicine for the common cold: systematic review of randomized, placebo-controlled trials. Altern Ther Health med. 2015 Nov-Dec;21(6):48-57.


E1. Martineau AR, Jolliffe DA, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017 Feb 15;356:i6583.

E2. Murdoch DR, Slow S, et al. Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: the VIDARIS randomized controlled trial. JAMA. 2012 Oct 3;308(13):1333-1339.

E3. Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013 Jan 31;(1):CD000980.

E4. Ginde AA, Blatchford P, et al. High-dose monthly vitamin D for prevention of acute respiratory infection in older long-term care residents: a randomized clinical trial. J Am Geriatr Soc. 2017 Mar;65(3):496-503.

Last reviewed February 2019 by EBSCO NAT Review Board Richard Glickman-Simon, MD

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