Natural Treatments for Colds and Flu
The vast majority of upper respiratory tract infections (URTI) are caused by viruses, with cold and flu viruses being the most common. Antibiotics are ineffective against cold and influenza (flu) viruses and should not be used. Over-the-counter cold medications suppress the cold symptoms but they do nothing to speed up the recovery. Therefore, natural treatments for colds and flu are the best option because they have antiviral effects that can help prevent infections, speed up recovery and decrease symptoms.
Elderberry (Sambucus nigra)
Both the European elder (Sambucus nigra) and North American elder (Sambucus canadensis) are used in herbal medicine to fight colds and flu. Traditionally the berries and flowers are both used as a natural treatment for colds and flu. Research shows elderberry reduces symptoms caused by cold1 and influenza viruses2,3. In addition, it has antiviral properties that reduce the length of a cold by two days1. Based on the evidence elderberry is one my top choices for natural treatments for colds and flu.
How does elderberry work?
Elderberry exerts an antiviral activity against numerous respiratory viruses including influenza A4–6 & B6, rhinovirus4 and RSV4. The herb directly blocks the binding and invasion viruses into our cells7 and also inhibits viral replication2,8. Furthermore, elder stimulates the immune system8,9 to help white blood cells fight the infection.
How do I take elderberry?
• Syrup 60 ml/day relieves influenza symptoms3
• Tincture (1:5 conc.) 2-4 ml three times a day 10
• Dried: 3-5g (roughly 1 tsp) 3x/day
How safe is elderberry?
Elderberry extracts are considered safe when used as recommended3. However, safety studies during pregnancy & lactation are lacking 11
Caution: Only the flowers and berries should be used. The bark and leaves contain toxic compounds, called cyanogenic glycosides, that can cause nausea, vomiting, and diarrhea.
2. Zinc – The top mineral for the immune system
Zinc is an essential mineral found in every cell of our body. It has many functions and plays a vital role in our immune system. Research shows this mineral can prevent infections, speed up recovery and decrease symptoms of colds. Zinc supplementation was found to help prevent URTI in infants12, children13,14, and adults15.
Taking zinc during a cold, reduces the duration by roughly 20-42%16–23. Furthermore, zinc reduces the severity common cold symptoms15,21,24–27 including cough, rhinorrhea, nasal congestion, hoarseness and sore throat. In contrast, some studies suggest that zinc treatment does not reduce the severity and duration of the common cold in children28–31.
How does zinc work?
Zinc works by several mechanisms. Like elderberry, zinc blocks the binding the cold virus (rhinovirus)32 to our cells but it also prevents the replication of several viruses including influenza A33, rhinovirus34, SARS35 and RSV36 viruses. Furthermore, zinc prevents the death of cells infected with flu viruses33.
How do I take zinc?
The most common forms of zinc used in the research studies are zinc sulfate, zinc acetate, chelated zinc, zinc citrate and zinc gluconate. Zinc is usually consumed as lozenges, nasal spray or gel. It is effective both preventatively and acutely during infections.
Prevention of Colds:
• Children: 5-15 mg/day lozenges 14,15,21
Treatment of Colds:
• Children: 30 mg/day 21
• Adult: 80 mg/day or 13 mg every 2-3 hours 24,25,27
Find Zinc products
How safe is zinc?
Supplementation with zinc is safe and well-tolerated by children21 and geriatric population37 when taken in the recommended doses. However, do not take long term without consulting a naturopathic doctor. High amounts (>100mg) of zinc for months can cause a copper and iron deficiency38.
3. Andrographis – South Asia natural treatment for colds
Andrographis (Andrographis paniculata) originates in India and Southeast Asia. In India, it is one of the most widely used natural treatments for colds and flu. Research demonstrates that prophylactic use of andrographis prevents the occurrence of the common cold among students39. In addition, andrographis reduces the duration and symptoms of common cold and flu, including nasal congestion, cough, headache, fever, sore throat, ear ache, fatigue and sleep disturbance40–47.
How does andrographis work?
Phytochemicals in the herb called “andrographolides” suppress viral replication by interfering with the production of proteins essential to their replication48. Furthermore, andrographis decreases the production of certain cytokines that contributes to the symptoms49.
How do I take andrographis?
• 200-1200 mg/day reduces symptoms
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How safe is andrographis?
Limited human studies are available but andrographis was found to be safe with only a few mild side-effects50. Caution: Andrographis should not be taken during pregnancy or lactation. An animal study showed that Andrographis intake results in abortion 51.
4. Vitamin C
Vitamin C (ascorbic acid) is an essential nutrient and powerful antioxidant found primarily fruits and vegetables. It provides protection against various diseases including respiratory tract infections. Noble prize winner and researcher Linus Pauling was responsible for making Vitamin C one of the most popular natural treatments for colds and flu. However, based on the research the benefits of vitamin C are a little exaggerated so it may not be the miracle cure for the common cold that people have claimed.
Higher vitamin C intake was found to reduce the occurrence of common cold and other respiratory tract infections52–58. However, some studies showed that supplementing with vitamin C may be ineffective in preventing the occurrence of cold among humans59,60. Supplementing with Vitamin C reduces the duration of cold episodes by as much as 21-59%52,53,55,57,61. Also, it helps provide relief from cold and flu symptoms 62,63.
How does vitamin C work?
Vitamin C boosts the immune system to help fight off viruses. It increases the activity of immune cells (eg. T and NK cells) and enhances the production of interferon64,65. In addition, it can sequester free radicals and decrease inflammation caused by flu virus65,66. Intake of vitamin C inhibits the replication of respiratory viruses to help prevent infection67.
How do I take vitamin C?
Prevention of colds:
• Children: 70 mg/day58
• Adult: >200 – 1000 mg/day54,56,57
Treatment of colds:
• Adult: 1000 mg/day57,63
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How safe is vitamin C?
Although vitamin C is relatively safe, very high intake (>2000 mg/day) may cause gastrointestinal side-effects (eg. diarrhea, nausea, abdominal cramps).57,63
5. Licorice Root
Licorice (Glycyrrhiza glabra)
Licorice (Glycyrrhiza glabra) has been used for thousands of years in herbal medicine for respiratory illnesses because of its antiviral, expectorant and anti-inflammatory actions. In one study, patients suffering from URTI who took a licorice extracts had a shorter hospital stay and lower grade fevers68. Although licorice has less research than some natural treatments of colds its antiviral activity is impressive.
How does licorice work?
The main active ingredients in licorice are glycyrrhizin & glycyrrhizic acid. These antiviral compounds inhibit the viral activity of several respiratory viruses including influenza69, HRSV 70 and SARS-coronavirus71. Glycyrrhizin blocks the attachment of the HRSV72 and influenza virus72 into the host cell and thus reduces infection. Glycyrrhizic acid also has the capacity to bind to the flu virus and therefore alter its activity73.
In addition to its direct antiviral effects, licorice stimulates the immune system and enhances the secretion of interferons (eg. IFN-γ)70,74 that help the body fight viral infections. Also, it reduces the production of harmful pro-inflammatory factors induced by the virus75–77 that cause many of the symptoms. Licorice also has the capacity to inhibit viral replication76,78 including the SARS virus79. In combination with glutamyl-tryptophan, glycyrrhizic acid was also found to be effective against drug-resistant influenza strains80,81.
How do I take licorice?
Treatment of colds and flu:
• Tincture (1:5 in 40% EtOH): 1-3 ml 3x/day
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How safe is licorice?
High doses and/or taking licorice long-term will cause the body to retain sodium 82–87 and lower blood potassium levels88,89 thus elevating blood pressure. It can also cause increased heart rate90, low thrombocytes91 and posterior reversible encephalopathy92,93. Pregnant women should use extreme caution if considering taking licorice94 because it may increase the risk for stillbirth95.
6. Quercetin – A flavonoid for colds and flu
Flavonoids are polyphenolic compounds found in most fruits and vegetables. Certain flavonoids, including quercetin, are great natural treatments for colds and flu because they possess antioxidant, antihistamine, anti-inflammatory and antiviral properties. Quercetin is the most researched of the flavonoids for colds. One human study showed quercetin supplementation led to about 36% reduction of URTI severity and 31% reduction of URTI duration among adults96.
How does quercetin work?
Quercetin activates white blood cells (macrophages) that help the body fight off the infection97. Also, it directly combats the flu virus98–103: it prevents entry of the viruses into the host cell104 and reduces viral replication105–108. Quercetin also protects lungs from damage induced by influenza infection109–111. In addition to the influenza virus, quercetin also prevents replication of cold viruses like RSV112,113 and rhinovirus114,115.
How do I take quercetin?
Treatment of colds:
• Capsules: up to 1000 mg/day
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How safe is quercetin?
Quercetin is “Generally Recognized as Safe” by the US Food and Drug Administration. Since quercetin is found in fruits and vegetables, people may consume up to 1250 mg/quercetin per day in their diet. Therefore, it is assumed that it is safe at this level. However, pregnant women should use caution if considering supplementing with quercetin94.
Probiotics are “good bacteria” that live in our guts that help with digestion and elimination. However these “good bacteria” are one of the overlooked natural treatments for colds and flu. Research supports that certain probiotic strains help both prevent and treat colds and flu116. In addition, probiotics improve various conditions including mood, diabetes, heart disease, and allergies. With all of their benefits probiotic is probably the most important supplement for people to take to improve their health.
Several types of probiotics have anti-viral activity (Table 1.) but the most researched strains are L. acidophilus, L. rhamnosus and L. casei, B. animalis and B. bifidum. Certain probiotics shorten the duration of colds and flu117–123 and reduce the severity of symptoms (including fever, cough, and runny nose)117,124–127.
Some probiotics have been shown to also lower the risk of viral respiratory diseases in children and adult by 20-50%126,128–139. However, some failed to show that probiotics are effective in preventing and treating respiratory diseases140–144 so it’s important to use the correct amounts and strains. Probiotics also enhance the immune response by enhancing the vaccine effects 131,145–148, elevating the production of certain interleukins (eg. IL-2) and cytotoxicity of NK cells118,149.
Table 1. Probiotics with activity against colds and flu
|L. casei (Shirota)
||B. longum subsp. infantis
How do probiotics work?
Probiotics act indirectly to fight viruses by modulating the immune response. Some probiotics activate both humoral and cellular immune response to help fight viruses150–155.
How do I take probiotics?
Prevention/Treatment of colds & flu:
• Children: 1 to 20 billion136,137
• Adults: 50 million to 100 billion CFU126,138,139,146,147,156,117,126,157
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How safe are probiotics?
Probiotic supplementation containing L. rhamnosus GG, B. breve, P. freudenreichii, B. lactis is considered safe and did not cause adverse events in young and elderly subjects158,159. Lactobacillus strains were established to be safe to take during pregnancy94 but other strains have not been researched.
Are there any other natural treatments for colds I should try?
The above list of herbs and supplements are some of the most effective and safe natural treatments for colds and flu, in my opinion. In some cases, you might not have access to these products. Click here to view a list of home remedies for colds and flu you can try as well.
Author & Photographer: Matt Gowan, BSc, ND
All images are copyright of Matt Gowan ©2017
Disclaimer: This content is subject to change. The information is intended to inform and educate; it does not replace the medical evaluation, advice, diagnosis or treatment by a healthcare professional. www.nhpassist.com © 2017 NDAssist Inc. and/or its affiliates. All rights reserved.
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