Cold and Flu

Understanding Cold and Flu

The common cold and influenza are both contagious viral infections of the respiratory tract, but flu is usually more severe. A cold is a mild-to-moderate, self-limited upper respiratory infection, most often caused by rhinovirus.^[1] Influenza is caused by influenza viruses and affects the upper and lower respiratory tract.^[2]

Common symptoms

A cold typically causes malaise, nasal congestion, runny nose, sneezing, sore throat, cough, and occasionally fever and headache.^[1] Influenza brings a runny nose, high fever, cough and sore throat, and most healthy people recover fully within a few days.^[2]

Flu tends to come on suddenly and feel worse than a cold, with more body aches and tiredness.

Causes and risk factors

Many viruses cause colds, and rhinovirus is the most common.^[1] Influenza spreads through respiratory droplets from coughing, talking and sneezing, and by touching contaminated surfaces and then the nose or eyes. A person can pass it on before symptoms start and for 5 to 7 days after infection.^[2]

Complications of flu such as pneumonia are more common in young children, older adults, pregnant people and people with weakened immune systems.^[2] Rhinovirus colds have also been implicated in asthma and COPD flare-ups.^[1]

How it is diagnosed and treated conventionally

Colds are diagnosed from symptoms and are usually self-limited. Rapid flu tests have limited sensitivity and false negatives are common, so a physician may diagnose flu from symptoms and local flu activity.^{[1, 2]} Vaccination is the key strategy for reducing the illness caused by influenza.^[2]

Antibiotics do not treat viral infections, and unnecessary antibiotic prescribing for upper respiratory infections is common.^[1] For flu, an antiviral such as oseltamivir shortened time to symptom relief by about a day in a pooled analysis of nine trials in adults. It reduced lower respiratory complications and hospital admissions but increased nausea and vomiting.^[3] Whether an antiviral is right for you is a decision for your physician.

Why Cold and Flu calls for a whole-person approach

Whether you catch a virus, and how hard it hits, depends on more than the virus. Exposure, vaccination, nutrition, general health and other conditions all play a part.

Looking at those factors alongside medical care is reasonable, and it does not replace vaccination or treatment of flu. A 2005 review of Cochrane reviews concluded that most non-antibiotic cold remedies are probably not effective, so the research below should be read with that caution.^[4]

Exposure and hygiene

Flu spreads by droplets and by touching soiled surfaces.^[2] Staying home when sick, covering coughs and washing hands are common-sense steps that follow from how it spreads, though we cite no trials of them here.

Vaccination

Vaccination is described as the key strategy for reducing the illness that influenza causes.^[2] Ask your physician or pharmacist about the flu vaccine each season.

Nutrition and vitamin D

An individual-participant meta-analysis of 25 trials found that vitamin D supplements reduced the risk of acute respiratory infection overall. The benefit was strongest in people who were very deficient and who took it daily or weekly.^[5] Whether to test or supplement is a question for your physician.

Other health conditions

Colds can aggravate asthma and COPD.^[1] Flu complications are more common in high-risk groups such as young children, older adults, pregnant people and people with weakened immune systems.^[2] Keeping chronic conditions well controlled is part of protecting yourself in cold and flu season.

Acupuncture for Cold and Flu

What the research shows

We found no systematic reviews or good trials of acupuncture for the common cold or influenza. There is no research evidence that acupuncture prevents these infections or shortens them.

Because a cold is self-limited and usually clears within days, feeling better after any treatment cannot be credited to that treatment without a comparison group.^[1]

How acupuncture may work

No mechanism by which acupuncture would act on cold or flu viruses has been shown. Any role is limited to general relaxation and comfort, and that is not supported by cold or flu studies.

What treatment involves

Treatment uses fine, sterile, single-use needles placed at points on the head, neck, arms and legs, usually left in place for about 20 to 40 minutes. A course is typically several visits, and we reassess progress with you during it. If you have a fever, wait until you are well and have been seen by a physician if needed.

Serious problems are rare. In prospective studies, about 9 in 100 patients had a minor reaction such as brief bleeding, soreness or redness at a needle site, and serious events occurred in about 1 in 10,000 patients.^[6] Tell the practitioner first if you have a bleeding disorder, take blood thinners, are pregnant, or have a pacemaker (relevant to electroacupuncture).

Ayurvedic medicine for Cold and Flu

The Ayurvedic view

In Ayurveda, a cold with congestion and mucus is described as Pratishyaya, and is traditionally linked to excess Kapha with disturbed Vata. Flu-like illness with fever is described as Jvara. These are traditional categories used to plan supportive care, not biomedical diagnoses.

Therapies that may be used

Care is individualized and may include:

• Warm, easily digested food and fluids, rest, and regular sleep
• Herbs traditionally used for cough and congestion, such as tulsi, ginger, licorice root and kalmegh (Andrographis paniculata), prescribed individually
• Steam inhalation and gentle warm oil massage of the chest and back

Panchakarma procedures are not appropriate during pregnancy, acute illness, fever or frailty, so they are not used during a cold or flu. Transdermal medication therapy, in which an herbal preparation is applied to the skin, may also be used; we found no studies of it in colds or flu.

What the research shows

The research on Ayurveda for cold and flu is limited. A PubMed search found no trials of Ayurvedic treatment programs. Kalmegh (Andrographis) is a traditional Ayurvedic herb, and one placebo-controlled trial of 300 people with an uncomplicated cold tested a standardized extract of it. Symptom scores were lower than with placebo on day 3 but not on day 5 or day 7, so the effect was early and short-lived.^[7]

Reviews of other Ayurvedic herbs such as tulsi describe laboratory and general findings and not trials in colds, so no benefit can be claimed for them. Because colds are self-limited, improvement after any remedy cannot be credited to it without a comparison group.^[1]

Product quality also matters. About one fifth of Ayurvedic products bought online contained detectable lead, mercury or arsenic, so herbs should come from tested sources.^[8]

Herbal medicine for Cold and Flu

Herbs and formulas that have been studied

Herbs studied for cold and cough include Andrographis, Pelargonium sidoides, Echinacea, and ivy, primrose and thyme preparations.^{[9, 10]} Chinese herbal formulas have been studied for influenza.^[11]

What the research shows

A meta-analysis of 34 randomized trials (7,083 participants) of herbs for cough from upper respiratory infection, mostly placebo-controlled with low risk of bias, found Andrographis and ivy, primrose and thyme preparations were better than placebo for cough. It rated Pelargonium as moderate and Echinacea as limited. Its search ended in 2012, and cough is a symptom of colds, not the infection itself.^[9]

A Cochrane review of Echinacea found no clear benefit for treating colds. Prevention trials showed non-significant trends toward fewer colds, and the authors judged any effect to be of questionable clinical relevance.^[10]

For influenza, a Cochrane review of 18 trials of Chinese herbs (2,521 participants) found mostly poor-quality studies. The trials compared herbs with antiviral drugs rather than placebo. Most herbs performed similarly to the drugs, few were superior, and the authors called the evidence weak.^[11] A review of herbs with antiviral activity against influenza describes laboratory findings and says more studies are needed before these compounds can be used as medicines.^[12] That is laboratory evidence, not proof of benefit in people.

Safety and herb-drug interactions

Herbs are active substances and can interact with medicines. A review of case reports describes serious bleeding or clotting problems when warfarin was combined with herbs including dang gui (Angelica sinensis), dan shen, ginger, ginseng and Boswellia.^[13] A broader review notes interactions with ciclosporin and tacrolimus after St John's wort, which matters if you take immune-suppressing medicines.^[14] Tell us about all your medicines and supplements, including over-the-counter cold remedies.

In one study, about one fifth of Ayurvedic products bought online contained detectable lead, mercury or arsenic.^[8] Herbal and dietary supplements are also a recognized cause of liver injury.^[15] Herbs should come from tested sources and be prescribed individually. Tell us if you are pregnant or breastfeeding, have liver or kidney disease, or have surgery planned.

Translating traditional medicine into modern biological language

The links drawn here are interpretation, not equivalence. Chinese medicine describes colds as wind-cold or wind-heat invading the body's surface, and uses herbs chosen to match the pattern. Researchers studying such herbs look at antiviral activity against influenza proteins and at host-cell signaling pathways, mostly in laboratory studies.^[12]

Ayurveda's Kapha, described as mucus and heaviness, resembles the congestion and phlegm of a cold. No study has shown that a TCM pattern or a dosha corresponds to a specific biological process in colds or flu.

How this care fits with your medical care

Integrative care for colds and flu is complementary. It does not replace the flu vaccine, antiviral medicine or your physician's advice, and nothing here is a way to prevent or treat flu in place of them.

Keep your physician, and do not stop or change prescribed medicines without your prescriber. We do not diagnose the illness. Seek medical advice early if you are in a high-risk group, which includes young children, older adults, pregnant people and people with weakened immune systems.^[2] People with chronic heart or lung disease should also ask their physician early. Please bring a full list of medicines and supplements, and tell us if you are currently feverish or unwell.

When to seek urgent medical care

Most colds and many flu cases settle at home, but some symptoms signal complications such as pneumonia.^[2]

• Trouble breathing, shortness of breath or chest pain
• Confusion, extreme drowsiness or fainting
• A high fever that persists, or a fever that returns after improving
• Symptoms that improve and then get much worse
• Cold symptoms lasting longer than about 10 days without improvement
• Illness in a high-risk person, such as an infant, older adult, pregnant person or someone with a weakened immune system

Call 911 or go to the nearest emergency department for severe symptoms.