Common Cold: everything you need to know about this viral infection
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The common cold is a very common infection of the nose (or more precisely the nasal cavity) and throat, caused by a virus.

Also called viral or acute rhinitis, it causes a sore throat, sneezing, a feeling of a stuffy nose (nasal congestion), and a runny nose.

Causes of colds

The common cold is most often caused by rhinoviruses, which are part of the picornavirus family, which have more than 100 different serotypes.

The body encounters and neutralizes cold viruses several times a year. When a cold appears, it is because the immune system has failed to prevent infection with the virus.

The common cold mainly affects young children because their immune systems are developing and they come into contact with the viruses that cause illness more often.

Cold or flu?

In the case of flu, we feel particularly “bludgeon”, and the whole body feels the effects: great fatigue, muscle pain, fever, headaches, etc.

As for the common cold, it results in “milder” symptoms:

  • runny nose quite abundantly;
  • less intense and rarer fever and headache;
  • pain, fatigue, and weakness are not significant.

For more information, see our Influenza fact sheet.

It should be noted that the common cold can also be confused with respiratory allergies. Consult our sheet for Allergic rhinitis.

Prevalence of colds

Investigations revealed that a normal child could have 6 to 10 episodes of colds per year.

Adults have 2 to 4. With each cold, the body develops immunity to the particular virus that caused the episode. Over time, the body acquires immunity to many of the viruses that cause colds.

From the arrival of autumn until late spring, colds are more frequent. We then spend more time indoors, which contributes to contagion.

Also, during the winter, the air is generally drier in homes, which dries out the mucous membranes of the nose. These become less effective in fighting viruses and preventing the onset of a cold.

In southern countries, colds are more common during the rainy season.

Colds: is it contagious?

The common cold is a contagious disease.

To be able to cause cold, cold viruses must first attach themselves to the mucous membranes of our nose, eyes, or mouth. Unlike the skin, mucous membranes do not form a very tight barrier against microbes. Viruses can reach mucous membranes if you inhale fine contaminated droplets, for example, when a person with cold coughs or sneezes.

The common cold can also be spread through hand contact with an infected person or a contaminated object (glasses, utensils, toys, etc.) when hands are then brought to the mouth, nose, or eyes.

The virus can survive for up to 7 days on inanimate and dry surfaces. The incubation period is very short, varying from a dozen hours (rhinovirus) to a few days.

Possible complications of colds

The common cold itself does not cause complications.

However, it weakens the mucous membranes, which can be secondarily “colonized” by bacteria. This is called bacterial superinfection.

Signs of bacterial superinfection in the sinuses are thickened runny nose and prolonged symptoms over several weeks.

Bacteria can also cause other conditions as a result of a cold. Thus, in children, the most common complication is otitis media.

A persistent cold can also promote the development of sinusitis, pharyngitis, bronchitis, and even, rarely, pneumonia. It can also reactivate the herpes simplex virus, which causes cold sores and genital herpes, weakening the body.

When to see a doctor for a cold?

Generally, it is not necessary to consult a doctor in case of a simple cold.

In most cases, the symptoms disappear in about 1 week.

However, in the presence of any of the following symptoms, which are signs of a complication (otitis, sinusitis, etc.) or a health problem more serious than the common cold, it is better to consult a doctor:

  • intense symptoms that affect the whole body. For example, a fever of 39.5ºC (103 F) or higher, chills or sweats, headache;
  • nasal secretions that persist for more than 10 days, sometimes becoming yellowish and thicker
  • persistent pain in one ear, conjunctivitis, or severe pain in the face or forehead (sinusitis)
  • a cough that persists for more than 7 days after the other symptoms disappear
  • in children: persistent crying or very rapid breathing; blue lips;
  • in children, a cough so severe that they choke or vomit;
  • wheezing
  • the occurrence of a cold in a baby under 4 months, as there is a risk of respiratory failure.

The duration of symptoms is often longer than what is commonly conveyed. The median duration was 11 days in a study of 346 adults with an uncomplicated common cold.

What are the different symptoms of the common cold?

Cold symptoms

The common cold manifests itself with the appearance of the following symptoms:

  • a sore throat, which is usually the very first symptom
  • sneezing and nasal congestion
  • a runny nose (rhinorrhea) requiring frequent blowing of your nose. The secretions are rather clear;
  • mild fatigue
  • watery eyes;
  • mild headaches
  • sometimes a cough;
  • sometimes a little fever (about one degree above normal);
  • wheezing in children with asthma

People at risk of colds

Young children

Most children have their first cold before the age of 1 and remain particularly vulnerable until they are 6 years old, due to the immaturity of their immune system. Being in contact with other children (in kindergarten, daycare, or nursery) also increases their risk of catching colds. With age, colds become less frequent.

People whose immune system is weakened by a drug or disease

In addition, the symptoms are more pronounced in these people.

Risk factors for the common cold


A meta-analysis of 27 prospective studies confirmed that stress was a very significant risk factor.


Smoking produces a local irritant effect on the respiratory tract that decreases local defenses and weakens the immune system.

A recent plane trip

A questionnaire was administered to 1100 passengers on flights between San Francisco and Denver, Colorado. One in 5.20% of people reported having a cold within 5 to 7 days after the flight. Whether or not air was recirculated in the cabin had no effect on the incidence of colds.

Practice intense physical exercises

Athletes who train excessively would be more prone to colds.

How to prevent colds?

It is possible to implement hygiene measures and lifestyle habits that protect you and reduce the risk of catching a cold.

Basic preventive measures against colds

Basic preventive measures

Hygiene measures

  • Wash their hands regularly and teach children to do the same. This is the main way to prevent colds;
  • do not share the personal items (glass, dishes, washcloth, etc.) of a person with a cold, and avoid being too close to them;
  • do not put your hands to your face;
  • cover your mouth and nose with a tissue when coughing or sneezing, or coughing into the crook of your elbow;
  • If possible, stay home when you are sick so as not to contaminate others.


To have good resistance to infections:

  • Exercise and eating well are paramount. Consult our special diet sheet: Colds and flu;
  • get enough sleep;
  • Do not smoke. Tobacco irritates the respiratory tract and increases the risk of infection and cold-related complications;
  • control stress. In times of stress, be attentive and take various measures to relax (moments of relaxation, rest, reduction of activities in case of overwork, sports, etc.).

Measures to prevent complications of colds

To prevent complications from the common cold, a few measures can be put in place: pay particular attention to the prevention of colds, be very vigilant about the basic measures described above; blow your nose regularly, always one nostril after another, with disposable tissues to evacuate secretions; Wash the nasal cavity with saline inserted into the nostrils.

In most cases, the common cold disappears spontaneously. No treatment can get rid of the virus faster.

In fact, the treatment is essentially aimed at making the cold less painful by relieving the symptoms: of sore throat, headache, and nasal congestion.

Since the common cold is caused by a virus, not bacteria, antibiotics have no effect.

In addition, there is no vaccine to prevent colds since, unlike the flu (caused by only a few kinds of viruses), more than 100 viruses can be involved.

All that remains is to let time do its work.

Treatments to cure colds

Drug treatments


This medication (Tylenol®, Tempra®, Acet®) effectively treats headache and low-grade fever. It is important to stick to the dosage, as acetaminophen can cause liver damage if taken too frequently or at higher doses than recommended by the manufacturer. In adults, the maximum dose per day is 4 g. In children, the dose varies according to their weight.


Anti-inflammatory drugs, such as ibuprofen (Advil) or naproxen (Aleve), may also be used to relieve pain and fever.


Aspirin (acetylsalicylic acid) is contraindicated in children: it can cause Reye’s syndrome, a serious disease.


Decongestants in the form of nasal sprays (Dristan®, Otrivin®) are not recommended for children, due to their low effectiveness and adverse effects.

In adolescents and adults, they can be used for up to 3 days. Prolonged use can irritate the fragile mucous membranes of the nose and cause chronic inflammation.

Decongestants taken orally cause fewer problems. As a decongestant, saline can also be used simply by inhalation.

To relieve a clear runny nose, one can use ipratropium nasal spray (Atrovent nasal), which has a drying effect but does not have a decongestant effect.

Cold medicines

Many brands offer cold medicines, which usually combine a painkiller such as ibuprofen or acetaminophen, which also fights fever, and an oral decongestant (pseudoephedrine), sometimes in the form of day/night tablets.

These drugs (Actifed®, Advil cold and sinus, Benylin cold and flu® …) can relieve symptoms,® but do not accelerate healing and are not recommended in children. Respect the dosage.

What about cough syrups?

The common cold is sometimes accompanied by a wet cough or a dry cough. Coughing is not bad in itself, on the contrary. A wet cough helps expel secretions. There is no good evidence that cough syrups, which contain for example dextromethorphan or guaifenesin, are effective.

Other treatments

These products are used to relieve cold symptoms if you have them and to beat them more easily:

Andrographis (Andrographis paniculata)

The authors of a review of 4 randomized, double-blind trials concluded that Andrographis, alone or in combination with Eleutherococcus, is more effective than placebo in treating uncomplicated respiratory infections (cold, flu, pharyngitis)16. The authors of a subsequent review of studies came to the same conclusion.17

One study involved children aged 4 to 11 years, with positive results41. No adverse effects were reported.

Dosage: Take 400 mg of a standardized extract containing 4% to 6% andrographolide (the active ingredient in Andrographis), 3 times daily.

Contraindication: Pregnant women should refrain from Andrographis as it may have abortive effects.


Despite the publication of mixed results, a review concluded that zinc, at high doses of more than 75 mg per day, decreased the duration of the common cold but not its severity.

It must be administered within the first 24 hours and very often causes nausea and a bad taste in the mouth at this dose.

Echinacea (Echinacea sp)

Two meta-analyses each involving fifteen trials concluded that, despite some inconclusive results, treatment with echinacea slightly reduced the intensity of cold symptoms (congestion, runny nose, sore throat, headache, weakness, and chills) and reduced their duration by an average of 1.4 days.

However, one clinical trial found no significant decrease in symptoms.57

Dosage: If a person still wants to try it, it is important to take echinacea at the first sign of a cold. Some therapists even recommend a loading dose. P

Vitamin C (ascorbic acid)

In recent decades, many studies have looked at the effectiveness of vitamin C in reducing cold symptoms. A meta-analysis65 concludes that vitamin C is not effective.

Curiously, these authors still say that given the low cost and the absence of toxicity, a person can still try it.

Garlic (Allium sativum)

ESCOP recognizes the use of garlic to treat respiratory tract infections. L

The results of a double-blind placebo clinical trial gave weight to this traditional use: among the 146 subjects treated, those who took a garlic capsule for 12 weeks (between November and February) had fewer colds than those in the placebo group.

In addition, when they had a cold, their symptoms resolved more quickly.

Peppermint (Mentha x piperita)

Commission E and ESCOP recognize the use of peppermint essential oil for the relief of coughs and colds, internally or externally.

Dosage: it is possible to take it internally, or in the form of nasal ointment. See the Peppermint sheet.

Plantain (Plantago major)

Since 1985, the German Commission E has approved the medicinal use of lanceolate plantain to treat infections and inflammations of the respiratory tract internally.

In Europe, the plant is an ingredient in several expectorants and cough-suppressant herbal preparations.

Dosage: take as an infusion, tincture, or fluid extract. See the Plantain fact sheet for more information.

Licorice (Glycyrrhiza glabra)

Licorice root is part of a multitude of traditional medicinal preparations. Commission E recognizes its use to treat inflammation of the respiratory tract.

Some substances contained in licorice would exert an antiviral effect. Dosage It is used internally, in the form of dried root or total extract. See the Licorice sheet for more information.

Black elderberry (Sambucus nigra)

Commission E approves the use of this plant to treat the common cold. It would be particularly effective in lowering fever, according to the British Herbal Compendium.

Several trials have shown the effectiveness of elderberries in reducing flu symptoms, including cough and nasal congestion, which are the key symptoms of the common cold.

Note: Black elderberry (Sambucus nigra) should not be confused with white elderberry (Sambucus canadensis).

White Willow (Salix alba)

Commission E recognizes its use in treating diseases accompanied by fevers, rheumatism, and headaches.


Traditionally, several herbs have been used to relieve cold symptoms, such as sore throat and cough. These include isatis, angelica, German chamomile, catnip, eucalyptus, ginger, and thyme. Consult our corresponding sheets to know how to use them.


It can help reduce the intensity and duration of symptoms, but no large-scale scientific studies have evaluated its effectiveness. See our Acupuncture sheet.


Some changes in diet can help strengthen the immune system, thus speeding up healing. See the special diet sheet: Colds and flu.


Based on their clinical experience, some doctors argue that daily consumption of cow’s milk and dairy products opens the door to repeated infections, such as colds, ear infections, and sinusitis.

According to them, milk would contribute to the accumulation of toxins in tissues. Occasional use would not be a problem. However, this opinion is not shared by the majority of physicians.

In addition, most nutritionists do not advise against dairy products in case of repeated colds.

Dr. Andrew Weil recommends including Asian mushrooms (such as maitake, cordyceps, shiitake, and reishi) in his diet at the first symptoms of the common cold.35 These mushrooms would help strengthen the immune system.

Chinese Pharmacopoeia

Yin Qiao San preparation was created to combat infectious diseases in children. It should be taken as soon as cold symptoms appear.

The preparation of Yu Ping Feng San (Wan) is indicated for people who suffer from repeated colds, for children who go from colds to otitis or other respiratory infections, and for those who have allergy problems.

A meta-analysis studied 14 studies involving 2,440 patients evaluating different Chinese herbal preparations. Despite the questionable methodology of the studies, the authors concluded that the Chinese pharmacopeia could reduce the duration of the common cold, but could not recommend any particular preparation.56

For other ways to treat colds with Chinese pharmacopeia, see Fighting Colds the Chinese Way.

“Grandma’s Remedies”

The following folk remedies are recommended by doctors or have some scientific basis36 :

Chicken broth

To help clear the sinuses while promoting antibacterial and antiviral activity, take the hot chicken broth, seasoned with onion, garlic, cayenne pepper, or hot peppers.

Inhalation of eucalyptus (Eucalyptus Radiata or E. globulus)

To relieve, clear, and disinfect the respiratory tract, inhale eucalyptus fumes for 15 minutes, 3 times a day in the acute phase, and 1 time before bedtime when the cold subsides.

Honey and lemon

The combination of honey and lemon helps relieve throat irritation. Honey could also inhibit the reproduction of bacteria in the throat.

Ginger herbal tea (Zingiber officinale).

This classic “warming” herbal tea helps relieve cold symptoms. Infuse 1 tablespoon of grated fresh ginger in 250 ml of boiling water for 10 minutes.

Cinnamon tea (Cinnamomum zeylanicum)

Infuse 1 tablespoon of cinnamon powder and 2 cloves of garlic in 250 ml of boiling water for 20 minutes. Flavor with a little honey and lemon. Drink 1 to 3 cups daily.

Lemon balm tea (Melissa officinalis)

This herbal tea with antiviral properties helps reduce fever associated with colds and flu. Infuse for 10 minutes 1 tablespoon of dried lemon balm leaves in 250 ml of boiling water.

Slippery elm tea (Ulmus rubra)

Slippery elm contains mucilage that relieves throat irritation. Mix 1 tbsp slippery elm powder with 200 ml of water and a little honey. Gargle lightly and swallow in small gulps.

Herbal tea of perfoliate eupatorium (Eupatorium perforliatum) and yarrow (Achillia millefolium)

Make herbal tea with 1/2 tsp eupatory and 1/2 tsp yarrow; Infuse for 30 minutes in 1 cup (250 mL) of water. The combination causes abundant sweating and stimulates the immune system. Drink as hot as possible.

Total cocktail of the West Indies

This traditional Caribbean recipe has proven itself for generations: mix 125 ml of lemon juice, 2 tablespoons of vinegar, 1 clove of crushed garlic, 1 tsp of grated fresh ginger, and a little cayenne pepper. Swallow all at once.

Comfort care during a cold

The following measures are recommended by doctors. It is best to apply them at the first signs of colds or colds:

  • get plenty of rest to support the immune system;
  • drink at least 2 liters of water and other drinks a day to avoid dehydration (hot drinks, such as herbal teas and soup, provide a lot of comfort);
  • To relieve sore throat, gargle with warm salt water several times a day;
  • decongest the nose (including in children);
  • take hot showers or hot baths;
  • stay warm, but do not overheat the bedroom, which dries out the air and makes breathing more difficult;
  • Use a humidifier if needed. According to Health Canada, it is good to keep the humidity of residences at 50% during the summer and 30% during the winter (a hygrometer can measure the humidity level)3 ;
  • To relieve skin irritation around the nostrils, apply a little petroleum jelly to the sensitive area.

To decongest the nose, place a few drops of saline solution in each nostril. To facilitate application, lie on your back and tilt your head back. There are also vaporizers that make it easy to apply. Clean the inside of the nostrils with a swab (cotton swab). Put a few drops of saline in each nostril again. Blowing your nose or, in the case of a young child, sucking mucus with a nasal pear.

This technique could also help relieve hay fever.

Saline solutions are easily found in pharmacies (e.g. Salinex®, Hydrasense®). You can also prepare one yourself.

Homemade saline solution recipe: Dissolve 1/2 tsp salt in 8 oz (240 mL) boiled and cooled water. It is very important to respect this proportion, otherwise, there is a risk of irritating the mucous membranes of the nose; store the solution in a clean bottle with a dropper; Redo a new solution every 3 days.

Certain herbal products as well as supplements can reduce the risk of catching a cold. They essentially work by strengthening the body’s immune defenses.

In the prevention of colds

Vitamin C for athletes

In athletes, vitamin C in the form of supplements helps prevent colds related to overtraining syndrome.

A meta-analysis shows a 50% decrease in the risk of catching a cold in subjects who took vitamin C for 3 to 8 weeks before a race or an intense period of another type of activity13.

Dosage: Take 250 mg to 1 g daily, starting about 3 weeks before the period of intense exercise.

Vitamin C for the general population

In the general population, daily vitamin C supplements may not be effective in preventing colds, according to a meta-analysis of 30 trials and 11,350 people.

Ginseng (Panax ginseng)

Studies indicate that, in conjunction with a flu vaccine, ginseng reduces the incidence of acute respiratory infections, including the common cold.

In people who were not vaccinated against the flu, a study published in 2005 found that ginseng reduced the number of colds only modestly (-13%).

Dosage: Take 100 mg to 200 mg of a standardized extract (4% to 7% ginsenosides), 2 times daily. See the Ginseng fact sheet for more information.

In Canada, the remedy COLD-fX®, based on North American ginseng root, is widely used to prevent colds. A review concluded that although several trials suggest a reduction in the number of colds and the duration of symptoms, scientific data are not sufficient to certify the preventive efficacy of COLD-fX®.


A randomized study evaluated the effectiveness of a mixture of probiotics (Lactobacillus Plantarum (DSM 15312) and Lactobacillus paracasei (DSM 13434)) taken in preventing colds. In the group receiving probiotic supplements, the risk of catching a cold was 55% compared to 67% in the control group, and the duration of colds was reduced by more than 2 days.

A study conducted in 326 children aged 3 to 5 years showed the preventive efficacy of the probiotic Lactobacillus acidophilus alone or in combination with Bifidobacterium animalis, administered 2 times a day for 6 months. Compared to placebo, probiotics reduced the incidence of fever and cough by more than half, and the incidence of nasal congestion by 30% (60% with the combination of the two probiotics).

Andrographis (Andrographis paniculata)

Andrographis may be effective in preventing colds.

A placebo study involved 107 people with an average age of 18 years. Some of the participants took 2 times a day 100 mg of an extract standardized to 5.6% andrographolide. Subjects taking Andrographis extract were 2 times less likely to contract a cold than those taking a placebo.

However, this benefit of Andrographis only manifested after 2 months of treatment. No adverse effects were reported.

Echinacea (Echinacea sp)

The effectiveness of echinacea in preventing colds appears to vary, according to studies8-11,48,49. It could depend on the type of echinacea preparation used and also the type of virus that causes the common cold.

According to pharmacist Jean-Yves Dionne, echinacea loses its preventive effectiveness after 3 months of use.


Taking glutamine before or immediately after strenuous exercise may also help prevent overtraining syndrome, but only one study looked at this use.

Astragalus (Astragalus membraceanus or Huang qi)

The root of this plant is used in Traditional Chinese Medicine to increase the body’s resistance to viral infections.

Some studies conducted in China tend to show that astragalus could strengthen the immune system and thus prevent colds.

It would also reduce cold symptoms once it is installed and speed healing.

Image Credit: Image by katemangostar on Freepik

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