Cold: Effects on Health and How to Defend

Winter Diseases: Is It Cold To Blame?

The association between cold and winter ailments is often taken for granted: colds , sore throats , coughs , fever , flu and parainfluenza syndromes are generally more common this season.


In reality, low ambient temperatures, rain, wind, ice and snow are not directly responsible for flu epidemics or other respiratory infections, but they can have a negative impact on our body .

Why do we get sick more in winter?

If from April to October, colds are sporadic, from November to March they become very frequent. On the one hand, the low temperatures , the climatic changes and the wind put a strain on the organism and its natural defenses; on the other hand, in winter we tend to assume a series of behaviors that favor the spread of viruses and bacteria .

Role of Cold

Climatic factors and sudden changes in temperature are not the direct cause of winter ailments, but they can contribute to making the immune system less efficient and can increase the chances of contracting a cold or flu (1). There are, in fact, several other risk factors which, with a cumulative effect, create the ideal conditions for the spread of these infections or for greater susceptibility to contract them.

Closed, crowded and hot places

With the cold, we tend to stay mostly indoors , in heated environments ; often, you go to crowded places or where other people are stationed. In these contexts, the viruses that cause colds or flu find their habitat, continue to proliferate and can spread more easily. To facilitate the infection are the droplets of saliva ( droplets ) that the carriers of viruses and bacteria emit by sneezing, laughing or even just talking, without being aware that they have an incubating disease .

To know moreDroplets: Meaning, Distance, Size and Transmitted Diseases

Thermal stresses

The action of certain viruses and bacteria is facilitated by the temperature changes typical of the autumn and late winter months and by the almost constant temperatures from December to February. This means that from about late October to March , the body’s defenses are called upon to do a super job of repelling external attacks.


In fact, three characteristic elements of this period hinder the action of the hair cells present in the respiratory system , especially in the nose and trachea :

  • Cold: Temperature and humidity can affect the risk of contracting a respiratory infection. A scientific study has shown, in particular, that viruses spread more easily in the presence of a cold and dry climate (2) both outside and inside (due to heating);
  • Climatic variations: often occur within a few hours (or between day and night). Dry wind currents lead to dehydration of the airways, while the arrival of cold and humid air can contribute to respiratory disorders, myalgia, joint pain , headaches and digestive problems ;
  • Thermal changes: they are inevitable when from very hot environments you go out into freezing air and vice versa. In this regard, attention should be paid to increased sweating in the presence of heating: if you pass into a very cold environment, without adapting clothing, it can promote colds.

To take advantage of it, are the viruses – main causative agents of colds, just think of flu and colds – that find the ideal conditions to proliferate and become more aggressive. Only in a minority of cases, however, are bacteria involved , which tend to replicate especially in hot and humid conditions.

There is little outdoors

L ‘ exposure to sunlight positively stimulates all body functions, including mechanisms of thermoregulation and the defense . In winter , the opportunities for being outdoors are reduced: fewer daylight hours and less time spent outdoors mean less exposure to sunlight, useful, among other things, for the synthesis of vitamin D , which contributes to good functioning of the immune system (3).

The important thing is not to stay warm, but to protect yourself adequately when you go out: wear warm but breathable clothes so as not to sweat, avoid the coldest hours of the day, wear a scarf to repair your nose and throat.

People also tend to be less active in cold weather . Although it is not clear exactly whether or how exercise increases immunity to certain diseases, and there is no hard evidence, there are several theories, such as:

  • Improves circulation, allowing white blood cellsto detect and fight an infection faster;
  • Rising body temperatureduring and immediately after a workout can hinder the growth of bacteria, similar to what happens when you have a fever. This rise in temperature can help the body fight infections better;
  • It lowers the levels of stress hormones, reducing the chances of getting sick (4).

The diet is unbalanced and people drink less

In winter, the desire to eat hot and hearty foods and the smaller variety of vegetables lead to a less balanced diet . In this way, we are deprived of the vitamins and mineral salts contained in abundance in fruit and vegetables and essential to support the functionality of our defense system, just when it would be most needed.

With the cold, then, the stimulus of thirst decreases , leading to drink less water . Proper hydration is very important to keep the mucous membranes of the respiratory tract efficient and to eliminate toxins that affect the body.

Consequences on Health

Low temperatures exert a specific action on the body and, in particular, on the respiratory system, with various consequences for health.

Eyelashes become inefficient

The cold acts primarily on the hair cells , that is thousands of microscopic filaments that line the mucous membranes of the respiratory tract (especially the nose and trachea) and repel any infectious agents introduced through the air that penetrates from the outside.

These cells are responsible for the so-called ” mucus- ciliary clearance “: in normal conditions, the cilia of these particular cells move in a precise and cadenced manner, pushing the mucus present in the airways outwards or the digestive system and, with it , even the microorganisms , dust and harmful agents trapped inside it.

In cold weather, this delicate filter and respiratory protection mechanism gets stuck more easily:

  • Both when you are outdoors, due to humidity and lowering of temperature;
  • Both indoors, if overheated and not adequately humidified.

The result is that the mucus with its load of harmful particles cannot be easily expelled from the body and ends up stagnating, favoring the appearance of irritation, infections and inflammation.

To limit the risk, it is good to breathe through the nose , which has a triple function in relation to the inhaled air :

  • Humidifies: thanks to the mucus secreted by the glands; if it were too dry, the air could have an irritating effect on the respiratory tract;
  • Filters: the mucus traps the dust and harmful agents suspended in it; subsequently, the eyelashes with their movements lead them outside;
  • Heats: the nasal cavities are covered with a spongy tissue that contains blood , which has the task of releasing heat.

Did you know that…

The phlegm is a type of mucus that typically develops during an inflammatory process . This secretion is produced by the glands attached to the mucous membrane of the respiratory tract . Unlike the mucus secreted in normal physiological conditions, having the functions of lubricating the walls and facilitating the elimination of external agents that penetrate the body, the phlegm is more abundant , dense and sticky .

The cold weakens the upper airways

Low temperatures cool the nose and throat just as they do other areas of the body (e.g. hands and feet ). As a result, they are irritated and more vulnerable.

The scientific literature (5) has shown that the nose is the ideal environment for the proliferation of many viruses, including rhinoviruses , thanks to its cooler temperature: if the basal body temperature is typically 36.8 ° C, that nasal reaches 33 ° C.

Heating dehydrates the mucous membranes

In addition to facilitating the transmission of infectious agents, closed environments are also risky for another reason: heating . This makes the air dry, thus dehydrating the mucous membranes of the paranasal septa.

Mucous membranes represent one of the main barriers against viruses and bacteria; if they are not properly hydrated, they cannot produce the mucus necessary to trap potential pathogens. Furthermore, when the air is too dry it facilitates the spread of viruses: finding fewer droplets to bind to, the viral particles remain suspended in the air for longer; in fact, the microparticles of water would normally cause them to precipitate. As a result, the risk of contagion increases .

Without forgetting, then, that in winter when the heating is on, to avoid letting in the cold and not to disperse the heat we open the windows less and do not ventilate the rooms sufficiently .

Thermoregulation goes haywire

Transitions from warm to cold environments alter the thermoregulation mechanism, which has the task of keeping the blood at the right temperature, resorting to the production and dispersion of heat. Under normal conditions, the body temperature remains constant around 36.8 ° C, a threshold that guarantees the well-being and normal functions of the organism. If the system’s body temperature varies as it happens in the cold season, the immune defenses weaken.

The hydrolipidic film is altered

The impact with the cold compromises the lipid film, consisting mainly of water and fat, which covers the external surface of the skin and has a protective barrier function.

Who Risks More

Cold: people most at risk


Some people are more vulnerable to colds, get sick more frequently, and / or experience more severe symptoms.

In particular, it is about:

  • Infants and children under the age of 5: they have an immature immune system, therefore less reactive;
  • Elderlyand people with acute or chronic diseases : they are considered more vulnerable to infections of various types, because they are already debilitated.

Even people with unhealthy lifestyles (such as a sedentary lifestyle, cigarette smoking and a little varied and unregulated diet) and those who are very stressed may have defense mechanisms that are not completely efficient. In winter, spending little time outdoors, living in excessively heated environments, living in very polluted cities and excessively covering up also play a negative role.

Overall, these are elements that can reduce the activity of the cells responsible for defending the organism, making it more exposed to the attack of external agents that worsen the ability to adapt to external weather conditions.

Please note

Even young and healthy people can suffer health consequences, sometimes serious, if exposed to excessively low temperatures without the appropriate precautions.

Cold-Favored Diseases

What and what are colds

With colds illnesses and respiratory tract disorders are indicated, often caused by viruses or bacteria , which tend to appear especially in the cold season. In reality, these problems can occur at any time of the year, but their prevalence is much higher during winter and autumn.


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