7 Signs of Pneumonia (Lung Infection)

Pneumonia is a respiratory disease that affects the normal functioning of the lungs. The intensity of pneumonia may vary from mild to severe in different patients. Severe cases of pneumonia can be fatal without prompt treatment. The lung tissue is prone to get infections like pneumonia due to its constant exposure to air that enters the lungs through each breath. Various pollutants and microbes present in the air can get easy access to the lung tissue via the breathing process. Apart from the lungs, other tissues of the respiratory pathway may also get infected or inflamed by such airborne microbes.

About Pneumonia

Our environment is teeming with a variety of microbes such as bacteria, viruses, and fungi. Some of the microbes are also present in the air. With each breath, there is a high chance of these microbes entering the respiratory passages and reaching the lung tissue. However, not all microbes that we inhale harm the air passages or the lungs. And not everyone who gets exposed to a specific microbe gets the disease.

Despite the high chance of countless microbes reaching the lungs through the airways, very few manage to do so. This is due to the defense mechanisms that are present in different regions of the airways. These defense mechanisms work to filter or trap particles and microbes that enter the air passages with each breath.

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Examples of such defense mechanisms in the airways include the presence of nasal hairs in the nostrils, mucus in the airways, and microscopic hairs (known as cilia) in the bronchi. These defenses prevent most of the particle and microbes that enter the respiratory tract from reaching the lung tissue. The lung tissue itself has an immune defense mechanism that can neutralize any microbial pathogens that may reach the lungs.

Despite the multiple defense mechanisms in the respiratory system, sometimes microbes do manage to reach the lung tissue and cause infection. Pneumonia is caused by a bacterial infection of the lung tissue, and is typically seen in people with a weak or immature immune system (such as the very young and the elderly). People with pre-existing diseases of the lung are also more likely to develop pneumonia.

Infection of the lungs may also occur via the bloodstream. Pathogenic bacteria from other regions of the body may be able to reach the lungs through the bloodstream and cause infections. However, this is a relatively uncommon route for developing pneumonia.

A person suffering from pneumonia can spread the disease through airborne water droplets released during coughing or sneezing. These infectious air droplets can easily find their way into the respiratory tract of a healthy individual who is standing nearby. The risk of acquiring pneumonia infection is relatively higher in healthcare settings such as a hospital.

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How To Spot Pneumonia

Both upper and lower respiratory tract infections are common occurrences in the lives of people around the globe. The signs and symptoms of pneumonia are commonly mistaken for other respiratory tract infections (especially lower respiratory tract infections) that are more common in a population. However, the symptoms of pneumonia are relatively more severe compared to other common respiratory tract infections.

Due to the highly contagious nature of pneumonia, one should not delay seeking medical advice if pneumonia is suspected. Occurrence of symptoms such as difficulty in breathing, bluish skin color, and blood in sputum should prompt emergency medical treatment. Some forms of pneumonia may progress very rapidly and can be fatal without prompt treatment.


Wet or productive cough is one of the most common symptoms of pneumonia. Productive cough refers to the presence of mucus in the coughed out sputum. The mucus and other secretions come from the lower respiratory passages, and may range in color from white to brownish or yellow. Blood may also be coughed out in some severe cases of pneumonia. The coughing of blood is technically referred to as hemoptysis.


The color, odor and taste of the sputum varies a lot depending on the type and severity of pneumonia. The color of the sputum in pneumonia may be clear, brown, yellow, green, rust-colored or reddish (due to blood). Green colored sputum is usually seen in infection with Pneumococcal bacteria and Haemophilus pseudomonas. Infection with Streptococcus pneumoniae usually causes the appearance of rust-colored sputum. Infections with anaerobic bacteria may also cause foul-tasting and foul-smelling sputum.

Shortness of breath

Shortness of breath is a common occurrence in many cases of pneumonia. The severity of the condition may increase when lying down or with increased physical activity. In severe cases of pneumonia, low oxygen levels in the blood may cause shortness of breath even during sedentary activities.

Chest pain

Chest pain in pneumonia is caused by inflammation of the lungs. Pain in the chest may also be due to muscular strain in the chest wall, caused by prolonged labored breathing and coughing. The pain is especially bad during the inhalation phase of the breathing cycle. The intensity of pain depends on the severity of pneumonia. Severe coughing may also result in abdominal pain.

Abnormal breathing sounds

The rate of breathing is abnormally high (more than 18 breaths every minute) in pneumonia. Such rapid breathing is technically referred to as tachypnea. In addition to rapid breathing, abnormal breathing sounds such as wheezing, rhonchi, and rales are also present. Inhalation or exhalation of breath produce a rattling, whistling or crackling sound.

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Pneumonia in most individuals may also be accompanied by an increase in body temperature (above 100.4 °F or 38 °C), chills, and sweating. Conversely, pneumonia in the elderly may cause hypothermia, resulting in the dropping of body temperature below 95 °F or 35 °C.


Fatigue is a common occurrence in pneumonia due to suboptimal functioning of the lungs. Compromised lung function leads to lower oxygen and higher carbon dioxide levels in the blood. Since oxygen is essential for the production of energy in muscles, a low oxygen level in the blood leads to muscular fatigue. Physical exertion worsens the feeling of fatigue. Muscular pain may also be present.

Other signs and symptoms

Pneumonia may also be accompanied by nausea, vomiting, diarrhea, headache, and alteration in mental status. Heart rate is typically higher than normal (tachycardia), but can also be lower than normal (bradycardia) in some cases. Lack of oxygen in the blood may cause bluish discoloration (cyanosis) of the tongue and lips.

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