Although some disagreement exists on the exact boundary between the upper and lower respiratory tracts, the upper respiratory tract is generally considered to be the airway above the glottis or vocal cords. This includes the nose, sinuses, pharynx, and larynx.

Typical infections of the upper respiratory tract include tonsillitis, pharyngitis, laryngitis, sinusitis, otitis media, certain types of influenza, and the common cold. Symptoms of URIs can include cough, sore throat, runny nose, nasal congestion, headache, low grade fever, facial pressure and sneezing.

The lower respiratory tract consists of the trachea (wind pipe), bronchial tubes, the bronchioles, and the lungs.

Lower respiratory tract infections are generally more serious than upper respiratory infections. LRIs are the leading cause of death among all infectious diseases. The two most common LRIs are bronchitis and pneumonia. Influenza affects both the upper and lower respiratory tracts, but more dangerous strains such as the highly pernicious H5N1 tend to bind to receptors deep in the lungs.

A common symptom of laryngeal papillomatosis is a perceptual change in voice quality. More specifically, hoarseness is observed. As a consequence of the narrowing of the laryngeal or tracheal parts of the airway, shortness of breath, chronic cough and stridor (i.e. noisy breathing which can sound like a whistle or a snore), can be present. As the disease progresses, occurrence of secondary symptoms such as dysphagia, pneumonia, acute respiratory distress syndrome, failure to thrive, and recurrent upper respiratory infections can be diagnosed. In children, symptoms are usually more severe and often mistaken for manifestations of other diseases such as asthma, croup or bronchitis. Therefore, diagnosis is usually delayed.

A URI may be classified by the area inflamed.

Rhinitis affects the nasal mucosa, while rhinosinusitis or sinusitis affects the nose and paranasal sinuses, including frontal, ethmoid, maxillary, and sphenoid sinuses. Nasopharyngitis (rhinopharyngitis or the common cold) affects the nares, pharynx, hypopharynx, uvula, and tonsils generally. Without involving the nose, pharyngitis inflames the pharynx, hypopharynx, uvula, and tonsils. Similarly, epiglottitis (supraglottitis) inflames the superior portion of the larynx and supraglottic area; laryngitis is in the larynx; laryngotracheitis is in the larynx, trachea, and subglottic area; and tracheitis is in the trachea and subglottic area.

In uncomplicated colds, cough and nasal discharge may persist for 14 days or more even after other symptoms have resolved.

Acute upper respiratory tract infections include rhinitis, pharyngitis/tonsillitis and laryngitis often referred to as a common cold, and their complications: sinusitis, ear infection and sometimes bronchitis (though bronchi are generally classified as part of the lower respiratory tract.) Symptoms of URTIs commonly include cough, sore throat, runny nose, nasal congestion, headache, low-grade fever, facial pressure and sneezing.

Symptoms of rhinovirus in children usually begin 1–3 days after exposure. The illness usually lasts 7–10 more days.

Color or consistency changes in mucous discharge to yellow, thick, or green are the natural course of viral upper respiratory tract infection and not an indication for antibiotics.

Group A beta hemolytic streptococcal pharyngitis/tonsillitis (strep throat) typically presents with a sudden onset of sore throat, pain with swallowing and fever. Strep throat does not usually cause runny nose, voice changes, or cough.

Pain and pressure of the ear caused by a middle ear infection (otitis media) and the reddening of the eye caused by viral conjunctivitis are often associated with upper respiratory infections.

In a typical case, an infant under two years of age develops cough, wheeze, and shortness of breath over one or two days. Crackles or wheeze are typical findings on listening to the chest with a stethoscope. The infant may be breathless for several days. After the acute illness, it is common for the airways to remain sensitive for several weeks, leading to recurrent cough and wheeze.

Some signs of severe disease include:

- poor feeding (less than half of usual fluid intake in preceding 24 hours)

- significantly decreased activity

- history of stopping breathing

- respiratory rate >70/min

- presence of nasal flaring and/or grunting

- severe chest wall recession (Hoover's sign)

- bluish skin

Laryngeal papillomatosis, also known as recurrent respiratory papillomatosis, is a rare medical condition that leads to audible changes in voice quality and narrowing of the airway. It is caused by type 6 and 11 human papillomavirus (HPV) infections of the throat, in which benign tumors or papillomas form on the larynx or other areas of the respiratory tract. Laryngeal papillomatosis is initially diagnosed through indirect laryngoscopy upon observation of growths on the larynx and can be confirmed through a biopsy. Treatment for laryngeal papillomatosis aims to remove the papillomas and limit their recurrence. Due to the recurrent nature of the virus, repeated treatments usually are needed. Laryngeal papillomatosis is primarily treated surgically, though supplemental nonsurgical and/or medical treatments may be considered in some cases. The evolution of laryngeal papillomatosis is highly variable. Though total recovery may be observed, it is often persistent despite treatment. The number of new cases of laryngeal papillomatosis cases is at approximately 4.3 cases per 100 000 children and 1.8 cases per 100 000 adults annually.

Bronchomalacia can best be described as a birth defect of the bronchus in the respiratory tract. Congenital malacia of the large airways is one of the few causes of irreversible airways obstruction in children, with symptoms varying from recurrent wheeze and recurrent lower airways infections to severe dyspnea and respiratory insufficiency. It may also be acquired later in life due to chronic or recurring inflammation resulting from infection or other airway disease.

Pulmonary aspiration is the entry of material (such as pharyngeal secretions, food or drink, or stomach contents) from the oropharynx or gastrointestinal tract into the larynx (voice box) and lower respiratory tract (the portions of the respiratory system from the trachea—i.e., windpipe—to the lungs). A person may either inhale the material, or it may be delivered into the tracheobronchial tree during positive pressure ventilation. When pulmonary aspiration occurs during eating and drinking, the aspirated material is often colloquially referred to as "going down the wrong pipe."

Consequences of pulmonary aspiration range from no injury at all, to chemical pneumonitis or pneumonia, to death within minutes from asphyxiation. These consequences depend in part on the volume, chemical composition, particle size, presence or absence of infectious agents, and underlying health status of the person. In healthy people, aspiration of small quantities of material is common and rarely results in disease or injury. People with significant underlying disease or injury, especially hospitalized patients, are at greater risk for developing respiratory complications following pulmonary aspiration because of certain factors such as depressed level of consciousness and impaired airway defenses (gag reflex and/or respiratory tract antimicrobial defense system). As the lumen of the right main bronchus is more vertical and of slightly wider diameter than that of the left, aspirated material is more likely to end up in this bronchus or one of its subsequent .

About 3.6 million cases of pulmonary aspiration or foreign body in the airway occurred in 2013.

Tracheitis is an inflammation of the trachea.

Although the trachea is usually considered part of the lower respiratory tract, in ICD-10 tracheitis is classified under "acute upper respiratory infections".

Bronchiolitis is blockage of the small airway in the lungs due to a viral infection. It usually only occurs in children less than two years of age. Symptoms may include fever, cough, runny nose, wheezing, and breathing problems. More severe cases may be associated with nasal flaring, grunting, or the skin between the ribs pulling in with breathing. If the child has not been able to feed properly, signs of dehydration may be present.

Bronchiolitis is usually the result of infection by respiratory syncytial virus (72% of cases) or human rhinovirus (26% of cases). Diagnosis is generally based on symptoms. Tests such as a chest X-ray or viral testing are not routinely needed. Urine testing may be considered in those with a fever.

There is no specific treatment. Supportive care at home is generally sufficient. Occasionally hospital admission for oxygen, support with feeding, or intravenous fluids is required. Evidence for antibiotics, antivirals, bronchodilators, or nebulized hypertonic saline or epinephrine is either unclear or not supportive.

About 10% to 30% of children under the age of two years are affected by bronchiolitis at some point in time. It more commonly occurs in the winter in the Northern hemisphere. The risk of death among those who are admitted to hospital is about 1%. Outbreaks of the condition were first described in the 1940s.

Bronchomalacia is a term for weak cartilage in the walls of the bronchial tubes, often occurring in children under six months. Bronchomalacia means 'floppiness' of some part of the bronchi. Patients present with noisy breathing and/or wheezing. There is collapse of a main stem bronchus on exhalation. If the trachea is also involved the term tracheobronchomalacia (TBM) is used. If only the upper airway the trachea is involved it is called tracheomalacia (TM). There are two types of bronchomalacia. Primary bronchomalacia is due to a deficiency in the cartilaginous rings. Secondary bronchomalacia may occur by extrinsic compression from an enlarged vessel, a vascular ring or a bronchogenic cyst. Though uncommon, idiopathic (of unknown cause) tracheobronchomalacia has been described in older adults.

Bacterial tracheitis is a bacterial infection of the trachea and is capable of producing airway obstruction.

One of the most common causes is "Staphylococcus aureus" and often follows a recent viral upper respiratory infection. Bacterial tracheitis is a rare complication of influenza infection. It is the most serious in young children, possibly because of the relatively small size of the trachea that gets easily blocked by swelling. The most frequent sign is the rapid development of stridor. It is occasionally confused with croup.

If it is inflamed, a condition known as tracheitis can occur. In this condition there can be inflammation of the linings of the trachea. A condition called tracheo-bronchitis can be caused, when the mucous membrane of the trachea and bronchi swell. A collapsed trachea is formed as a result of defect in the cartilage, that makes the cartilage unable to support the trachea and results in dry hacking cough. In this condition there can be inflammation of the linings of the trachea. If the connective nerve tissues in the trachea degenerate it causes tracheomalacia. Infections to the trachea can cause tracheomegaly.

Lower respiratory tract infection (LRTI), while often used as a synonym for pneumonia, can also be applied to other types of infection including lung abscess and acute bronchitis. Symptoms include shortness of breath, weakness, fever, coughing and fatigue.

There are a number of symptoms that are characteristic of lower respiratory tract infections. The two most common are bronchitis and edema. Influenza affects both the upper and lower respiratory tracts.

Antibiotics are the first line treatment for pneumonia; however, they are not effective or indicated for parasitic or viral infections. Acute bronchitis typically resolves on its own with time.

In 2015 there were about 291 million cases. These resulted in 2.74 million deaths down from 3.4 million deaths in 1990. This was 4.8% of all deaths in 2013.

Bronchitis describes the swelling or inflammation of the bronchial tubes. Additionally, bronchitis is described as either acute or chronic depending on its presentation and is also further described by the causative agent. Acute bronchitis can be defined as acute bacterial or viral infection of the larger airways in healthy patients with no history of recurrent disease. It affects over 40 adults per 1000 each year and consists of transient inflammation of the major bronchi and trachea. Most often it is caused by viral infection and hence antibiotic therapy is not indicated in immunocompetent individuals. Viral bronchitis can sometimes be treated using antiviral medications depending on the virus causing the infection, and medications such as anti-inflammatory drugs and expectorants can help mitigate the symptoms. Treatment of acute bronchitis with antibiotics is common but controversial as their use has only moderate benefit weighted against potential side effects (nausea and vomiting), increased resistance, and cost of treatment in a self-limiting condition. Beta2 agonists are sometimes used to relieve the cough associated with acute bronchitis. In a recent systematic review it was found there was no evidence to support their use.

Woodring et al. (1991) suggested the following diagnostic criteria for tracheomegaly in adults based on chest radiography:

- Adult Males: Tracheal transverse diameter > 25 mm and sagittal diameter > 27 mm.

- Adult Females: Tracheal transverse diameter > 21 mm and sagittal diameter > 23 mm.

Extraesophageal symptoms result from exposure of the upper aerodigestive tract to gastric contents. This causes a variety of symptoms, including hoarseness, postnasal drip, sore throat, difficulty swallowing, indigestion, chronic cough, wheezing, globus pharyngeus, and chronic throat-clearing. Some people with LPR have heartburn, while others have little to no heartburn as refluxed stomach contents do not remain in the esophagus long enough to irritate the surrounding tissue. Individuals with more severe forms of LPR may experience abrasion of tooth enamel due to intermittent presence of gastric contents in the oral cavity.

Additionally, LPR can cause inflammation in the vocal tract which results in the symptom of dysphonia or hoarseness. Hoarseness is considered to be one of the primary symptoms of LPR and is associated with complaints such as strain, vocal fatigue, muskuloskeletal tension, and hard glottal attacks, all of which can reduce a person's ability to communicate effectively. Moreover, LPR patients may try to compensate for their hoarseness by increasing muscular tension in their vocal tract. This hyper-functional technique adopted in response to the inflammation caused by LPR can lead to a condition called muscle tension dysphonia and may persist even after the hoarseness and inflammation has disappeared. A speech-language pathologist will often need to be involved to help resolve this maladaptive, compensatory pattern through the implementation of voice therapy.

LPR presents as a chronic and intermittent disease in children. LPR in children and infants tends to manifest with a unique set of symptoms. Symptoms seen in children with LPR include a cough, hoarseness, stridor, sore throat, asthma, vomiting, globus sensation, wheezing, aspiration and recurrent pneumonia. Common symptoms of LPR in infants include wheezing, stridor, persistent or recurrent cough, apnea, feeding difficulties, aspiration, regurgitation, and failure to thrive. Moreover, LPR in children is commonly concomitant with laryngeal disorders such as laryngomalacia, subglottic stenosis, and laryngeal papillomatosis.

Pneumonia occurs in a variety of situations and treatment must vary according to the situation. It is classified as either community or hospital acquired depending on where the patient contracted the infection. It is life-threatening in the elderly or those who are immunocompromised. The most common treatment is antibiotics and these vary in their adverse effects and their effectiveness. Pneumonia is also the leading cause of death in children less than five years of age in low income countries. The most common cause of pneumonia is pneumococcal bacteria, "Streptococcus pneumoniae" accounts for 2/3 of bacteremic pneumonias. This is a dangerous type of lung infection with a mortality rate of around 25%.

For optimal management of a pneumonia patient, the following must be assessed: pneumonia severity (including treatment location, e.g., home, hospital or intensive care), identification of causative organism, analgesia of chest pain, the need for supplemental oxygen, physiotherapy, hydration, bronchodilators and possible complications of emphysema or lung abscess.

Pulmonary aspiration is often followed by bacterial pneumonia. Community-acquired aspiration pneumonia is usually caused by anaerobic bacteria, whereas hospital-acquired aspiration pneumonia is more often caused by mixed flora, including both aerobic and anaerobic bacteria.

Hemoptysis is the coughing up of blood or blood-stained mucus from the bronchi, larynx, trachea, or lungs. This can occur with lung cancer, infections such as tuberculosis, bronchitis, or pneumonia, and certain cardiovascular conditions. Hemoptysis is considered massive at . In such cases, there are always severe injuries. The primary danger comes from choking, rather than blood loss.

Respiratory disease is a medical term that encompasses pathological conditions affecting the organs and tissues that make gas exchange possible in higher organisms, and includes conditions of the upper respiratory tract, trachea, bronchi, bronchioles, alveoli, pleura and pleural cavity, and the nerves and muscles of breathing. Respiratory diseases range from mild and self-limiting, such as the common cold, to life-threatening entities like bacterial pneumonia, pulmonary embolism, acute asthma and lung cancer.

The study of respiratory disease is known as pulmonology. A doctor who specializes in respiratory disease is known as a pulmonologist, a chest medicine specialist, a respiratory medicine specialist, a respirologist or a thoracic medicine specialist.

Respiratory diseases can be classified in many different ways, including by the organ or tissue involved, by the type and pattern of associated signs and symptoms, or by the cause of the disease.

Conditions which commonly involve hemoptysis include bronchitis and pneumonia, lung cancers and tuberculosis. Other possible underlying causes include aspergilloma, bronchiectasis, coccidioidomycosis, pulmonary embolism, pneumonic plague, and cystic fibrosis. Rarer causes include hereditary hemorrhagic telangiectasia (HHT or Rendu-Osler-Weber syndrome), Goodpasture's syndrome, and granulomatosis with polyangiitis. In children, hemoptysis is commonly caused by the presence of a foreign body in the airway. The condition can also result from over-anticoagulation from treatment by drugs such as warfarin.

Blood-laced mucus from the sinus or nose area can sometimes be misidentified as symptomatic of hemoptysis (such secretions can be a sign of nasal or sinus cancer, but also a sinus infection). Extensive non-respiratory injury can also cause one to cough up blood. Cardiac causes like congestive heart failure and mitral stenosis should be ruled out.

The origin of blood can be identified by observing its color. Bright-red, foamy blood comes from the respiratory tract, whereas dark-red, coffee-colored blood comes from the gastrointestinal tract. Sometimes hemoptysis may be rust-colored.

The most common cause of minor hemoptysis is bronchitis.

- Lung cancer, including both non-small cell lung carcinoma and small cell lung carcinoma.

- Sarcoidosis

- Aspergilloma

- Tuberculosis

- Histoplasmosis

- Pneumonia

- Pulmonary edema

- Pulmonary embolism

- Foreign body aspiration and aspiration pneumonia

- Goodpasture's syndrome

- Granulomatosis with polyangiitis

- Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)

- Bronchitis

- Bronchiectasis

- Pulmonary embolism

- Anticoagulant use

- Trauma

- Lung abscess

- Mitral stenosis

- Tropical eosinophilia

- Bleeding disorders

- Hughes-Stovin Syndrome and other variants of Behçet's disease

- Squamous Cell Carcinoma Of Esophagus

Tracheobronchomegaly is a very rare congenital disorder of the lung primarily characterized by an abnormal widening of the upper airways. The abnormally widened trachea and mainstem bronchi are associated with recurrent lower respiratory tract infection and copious purulent sputum production, eventually leading to bronchiectasis and other respiratory complications.

Chronic respiratory diseases (CRDs) are diseases of the airways and other structures of the lung. This disease could be characterized by a high inflammatory cells recruitment (neutrophil) and/or destructive cycle of infection, (e.g. mediated by "Pseudomonas aeruginosa"). Some of the most common are asthma, chronic obstructive pulmonary disease, or acute respiratory distress syndrome . CRDs are not curable, however, various forms of treatment that help dilate major air passages and improve shortness of breath can help control symptoms and increase the quality of life for people with the disease.

it usually lasts for three months to two years

LPR is often regarded as a subtype of GERD that occurs when stomach contents flow upward through the esophagus and reach the level of the larynx and pharynx. However, LPR is associated with a distinct presentation of symptoms. LPR and GERD frequently differ in the relative prevalence of heartburn and throat clearing. While heartburn is present in over 80% of GERD cases, it occurs in only 20% of LPR cases. Throat clearing shows the opposite prevalence pattern, occurring in approximately 87% of LPR cases and in fewer than 5% of GERD cases. Unlike GERD, LPR also poses a risk for bronchitis or pneumonitis as reflux of stomach acid to the level of the larynx can result in aspiration. LPR is also commonly associated with erythema, or redness, as well as edema in the tissues of the larynx that are exposed to gastric contents. In contrast, most cases of GERD are nonerosive, with no apparent injury to the mucosal lining of the esophageal tissue exposed to the refluxed material.

Differences in the molecular structure of the epithelial tissue lining the laryngopharyngeal region may be partly responsible for the different symptomatic manifestations of LPR in comparison to GERD. In contrast to the resistant stratified squamous epithelium lining the esophagus, the larynx is lined by ciliated respiratory epithelium, which is more fragile and susceptible to damage. While the epithelium lining the esophagus is capable of withstanding as many as 50 instances of exposure to gastric contents each day, which is the uppermost estimate considered to be within the range of normal physiologic functioning, injury to laryngeal epithelium can occur following exposure to only small amounts of acidic gastric contents.

Squamous cell papilloma of the mouth or throat is generally diagnosed in people between the ages of 30 and 50, and is normally found on the inside of the cheek, on the tongue, or inside of lips. Oral papillomas are usually painless, and not treated unless they interfere with eating or are causing pain. They do not generally mutate to cancerous growths, nor do they normally grow or spread. Oral papillomas are most usually a result of the infection with types HPV-6 and HPV-11.