Nasal obstruction characterized by insufficient airflow through the nose can be a subjective sensation or the result of objective pathology. It is difficult to quantify by subjective complaints or clinical examinations alone, hence both clinicians and researchers depend both on concurrent subjective assessment and on objective measurement of the nasal airway. Often a doctor's assessment of a perfectly patent nasal airway might differ with a patient's complaint of an obstructed nose.

Nasal congestion is the blockage of the nasal passages usually due to membranes lining the nose becoming swollen from inflamed blood vessels.

Nasal decongestants target the discomfort directly. These come as nasal sprays, inhalers, and as oral pills.

Nasal congestion has many causes and can range from a mild annoyance to a life-threatening condition. Most people prefer to breathe through the nose (historically referred to as "obligate nasal breathers"). Nasal congestion in an infant in the first few months of life can interfere with breastfeeding and cause life-threatening respiratory distress; in older children and adolescents it is often just an annoyance but can cause other difficulties.

Nasal congestion can interfere with the hearing and speech. Significant congestion may interfere with sleep, cause snoring, and can be associated with sleep apnea. In children, nasal congestion from enlarged adenoids has caused chronic sleep apnea with insufficient oxygen levels and hypoxia, as well as right-sided heart failure. The problem usually resolves after surgery to remove the adenoids and tonsils, however the problem often relapses later in life due to craniofacial alterations from chronic nasal congestion.

Nasal congestion can also cause mild facial and head pain, and a degree of discomfort, often from allergies or the common cold.

Rhinorrhea is characterized by an excess amount of mucus produced by the mucous membranes that line the nasal cavities. The membranes create mucus faster than it can be processed, causing a backup of mucus in the nasal cavities. As the cavity fills up, it blocks off the air passageway, causing difficulty breathing through the nose. Air caught in nasal cavities, namely the sinus cavities, cannot be released and the resulting pressure may cause a headache or facial pain. If the sinus passage remains blocked, there is a chance that sinusitis may result. If the mucus backs up through the Eustachian tube, it may result in ear pain or an ear infection. Excess mucus accumulating in the throat or back of the nose may cause a post-nasal drip, resulting in a sore throat or coughing. Additional symptoms include sneezing, nosebleeds, and nasal discharge.

Rhinorrhea can occur as a symptom of opioid withdrawal accompanied by lacrimation. Other causes include cystic fibrosis, whooping cough, nasal tumors, hormonal changes, and cluster headaches. Due to changes in clinical practice, Rhinorrhea is now reported as a frequent side effect of oxygen-intubation during colonoscopy procedures [A simple, innovative way to reduce rhinitis symptoms after sedation during endoscopy" by Nai-Liang Li, et al, Canadian Journal of Gastroenterology, 2011, Feb; volume 25(2): pages 68–72.]. Rhinorrhea can also be the side effect of several genetic disorders, such as primary ciliary dyskinesia.

The characteristic presentation of RM involves nasal congestion without rhinorrhea, postnasal drip, or sneezing following several days of decongestant use. This condition typically occurs after 5–7 days of use of topical decongestants. Patients often try increasing both the dose and the frequency of nasal sprays upon the onset of RM, worsening the condition. The swelling of the nasal passages caused by rebound congestion may eventually result in permanent turbinate hyperplasia, which may block nasal breathing until surgically removed.

Paroxysmal sneezing in morning, especially in morning while getting out of the bed. Excessive rhinorrhea - watering discharge from the nose when patient bends forward. Nasal obstruction - bilateral nasal stuffiness alternates from one site to other; this is more marked at night, when the dependent side of nose is often blocked. Postnasal drip.

Nonallergic rhinitis cases may subsequently develop polyps, turbinate hypertrophy and sinusitis.

Rhinitis medicamentosa (or RM) is a condition of rebound nasal congestion brought on by extended use of topical decongestants (e.g., oxymetazoline, phenylephrine, xylometazoline, and naphazoline nasal sprays) and certain oral medications (e.g., sympathomimetic amines and various 2-imidazolines) that constrict blood vessels in the lining of the nose.

PND is suggested to be a cause of extra-oral halitosis, especially when a sinus infection is also present. Acid reflux or heartburn is believed to aggravate and in some cases cause post-nasal drip. Post-nasal drip can be a cause of laryngeal inflammation and hyperresponsiveness, leading to symptoms of vocal cord dysfunction (VCD).

Post-nasal drip (PND, also termed upper airway cough syndrome, UACS, or post nasal drip syndrome, PNDS) occurs when excessive mucus is produced by the nasal mucosa. The excess mucus accumulates in the throat or back of the nose. It is caused by rhinitis, sinusitis, gastroesophageal reflux disease (GERD), or by a disorder of swallowing (such as an esophageal motility disorder). It is frequently caused by an allergy, which may be seasonal or persistent throughout the year.

However, other researchers argue that mucus dripping down the back of the throat from the nasal cavity is a normal physiologic process that occurs in healthy individuals. Post-nasal drip has been challenged as a syndrome due to a lack of an accepted definition, pathologic tissue changes, and available biochemical tests.

Headache/facial pain or pressure of a dull, constant, or aching sort over the affected sinuses is common with both acute and chronic stages of sinusitis. This pain is typically localized to the involved sinus and may worsen when the affected person bends over or when lying down. Pain often starts on one side of the head and progresses to both sides.

Acute sinusitis may be accompanied by thick nasal discharge that is usually green in color and may contain pus (purulent) and/or blood. Often a localized headache or toothache is present, and it is these symptoms that distinguish a sinus-related headache from other types of headaches, such as tension and migraine headaches. Another way to distinguish between toothache and sinusitis is that the pain in sinusitis is usually worsened by tilting the head forwards and with valsalva maneuvers.

Infection of the eye socket is possible, which may result in the loss of sight and is accompanied by fever and severe illness. Another possible complication is the infection of the bones (osteomyelitis) of the forehead and other facial bones – Pott's puffy tumor.

Sinus infections can also cause middle ear problems due to the congestion of the nasal passages. This can be demonstrated by dizziness, "a pressurized or heavy head", or vibrating sensations in the head. Post-nasal drip is also a symptom of chronic rhinosinusitis.

Halitosis (bad breath) is often stated to be a symptom of chronic rhinosinusitis; however, gold standard breath analysis techniques have not been applied. Theoretically, there are several possible mechanisms of both objective and subjective halitosis that may be involved.

A 2004 study suggested that up to 90% of "sinus headaches" are actually migraines. The confusion occurs in part because migraine involves activation of the trigeminal nerves, which innervate both the sinus region and the meninges surrounding the brain. As a result, it is difficult to accurately determine the site from which the pain originates. People with migraines do not typically have the thick nasal discharge that is a common symptom of a sinus infection.

Sinusitis (or rhinosinusitis) is defined as an inflammation of the mucous membrane that lines the paranasal sinuses and is classified chronologically into several categories:

- Acute rhinosinusitis – A new infection that may last up to four weeks and can be subdivided symptomatically into severe and non-severe. Some use definitions up to 12 weeks.

- Recurrent acute rhinosinusitis – Four or more full episodes of acute sinusitis that occur within one year

- Subacute rhinosinusitis – An infection that lasts between four and 12 weeks, and represents a transition between acute and chronic infection

- Chronic rhinosinusitis – When the signs and symptoms last for more than 12 weeks.

- Acute exacerbation of chronic rhinosinusitis – When the signs and symptoms of chronic rhinosinusitis exacerbate, but return to baseline after treatment

All these types of sinusitis have similar symptoms, and are thus often difficult to distinguish. Acute sinusitis is very common. Roughly ninety percent of adults have had sinusitis at some point in their life.

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.

Permanent loss of smell and impairment of taste may also be a result of this disease, even after the symptoms are cured.

Extreme deviation of nasal septum may be accompanied by atrophic rhinitis on the wider side.

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.

With patulous Eustachian tube, variations in upper airway pressure associated with respiration are transmitted to the middle ear through the Eustachian tube. This causes an unpleasant fullness feeling in the middle ear and alters the auditory perception. Complaints seem to include muffled hearing and autophony. In addition, patulous Eustachian tube generally feels dry with no clogged feeling or sinus pressure.

Some patients with this condition are disturbed by the perceived volume of their voice, causing them to speak very quietly. Their own voice may also sound lower to other people, because the trachea has more volume when the Eustachian tube is open. The patient may also sound as if they have congestion when speaking. Some sufferers may have difficulty in normal activities. They may also experience increased breathing rate, such as that brought on by physical activity. The increased activity not only increases the rate and force of pressure changes in the airway, which is therefore transmitted more forcefully into the middle ear, but also drives increased blood flow to peripheral muscles, compounding the problem by further depleting the Eustachian tube of extracellular fluid and increasing patency. The combination can lead to severe exacerbation of the symptoms. The urge to clear the ear is often mentioned.

Acute adenoiditis is characterized by fever, runny nose, nasal airway obstruction resulting in predominantly oral breathing, snoring and sleep apnea, Rhinorrhea with serous secretion in viral forms and mucous-purulent secretion in bacterial forms. In cases due to viral infection symptoms usually recede spontaneously after 48 hours, symptoms of bacterial adenoiditis typically persist up to a week. Adenoiditis is sometimes accompanied by tonsillitis. Repeated adenoiditis may lead to enlarged adenoids.

Rhinoliths present as unilateral nasal obstruction. Foul-smelling, blood-stained discharge is often present. Epistaxis and pain may occur due to the ulceration of surrounding mucosa.

Adenoiditis is the inflammation of the adenoid tissue, usually caused by an infection. Adenoiditis is treated using medication (antibiotics and/or steroids) or surgical intervention.

Adenoiditis may produce cold-like symptoms. However, adenoiditis symptoms often persist for ten or more days, and often include pus-like discharge from nose.

The infection cause is usually viral. However, if the adenoiditis is caused by a bacterial infection, antibiotics may be prescribed for treatment. A steroidal nasal spray may also be prescribed in order to reduce nasal congestion. Severe or recurring adenoiditis may require surgical removal of the adenoids (adenotonsillectomy).

Chronic rhinitis is a form of atrophy of the mucous membrane and glands of the nose.

Autophonia (self-hearing from inside, strongly amplified) seems to be a common symptom to all PET patients. Unfortunately, its presence also reveals an advanced degree of patency, requiring in most cases surgical management. Other symptoms of PET, such as tinnitus, fullness and ear blockage, can also be reported by patients suffering from obstructive ET dysfunction. This differential diagnosis problem unfortunately leads to some surgeries proposed by well-intentioned but inexperienced ENT surgeons. Some of these surgeries may make things worse.

At the beginning, patients hear their own voice "from inside". They describe it as being amplified and unpleasant. Patients frequently avoid speaking and retire in a rising solitude. Lying head down may help since it increases venous blood pressure and congestion of the mucosa.

With time patients may develop respiratory autophonia. At this stage, they hear "from inside”. They describe hearing their own respiration and sometimes other bodily functions, like heartbeat. Some patients may find this unbearable and depression is common. Psychological supervision may be indicated.

Rhinitis is categorized into three types (although infectious rhinitis is typically regarded as a separate clinical entity due to its transient nature): (i) infectious rhinitis includes acute and chronic bacterial infections; (ii) nonallergic (vasomotor) rhinitis includes idiopathic, hormonal, atrophic, occupational, and gustatory rhinitis, as well as rhinitis medicamentosa (drug-induced); (iii) allergic rhinitis, triggered by pollen, mold, animal dander, dust, Balsam of Peru, and other inhaled allergens.

A rhinolith is a calculus present in the nasal cavity. The word is derived from the roots "" and "", literally meaning "nose stone". It is an uncommon medical phenomenon, not to be confused with dried nasal mucus. A rhinolith usually forms around the nucleus of a small exogenous foreign body, blood clot or secretion by slow deposition of calcium and magnesium salts. Over a period of time, they grow into large irregular masses that fill the nasal cavity. They may cause pressure necrosis of the nasal septum or lateral wall of nose. Rhinoliths can cause nasal obstruction, epistaxis, headache, sinusitis and epiphora. They can be diagnosed from the history with unilateral foul smelling blood stained nasal discharge or by anterior rhinoscopy. On probing probe can be passed around all its corners. In both CT and MRI rhinolith will appear like a radiopaque irregular material. Small rhinoliths can be removed by foreign body hook. Whereas large rhinoliths can be removed either by crushing with luc's forceps or by Moore's lateral rhinotomy approach.

Individuals with the condition of fungal sinusitis mostly present with features that include facial pain and pain around the eyes, nasal congestion, rhinorrhea(running nose), headache, later there may be ophthalmoplegia (paralysis of ocular muscles).