OVERVIEW

What is the upper respiratory tract?

The respiratory tract includes the nose, pharynx, larynx, trachea, and bronchi. The nose, pharynx, and larynx are commonly referred to as the upper respiratory tract, while the trachea and bronchi are called the lower respiratory tract.

What is acute upper respiratory tract infection?

Acute upper respiratory tract infection, abbreviated as "URI," refers to acute inflammation of the nasal cavity, pharynx, and larynx caused by pathogenic microorganisms such as viruses or bacteria. Common symptoms include sneezing, runny nose, cough, sore throat, fever, etc.^[1,2]. Most URIs are caused by viral infections, with a minority caused by bacteria^[3].

Generally, symptoms are mild and do not require treatment, as the body's immune system can resolve the infection on its own. If symptoms are more pronounced, symptomatic medications may be taken.

Is acute upper respiratory tract infection common?

Very common. URI is one of the most prevalent infectious diseases in humans. Adults experience an average of 2–3 infections per year, while children average 4–8 infections annually. It often occurs during seasonal transitions, winter, and spring, and may also spread during sudden climate changes^[3].

Is acute upper respiratory tract infection the same as the common cold?

URI is not a single disease but a group of conditions, typically including the common cold, acute pharyngitis, acute laryngitis, acute tonsillitis, etc.^[3]. The common cold can be caused by various viruses, most commonly rhinoviruses. It primarily manifests as nasal symptoms such as sneezing, nasal congestion, and clear nasal discharge.

SYMPTOMS

What are the symptoms of acute upper respiratory tract infection?

The symptoms of acute upper respiratory tract infection are related to the pathogen and type of infection.

• Common cold: Also known as upper respiratory catarrh or acute rhinitis, commonly referred to as a "cold." Main symptoms include nasal issues such as sneezing, nasal congestion, and clear nasal discharge, as well as coughing, dry throat, or throat irritation. Some may experience mild fever, slight chills, or headache. Severe cases may also involve headache, fever, or chills^[3].
• Acute viral pharyngitis: Caused by viruses such as rhinovirus or enterovirus. Main symptoms include throat irritation and a burning sensation, with rare coughing^[3].
• Acute viral laryngitis: Caused by adenovirus, influenza virus, etc. Symptoms include difficulty speaking, hoarseness, and may be accompanied by coughing, sore throat, or fever^[3].
• Acute herpetic pharyngitis: Caused by Coxsackievirus A, more common in summer and among children. Main symptoms include severe sore throat and fever^[3].
• Acute pharyngoconjunctival fever: Mainly caused by Coxsackievirus or adenovirus, often occurring in summer and more common in children. Symptoms include tearing, fever, photophobia, sore throat, and visible congestion in the throat and conjunctiva^[3].
• Acute tonsillopharyngitis: Usually caused by bacterial infections such as Streptococcus pyogenes or Streptococcus pneumoniae. Symptoms include sudden onset, fatigue, severe sore throat, high fever (above 39°C), and chills^[3].

Can acute upper respiratory tract infection cause diarrhea?

Although symptoms of upper respiratory infections are mainly concentrated in the nose and throat, due to individual differences and pathogen characteristics, a small number of patients may experience abdominal pain, bloating, nausea, or vomiting.

If these symptoms occur, seek medical attention promptly to determine whether it is a common cold, a more severe gastrointestinal cold, or a digestive system disorder.

Can acute upper respiratory tract infection cause dizziness or vertigo?

It is possible. Dizziness or vertigo may occur due to the following reasons:

• Severe nasal congestion or discharge during infection, leading to insufficient blood and oxygen supply to the brain, causing dizziness.
• The virus causing the infection may also trigger vestibular neuronitis, which affects balance and can lead to vertigo.
• Secondary infections such as sinusitis or otitis media^[3] may worsen dizziness or vertigo.

Note: Conditions like cervical spondylosis, Ménière's disease, hypertension, or hyperlipidemia can also cause dizziness or vertigo. Upper respiratory infections may trigger or worsen these symptoms. If dizziness or vertigo persists regardless of infection, further medical examination is recommended.

What complications can acute upper respiratory tract infection cause?

Upper respiratory infections are usually mild and self-limiting, rarely leading to complications or death.

In rare cases, complications such as acute sinusitis, otitis media, tracheobronchitis, or even pneumonia may occur. Some acute pharyngitis patients may develop secondary Streptococcus pyogenes infections, leading to rheumatic fever or glomerulonephritis. Very few may experience viral myocarditis, which can be life-threatening.

Why does coughing persist for a long time after recovering from acute upper respiratory tract infection?

This is mostly due to post-infectious cough.

Coughing is a primary symptom of upper respiratory infections. However, some patients continue to experience recurrent paroxysmal coughing even after other symptoms improve or disappear. Without timely treatment, this may lead to chronic cough. Clinical data show that post-infectious cough is a major cause of chronic cough, with increasing incidence in recent years^[4].

Can acute upper respiratory tract infection cause olfactory dysfunction?

It is possible.

Most people experience temporary olfactory dysfunction due to nasal congestion during infection, which usually resolves once congestion improves. However, a small number of patients may find their sense of smell does not return after nasal symptoms subside, mainly due to viral damage to olfactory nerves. In such cases, prompt consultation with an otolaryngologist is advised.

CAUSES

What are the causes of acute upper respiratory tract infections?

The cause of acute upper respiratory tract infections is the infection by pathogenic microorganisms such as viruses and bacteria.

The most common is the rhinovirus, which causes about half of colds.

There are over 200 other viruses that can cause colds, including influenza virus, respiratory syncytial virus, parainfluenza virus, coronavirus, adenovirus, and enterovirus, among others^[3].

What factors easily trigger acute upper respiratory tract infections?

Common triggers include seasonal changes, sudden temperature drops, getting caught in the rain, stress (such as major exams, job interviews, bereavement), excessive fatigue, and lack of sleep^[3].

Who is more susceptible to acute upper respiratory tract infections?

• People with weaker immune systems: young children, the elderly, and those who are malnourished;
• Smokers;
• Individuals with diseases that weaken the immune system, such as cancer, diabetes, chronic liver or kidney disease, or long-term corticosteroid users;
• Those with chronic respiratory conditions: such as chronic tonsillitis, chronic rhinitis, chronic bronchitis, or bronchiectasis patients^[3].

Are acute upper respiratory tract infections contagious?

Yes, they are contagious. Upper respiratory infections are among the most common infectious diseases^[3]. They can cause small outbreaks during sudden weather changes.

The pathogens causing these infections are mainly spread through airborne droplets (e.g., face-to-face talking, coughing, sneezing) or contact transmission (e.g., touching contaminated hands or objects).

Why can acute upper respiratory tract infections recur repeatedly?

Statistics show that adults experience upper respiratory infections 2–4 times a year, while children have them more frequently, 4–8 times a year^[3]. This is because the pathogens responsible are mainly various viruses. The body only develops temporary immunity to the specific virus causing the current infection. Once immunity wanes or a different virus is encountered, reinfection can occur, leading to repeated episodes.

Do acute upper respiratory tract infections only occur in winter and spring?

No, they can occur year-round but are more common in winter and spring^[3].

DIAGNOSIS

What tests are needed for acute upper respiratory tract infection?

Most acute upper respiratory tract infections are caused by viruses and generally do not require special tests. Doctors can make a diagnosis by inquiring about symptoms and performing a physical examination.

A physical examination includes measuring body temperature, observing the eyes, nose, and throat, and auscultating the heart and lungs, among other procedures. Patients may exhibit symptoms such as low-grade fever, conjunctival congestion, nasal mucosal swelling, and throat redness, but there should be no abnormal findings like heart murmurs (referring to abnormal sounds produced by the heart during its work, apart from normal heart sounds and extra sounds) or lung crackles^[5].

If the doctor suspects a condition other than an upper respiratory infection after questioning and examination, they may recommend tests such as blood tests or pathogen tests (using nasal or throat swabs to identify the specific virus)^[3].

What is the difference between acute upper respiratory tract infection and influenza?

Influenza is a respiratory infection caused by the influenza virus, often with sudden onset. It primarily manifests as systemic symptoms such as fever, headache, muscle pain, and fatigue, while respiratory symptoms like nasal congestion, runny nose, and cough are mild or absent^[3]. Young children, the elderly, and those with weakened immune systems are prone to severe complications. Since influenza is contagious, early medical attention is essential.

What is the difference between acute upper respiratory tract infection and allergic rhinitis?

The symptoms of the common cold (a type of upper respiratory infection) and allergic rhinitis are very similar, primarily including sneezing, clear nasal discharge, and nasal congestion.
The following aspects can help distinguish them:

• Allergic rhinitis is usually triggered by exposure to specific allergens such as pollen, dust mites, or cold air^[3].
• Allergic rhinitis often starts suddenly, with repeated bouts of sneezing and runny nose, whereas the common cold develops gradually, with symptoms worsening progressively.
• Allergic rhinitis resolves quickly after avoiding the allergen, whereas the common cold typically takes about a week to recover^[3].
• Blood tests or an otolaryngologist's examination of nasal mucosa under a nasal speculum can also help differentiate the two conditions.

TREATMENT

Which department should I visit for acute upper respiratory tract infection?

Depending on the symptoms, you can go to the respiratory medicine department, general internal medicine department, or fever clinic.

Does acute upper respiratory tract infection require treatment? How is it treated?

Most acute upper respiratory tract infections are caused by viruses, with mild symptoms and few complications. They usually resolve on their own within 1–2 weeks, so medication may not be necessary. Resting and drinking plenty of water can help the body recover^[3].

If symptoms such as fever, headache, and body aches are severe, medication can be used under a doctor's guidance. For example, antipyretic and analgesic drugs (such as acetaminophen or ibuprofen) can reduce fever and relieve pain. If nasal congestion or runny nose is severe, ephedrine-based medications can alleviate nasal symptoms. For allergic reactions, antihistamines may be used. These medications are symptomatic treatments that relieve discomfort but do not eliminate pathogens or shorten recovery time.

What are the side effects of commonly used antihistamines for acute upper respiratory tract infection?

First-generation antihistamines (e.g., chlorpheniramine maleate) can cross the blood-brain barrier and often cause side effects such as drowsiness, reduced attention, and impaired cognitive learning ability^[6]. Therefore, many cold medicines containing antihistamines specify in their instructions: "Do not drive, operate machinery, or perform high-altitude work after taking this medication." However, some nighttime cold medicines use this side effect as a sleep aid.

Second-generation antihistamines (e.g., cetirizine) improve on this issue, rarely causing drowsiness, but they may have adverse effects such as cardiac toxicity and weight gain^[6].

Newer second-generation antihistamines (e.g., desloratadine) act faster than the previous types, have no cardiac toxicity, and are safer for patients with liver or kidney dysfunction. Although they may cause dizziness, dry mouth, headache, or nausea, these symptoms disappear quickly after stopping the medication^[6].

Does acute upper respiratory tract infection require intravenous infusion?

Oral medication should be the first choice for treating upper respiratory infections, and unnecessary intravenous infusion should be avoided. Intravenous infusion is only suitable in the following cases:

• The infection worsens pre-existing conditions or causes complications requiring intravenous medication.
• Severe diarrhea or high fever leads to dehydration or electrolyte imbalance, requiring fluid and electrolyte replenishment.
• Gastrointestinal discomfort or vomiting prevents eating, necessitating intravenous fluids to maintain basic metabolism.

Are antibacterial drugs (including antibiotics) needed for acute upper respiratory tract infection?

Most upper respiratory infections are caused by viruses, and antibacterial drugs cannot kill viruses, so they should not be used indiscriminately. Without a doctor's guidance, misuse of antibacterial drugs can lead to adverse reactions and contribute to bacterial resistance.

What should be noted when treating acute upper respiratory tract infection in children?

Ibuprofen or acetaminophen is the preferred choice for reducing fever.

Dosage differs from adults, so medication should be taken under a doctor's guidance. Syrups or suspensions are preferred^[7,8].

Aspirin and other salicylate drugs should be used with caution in children with fever^[7], as they may trigger Reye's syndrome (a condition involving brain and liver damage, with symptoms such as nausea, vomiting, drowsiness, coma, delirium, seizures, and liver enlargement, which is linked to aspirin use during viral infections) and even death.

What should be noted when treating acute upper respiratory tract infection in pregnant or breastfeeding women?

Pregnant and breastfeeding women should use cold medications cautiously and consult a doctor first.

Pregnant women should avoid aspirin, diclofenac sodium, diphenhydramine, ibuprofen, and dextromethorphan, as these may affect fetal development or prolong pregnancy. Guaifenesin is contraindicated in the first trimester.

Breastfeeding women should avoid diphenhydramine and chlorpheniramine maleate, as these drugs can pass into breast milk and affect infants^[7].

What should I do if I keep coughing after an acute upper respiratory tract infection?

This is known as "post-upper respiratory infection cough" and usually resolves on its own. If the cough is severe or prolonged, short-term use of antihistamines or cough suppressants may be considered under a doctor's guidance^[4]. For a few patients with persistent cough, inhaled or oral corticosteroids may be used if general treatments are ineffective.

How is post-viral olfactory dysfunction treated?

There is currently no effective treatment for post-viral olfactory dysfunction. Under a doctor's guidance, vitamins, corticosteroids, or neurotrophic drugs may be tried, as they might offer some benefit.

DIET & LIFESTYLE

Why should you drink more water for acute upper respiratory tract infection? What should you pay attention to?

Doctors often advise patients with upper respiratory infections to drink more water, mainly to compensate for fluid loss caused by fever, dilute phlegm for easier expulsion, and promote the elimination of pathogens and metabolic waste. However, for some special groups, water intake should be approached with caution:

• Patients with heart failure, renal insufficiency, or liver disease should not drink large amounts of water.
• When upper respiratory infection patients are dehydrated, in addition to replenishing fluids, it is important to supplement sufficient electrolytes. You can add an appropriate amount of electrolytes to boiled water or drink bottled electrolyte beverages directly.
• Upper respiratory infection patients should drink more water, but avoid consuming large amounts at once. Instead, drink intermittently—one cup (about 300 ml) at a time—and wait a while before drinking again. This maintains hydration without overburdening the kidneys.

Can you exercise during an acute upper respiratory tract infection?

This depends on the specific situation.

• A small number of patients with good physical fitness and mild symptoms may continue exercising, but avoid intense activities to prevent additional strain on the heart.
• For elderly, frail, or chronically ill patients, exercise may worsen cardiopulmonary strain and even lead to severe cardiopulmonary insufficiency. Therefore, it is recommended to suspend exercise and rest more.
• After recovery, moderate exercise can help boost immunity and prevent recurrent infections.

Can you drive after taking cold medicine for an acute upper respiratory tract infection?

This depends on the circumstances. Most cold medicines on the market are compound preparations, often containing antihistamines to relieve symptoms like sneezing and runny nose. However, common side effects of these drugs include drowsiness and fatigue, so driving should be avoided while taking antihistamine-containing cold medicine^[6].

PREVENTION

How to Prevent Acute Upper Respiratory Tract Infections?

• Frequent handwashing is the most effective method^[1].
• During outbreaks of upper respiratory infections, avoid crowded, poorly ventilated public places and wear masks, especially for young children, the elderly, pregnant women, and those with weakened immune systems^[1,2].
• Exercise regularly, maintain a balanced lifestyle, improve nutritional status, and boost immunity.
• Avoid factors that may trigger infections, such as getting caught in the rain, overexertion, or smoking. Adjust clothing according to sudden weather changes.

How to Wash Hands Properly to Prevent Acute Upper Respiratory Tract Infections?

Research shows that proper hand hygiene can prevent the spread of respiratory viruses, especially transmission from young children to others.

The currently recommended "7-step handwashing technique" focuses on cleaning seven key areas of the hands, as follows^[9]:

1. Rub palms together to clean the palms.
2. Rub the back of one hand with the palm of the other, cleaning the back of the hand and fingers.
3. Interlace fingers and rub to clean between fingers.
4. Bend fingers and rub knuckles against the opposite palm to clean the back of fingers and nails.
5. Hold one thumb with the opposite hand and twist to clean the thumb and webbing.
6. Rub fingertips against the opposite palm to clean nails and fingertips.
7. Hold one wrist with the opposite hand and twist to clean the wrist.

These seven steps ensure no area is missed during handwashing. Additionally, this method provides sufficient time to effectively remove bacteria and viruses from the hands. If unsure about the duration, singing the "Happy Birthday" song twice is a good timing reference.