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What Causes a Sore Throat?

Andrew Bellingham

Andrew Bellingham

Pharmacist | 20+ Years | BPharm | Dip Clin Pharm

A sore throat, also known as pharyngitis, is discomfort, scratchiness or pain in the throat often worsened by swallowing. It can stem from viral or bacterial infections, allergies and other irritants. 

Severe sore throat pain may indicate bacterial infections like strep throat, with symptoms such as fever and swollen lymph nodes. Viral infections, however, typically involve additional signs like coughing or congestion.

Causes of Sore Throat

Though sore throats are usually caused by common viral infections, there are a variety of other triggers that can cause a sore throat.

Viral Infections

These viruses are the most common cause of a sore throat and can cause inflammation in the throat lining, resulting in discomfort and pain:

  • Influenza (the flu) 
  • Glandular fever

Bacterial Infections

Though bacterial infections are less common, they can also lead to severe discomfort and soreness in the throat.

Strep throat:

Strep throat is a contagious bacterial throat infection, which causes sore throat, difficulty swallowing and other painful symptoms. 


Tonsillitis is an infection which cause your tonsils to swell, it is usually caused by a viral infection (like the common cold or flu) and leads to a sore throat, difficulty swallowing, fever and generally feeling unwell. 

Sinus infections:​

Sinusitis is swelling of the sinuses, usually caused by a viral infection (like the common cold). It causes a sore throat due to post-nasal drip – which is excess mucus draining through the back of your throat.


These common allergies can also irritate and inflame your throat: 

Environmental Factors

These environmental factors can exacerbate throat irritation, and often result in a chronic sore throat (that lasts for a long time). 

Dry air:

The air you breathe can lack moisture, especially heated indoor environments during the winter months. Dry air can absorb the moisture from your sinuses and the lining of your throat, leaving you with a dry, scratchy sore throat.

Smoke (cigarettes or other sources):

Smoking exposes your throat directly to harmful chemicals and irritants which can give you a constantly sore throat. Most people feel better after quitting for a month.

Pollutants (vehicle emissions or industrial pollutants):

Breathing polluted air can make you more susceptible to bacterial and viral throat infections which cause sore throats. If you live in a heavily polluted city, an air purifier can help ensure you stay healthy.

Types of Sore Throat

There are several forms of sore throat that differ in cause, severity and duration:

Throat irritation or discomfort:

A scratchy, dry, or raw sensation in the throat, typically without significant swelling or redness. It may result from factors such as dry air, allergens, or mild viral infections.

Sore and swollen throat:

A sore throat with visible swelling and redness (inflammation) at the back of the throat

Bacterial or viral sore throat:

Bacterial sore throats usually have more severe symptoms, while viral sore throats tend to get better by themselves. 

Frequent Questions on Sore Throats

What is a scratchy throat?

A scratchy throat is a common sore throat symptom characterised by irritation or discomfort in the throat, often caused by dry air, allergies, or mild infections.

Can a sore throat make you feel sick?

Yes, a sore throat can make you feel sick. It’s a common condition usually caused by a viral or bacterial infection, leading to a painful throat and difficulty swallowing.

What is a strained throat?

A strained throat refers to a condition where the muscles in the throat are overworked or injured, typically due to excessive vocal strain or physical exertion.

A woman holds her sore throat while holding a cup of green tea in the other hand

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