Common Causes of Sore Throat

From Infection and Injury to Irritants and Disease

Young woman touching her neck in pain
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The throat is an easy target for infection and injury, perhaps more than any other part of the body. It is the instrument through which food and air pass, and that alone provides the opportunity for disease-causing agents to reach and breach otherwise vulnerable tissues.

And, because it is key to respiration, the throat is often unable to escape the effects of environmental toxins and can even be damaged by environmental changes (such as excessive dryness or exposure to seasonal allergens).

Conversely, a reversal of digestive or respiratory function, such as can happen with acid reflux or chest infection, places the throat under enormous stress, both direct and indirect. Even the simple act of shouting can injure the throat, causing pain, inflammation, and long-lasting injury to the vocal cords.

Understanding Pharyngitis

A sore throat is an everyday term used to describe pharyngitis (the inflammation of the pharynx). The pharynx is the cavity behind the nose and mouth that leads to stomach and lungs. Typically symptoms of pharyngitis include a scratchiness in the throat and difficulty swallowing (dysphagia).

While most people will know the cause of their sore throat, either because of an accompanying symptom or and identifiable injury, others may require a doctor to make the diagnosis. As with other commonplace symptoms such as headache or sneezing, a sore throat may mean something or nothing; it all depends on the nature of the illness.

Herein are the most typical causes of sore throat, ranging from minor, localized infections to more serious systemic disease:

Bacterial Infections

A number of bacterial infections can cause a sore throat. One of the most common is Streptococcus pyogenes, the bacteria associated with strep throat (streptococcal pharyngitis).

Strep throat is relatively minor but can sometimes lead to more severe infections. In addition to the typical signs of pharyngitis, symptoms can include nausea, vomiting, a foul breath, and the visible inflammation of the throat.

Less common bacterial throat infections include Neisseria gonorrhoeae (gonorrhea), Bordetella pertussis (whooping cough), bacterial tonsillitis, and bacterial pneumonia. Diagnosis of a bacterial infection is typically made on a throat culture, while treatment involves the use of appropriate antibiotics.

Viral Infections

Viral infection accounts for more than half of all pharyngitis cases. Of these, the common cold is the predominant form of illness. The common cold is caused by over 200 types of virus, including adenoviruses, rhinoviruses, and coronaviruses. Sore throat symptoms are typically accompanied by nasal congestion, sneezing, runny nose, headache, and fever. Tonsillitis can also develop.

Other viral infections associated with pharyngitis include:

While certain viral infections, like HSV, can be treated with antiviral drugs, many others (including measles, mononucleosis, and the common cold) have no cure.

Fungal Infections

The most common cause of fungal throat infections is Candida albicans, a type of yeast which causes both oral thrush and yeast infection. Infection tends to occur in people with suppressed immune systems with the most severe cases often seen in people with advanced HIV infection.

Oral thrush (oral candidiasis) can often be symptom-free but, in some cases, can lead to soreness of the mouth, tongue, and throat. When it involves the esophagus, candidiasis is considered serious. Fungal infections like these are treated with antifungal medications.

Allergic Pharyngitis

Allergic pharyngitis is the inflammation of throat caused by primarily by an allergen that enters the nose or mouth.

A sore throat is often secondary to the primary symptoms of the allergy, which can include acute sinusitis, rhinitis (stuffy nose), and breathing difficulties. A persistent nasal drip may also add to the inflammation.

In some cases, an allergy might directly the throat. We tend to see this is cases of anaphylaxis, a potentially life-threatening reaction to certain medications (such as penicillin), foods (peanuts), or insect stings. Depending on the severity of the response, symptoms may include a sore throat, rash, fever, and difficulty breathing or swallowing. In more severe cases, it can lead to the constriction of the throat, nausea, vomiting, respiratory failure, shock, and even death.

Acid Reflux and GERD

Acid reflux occurs when stomach acid or bile backs up toward the throat. Both of these digestive fluids are irritating to the mucosal lining of the pharynx and esophagus. Symptoms include indigestion, heartburn, burping, bloating, regurgitation abdominal pain, and a burning sensation in the throat. Treatment involves the use of medications to reduce or neutralize stomach acid, including antacids and proton pump inhibitors.

While acid reflux may be the direct result of something we've eaten or drank, it may also be a persistent condition we commonly refer to as gastroesophageal reflux disease, or ​GERD.

Irritants and Toxins

Exposure to certain substances can cause the direct inflammation of the pharynx and associated organs. Some are inhaled irritants like air pollution, cigarette smoke, and industrial fumes. Others are related to foods and other substances we ingest, such as alcohol, spicy foods, or chewing tobacco. Even dry air can be considered an irritant insofar as the lack of humidity (caused by arid climates or excessive air conditioner use) can leave a throat feeling dry and scratchy.

While some irritants are environmental and largely unavoidable, others like smoking are modifiable, meaning that we can choose to stop them and alleviate many of the chronic symptoms.

Other Conditions

Pharyngitis can be caused by any number of other conditions. Other possible causes include:

  • mouth breathing, especially when sleeping
  • direct throat injury
  • muscle strain caused by talking loudly or for long periods of time
  • benign vocal lesions caused by overuse or trauma to vocal cords
  • epiglottitis (inflammation of the cover of the windpipe)
  • peritonsillar abscess (a complication of tonsillitis)
  • throat cancer
  • antipsychotics and other drugs (such as pramipexole used to treat Parkinson's)


Hildreth, A.; Takhar, S.; Clark, M.; and Hatten, B. "Evidence-Based Evaluation And Management Of Patients With Pharyngitis In The Emergency Department.". Emergency Medicine Practice. 2015: 15(9): 1-16