Tonsillitis is an inflammation of the tonsils, which are small masses of lymphoid tissue located on both sides of the throat (pharynx). These tonsils play an important role in the immune system during childhood, helping the body recognize and fight off infections. When the tonsils become infected or irritated, they swell, redden, and may become painful. Tonsillitis can be acute, which means it develops suddenly and usually lasts a short time, or chronic, which means the inflammation persists over a long period or keeps returning repeatedly.
Acute tonsillitis, often referred to as angina, typically appears after exposure to infectious agents such as viruses or bacteria. On the other hand, chronic tonsillitis generally develops as a consequence of repeated bouts of acute tonsillitis or after certain infectious diseases, such as scarlet fever, measles, or diphtheria. These illnesses may weaken or damage the mucous membrane of the throat, making it easier for bacteria to persist within the tonsils. In some individuals, chronic tonsillitis may form independently, without a clear history of previous infections, particularly if the person has weakened immunity or prolonged exposure to irritants.
Various factors contribute to the development of tonsillitis. One significant factor is microbial allergy, which refers to an exaggerated immune response to microorganisms such as streptococci or adenoviruses. In these cases, the immune system becomes overly reactive to the presence of such pathogens, leading to recurring inflammation in the tonsillar tissue. Chronic tonsillitis often involves persistent ulceration of the mucous membrane, formation of pus-filled pockets within the tonsils, and excessive growth of connective tissue, which gradually alters the structure and function of the tonsils. Over time, these changes reduce the tonsils’ ability to fight infections effectively.
What Causes Tonsillitis?
In the majority of cases, tonsillitis is triggered by viral infections. Common viruses responsible for this condition include cold viruses, influenza viruses, adenoviruses, and others that frequently circulate during the winter or periods of reduced immunity. Viral tonsillitis tends to resolve on its own and is often accompanied by symptoms such as runny nose, cough, sore throat, and fatigue. However, viral infections sometimes weaken the mucous membranes, which then become more vulnerable to bacterial invasion.
Although viruses are the most frequent cause, bacterial tonsillitis also occurs, and it is especially associated with Streptococcus pyogenes, also known as Group A Streptococcus. This bacterium can cause severe acute tonsillitis characterized by high fever, intense throat pain, difficulty swallowing, swollen lymph nodes, and visible white patches or pus on the tonsils. Strep tonsillitis must be treated with antibiotics, as untreated cases can lead to serious complications such as rheumatic fever, kidney inflammation (glomerulonephritis), or abscess formation around the tonsils.
How Tonsillitis Develops
The tonsils act as the first line of defense against pathogens entering through the mouth and nose. When viruses or bacteria reach the tonsils, the immune system activates white blood cells in the lymphoid tissue. This immune reaction causes swelling, redness, and sometimes the accumulation of pus. In acute infections, these changes occur rapidly, causing sudden sore throat, fever, and difficulty swallowing. If the tonsils repeatedly encounter infectious agents or if the immune response remains constantly activated, the inflammation can become chronic.
Chronic tonsillitis often results from incomplete healing of previous infections. Bacteria can remain trapped deep within the tonsillar crypts—small natural pockets within the tonsils—making it difficult for the body to eliminate them. Over time, these bacteria may form biofilms, which are layers of microorganisms that are resistant to antibiotics and immune attacks. As a result, the inflammation becomes persistent or recurrent.
Symptoms of Tonsillitis
Tonsillitis presents with a variety of symptoms, depending on whether the cause is viral or bacterial, and whether the inflammation is acute or chronic. Common symptoms include:
Sore throat, often severe
Red and swollen tonsils
White or yellow patches or pus on the tonsils
Fever and chills
Pain when swallowing
Bad breath due to bacterial activity
Swollen lymph nodes in the neck
Hoarse voice or difficulty speaking
Tiredness and general weakness
Chronic tonsillitis may present differently. Instead of intense pain, individuals often experience persistent throat irritation, frequent bad breath, recurrent sore throats, and a constant feeling of something stuck in the throat. These symptoms may be milder but longer lasting.
Risk Factors
Several factors increase the risk of developing tonsillitis:
Frequent exposure to infected individuals, especially children in schools
Weak immune system
Seasonal viral outbreaks, such as in winter
Allergies or microbial hypersensitivity
Chronic sinus problems, which can cause persistent post-nasal drip
Smoking or secondhand smoke, which irritates the throat and reduces local immunity
Complications
If not properly treated, tonsillitis can lead to complications. One of the most serious is peritonsillar abscess, a large pus-filled swelling that forms around the tonsil and can make swallowing or breathing difficult. Bacterial tonsillitis caused by Group A Streptococcus can also cause systemic complications such as rheumatic fever, which affects the heart, joints, and nervous system, or post-streptococcal glomerulonephritis, a serious kidney condition.
Chronic tonsillitis can negatively affect quality of life by causing constant discomfort, recurrent infections, or enlarged tonsils that may interfere with breathing during sleep, leading to sleep apnea.
Summary
Overall, tonsillitis is a common condition primarily caused by viral infections, though bacterial infections—especially streptococcal—can produce more severe symptoms and require antibiotic treatment. Chronic tonsillitis often develops after repeated infections or as a result of microbial allergy, gradual structural changes, and persistent bacterial presence within the tonsils. Understanding the causes, symptoms, and possible complications is essential for preventing repeated episodes and ensuring proper management.
