Strep throat is a common infection of the tonsils and throat caused by the bacterium Group A Streptococcus (GAS). While antibiotics usually treat the illness, the primary reason for seeking treatment is not just symptom relief. Prompt diagnosis and treatment are necessary to prevent the bacteria from triggering severe, delayed reactions in the body. Understanding the potential consequences of untreated strep throat explains why timely medical intervention is recommended.
Prolonged Symptoms and Localized Infections
Leaving a GAS infection untreated allows the bacteria to multiply and prolong the period of severe symptoms. Adults may experience an extended duration of intense throat pain, fever, and difficulty swallowing. The body’s immune system will eventually clear the infection, but during this time, the bacteria can spread to surrounding tissues.
The most common localized complication is a peritonsillar abscess, a pocket of pus that forms near one of the tonsils. This abscess causes a dramatic worsening of symptoms, including severe, typically unilateral, throat pain and a muffled voice often described as a “hot-potato voice.” As the swelling progresses, the ability to open the mouth fully (trismus) and swallow saliva can become restricted.
The Risk of Systemic Autoimmune Responses
The most serious consequences of untreated strep throat are not caused by the bacteria itself but by a delayed, misguided immune response. These systemic complications occur when the body’s antibodies, created to fight the GAS bacteria, mistakenly begin to attack the body’s own tissues.
One of the most concerning delayed reactions is Acute Rheumatic Fever (ARF), which usually appears two to four weeks after the initial throat infection has resolved. ARF is a widespread inflammatory condition that can affect the joints, skin, brain, and, most dangerously, the heart. The inflammation of the heart tissue (carditis) can lead to permanent scarring and damage to the heart valves, known as Rheumatic Heart Disease.
Symptoms of ARF often include migratory arthritis, where pain and swelling move from one large joint to another, such as the knees, ankles, or elbows. In some cases, the condition can also cause Sydenham chorea, which involves involuntary, jerky movements of the limbs and face. A different strain of GAS can trigger Post-Streptococcal Glomerulonephritis (PSGN), which is inflammation of the filtering units in the kidneys. PSGN typically develops one to three weeks after the throat infection, leading to symptoms like generalized swelling (edema), high blood pressure, and reduced urine output.
How Antibiotics Prevent Severe Outcomes
Antibiotics work by rapidly eradicating the Group A Streptococcus bacteria from the throat. This swift elimination is important because it prevents the bacteria from persisting long enough to trigger the harmful autoimmune cascade. The goal of treatment is to remove the antigenic material that primes the body’s immune system to attack its own tissues.
For the prevention of Acute Rheumatic Fever, antibiotic treatment is highly effective and can be started up to nine days after the onset of symptoms. This timeframe provides a window of opportunity to neutralize the threat and prevent the initial attack of ARF. While this treatment window successfully prevents ARF, the same early intervention is not consistently proven to prevent Post-Streptococcal Glomerulonephritis. However, antibiotics do help to shorten the duration of the throat infection and prevent the development of localized complications like peritonsillar abscesses.
Signs Requiring Immediate Medical Care
While the majority of strep throat cases resolve uneventfully with treatment, certain signs indicate that the infection has progressed to a dangerous stage. Any adult who has had a sore throat should seek emergency care if new or worsening symptoms develop.
Signs of a severe localized infection include severe difficulty swallowing or breathing, excessive drooling, or an inability to fully open the mouth. Delayed systemic complications include new-onset joint pain that moves from joint to joint, unexplained skin rashes, or chest pain and palpitations. Kidney involvement may be signaled by swelling, especially in the face or ankles, or the presence of dark, rust-colored, or significantly reduced urine output.