A sore throat is a common symptom, often making it challenging to determine the cause without professional help. Strep throat, caused by Group A Streptococcus bacteria, accounts for only a small percentage of sore throats. Most cases of pharyngitis, or throat inflammation, are caused by viruses like those responsible for the common cold or flu. Understanding the differences between bacterial strep and viral infections is key to appropriate care. Symptoms, speed of onset, and visual presentation inside the mouth offer important clues for differentiation.
How Strep Symptoms Differ from Viral Illness
Strep throat and viral sore throats have distinct symptom profiles. A strep infection typically begins abruptly, often with rapid onset of throat pain that can become severe within hours. This contrasts sharply with a viral sore throat, which usually develops gradually over a few days.
A high fever, often reaching 100.4°F (38°C) or higher, frequently accompanies strep throat. Systemic symptoms like headache, stomach pain, and nausea or vomiting are also common, especially in children. Strep throat rarely affects the lower respiratory tract, so the absence of a cough, runny nose, or congestion is a strong indicator that the infection may be bacterial.
Viral sore throats are usually part of a larger constellation of cold or flu symptoms. If a sore throat is accompanied by a cough, hoarseness, pink eye (conjunctivitis), or a runny nose, the cause is highly likely viral. The sudden, severe pain and lack of cough associated with strep are often the initial differentiating factors.
What to Look For Inside the Mouth
Observing the back of the throat provides further distinguishing signs. Strep throat typically causes the tonsils to become visibly swollen and bright red. A telltale sign is the presence of white patches or streaks of pus, known as exudate, directly on the tonsils.
Another visual indicator specific to strep is the appearance of tiny, pinpoint red spots, called petechiae, on the soft or hard palate at the roof of the mouth. In some cases, particularly with scarlet fever, the tongue may develop a unique “strawberry” appearance. This involves an initial white coating that peels away to reveal a shiny, bright red surface with enlarged bumps.
A viral sore throat, in contrast, usually presents as generalized redness and inflammation throughout the throat. While viral infections can cause mild redness, they rarely result in the specific white pus patches, petechiae on the palate, or the characteristic strawberry tongue seen with strep.
When Medical Testing Becomes Necessary
While the presence of high fever, rapid onset, and white patches on the tonsils strongly suggest a strep infection, visual inspection alone is insufficient for a definitive diagnosis. Many viral infections can mimic the visual signs of strep, and some people can carry the Streptococcus bacteria without showing any symptoms. Confirmation requires medical testing, usually a rapid strep test or a throat culture, to detect the presence of the Group A Streptococcus bacteria.
Seeking medical attention for testing is important because strep throat requires treatment with antibiotics, whereas viral sore throats do not. Antibiotics are necessary to eradicate the bacteria and prevent the spread of infection, but their most important function is to prevent non-suppurative complications. Untreated strep can lead to serious conditions that develop as an immune response to the bacteria, even after the initial throat infection has resolved.
These potential complications include acute rheumatic fever, which can cause inflammation and permanent damage to the heart valves and joints. Another serious immune-mediated complication is post-streptococcal glomerulonephritis, an inflammation of the kidneys. Antibiotic therapy, especially if started within nine days of symptom onset, is highly effective at preventing rheumatic fever. Any suspicion of strep based on the symptom profile warrants immediate medical evaluation.