Aphthous ulcers, or canker sores, are a frequent source of oral discomfort. These non-contagious ulcers typically appear as small, painful lesions inside the mouth. While they are most often found on movable tissues like the inner cheeks, lips, and tongue, their presence elsewhere can cause confusion about other throat conditions. Understanding the nature of these sores helps clarify why a painful spot in the back of the throat might be an aphthous ulcer rather than a bacterial or viral infection.
The Nature of Aphthous Ulcers
Canker sores are characterized by a distinct appearance: a round or oval ulcer with a white or yellow center surrounded by a bright red border. The most common type, Minor Aphthous Ulcers, are generally less than five millimeters in diameter and heal within one to two weeks without scarring. They are not caused by a virus and are not contagious, unlike herpetic lesions or cold sores.
The causes of these ulcers are not fully understood, but they are linked to an immune system reaction triggered by various factors. Common triggers include minor trauma, stress, acidic or abrasive foods, and nutritional deficiencies (such as a lack of Vitamin B12, iron, or folate). Herpetic lesions, conversely, are caused by the Herpes Simplex Virus (HSV) and typically appear outside the mouth on the lips, starting as a cluster of small, fluid-filled blisters.
Canker Sores in the Posterior Pharynx
Aphthous ulcers can develop in the posterior pharynx, including the soft palate, the back of the throat, and the tonsils. This location is less common than the inner lips or cheeks, but when it occurs, it can cause severe pain and be mistaken for other throat illnesses. A canker sore on a tonsil often presents as a single, painful lesion, sometimes causing a sore throat sensation on only one side.
When canker sores appear in this area, they may be the more severe types, such as Major Aphthous Ulcers. These are larger, often exceeding ten millimeters, deeper, and can take four weeks or longer to heal, sometimes leaving a scar. The constant movement of throat tissues during speaking and eating irritates the exposed ulcer, causing heightened discomfort and difficulty swallowing (dysphagia). Another variant, Herpetiform Aphthous Ulcers, presents as a cluster of numerous tiny ulcers that can merge into a single large, painful sore.
Differentiating Ulcers and Sores Near the Tonsils
Identifying a canker sore near the tonsils requires careful differentiation from other common causes of throat pain and lesions. A true canker sore in this area typically appears as a solitary, white or yellow ulcer with a defined red border and is not usually accompanied by general cold symptoms.
Viral Infections
Viral pharyngitis, or a common sore throat, is often accompanied by symptoms like a cough, runny nose, and generalized body aches. Ulcers caused by viruses, such as Coxsackievirus (Hand, Foot, and Mouth Disease), usually appear as widespread small blisters that quickly burst. These viral ulcers can affect the hard palate and gums, areas canker sores typically avoid.
Bacterial Infections and Inflammation
Strep throat, a bacterial infection, rarely causes ulcers but is characterized by a sudden onset of sore throat, fever, and white patches on both tonsils without a cough. Tonsillitis is inflammation of the tonsils caused by a virus or bacteria, resulting in swelling. The presence of a distinct, round ulcer, however, suggests an aphthous lesion.
Traumatic Ulcers
Traumatic ulcers are caused by physical injury, such as from sharp food or rough dental work. They are identifiable by a clear history of trauma preceding the sore’s appearance.
Management and When to Seek Medical Attention
Management for canker sores near the tonsils focuses on pain relief and promoting healing. Over-the-counter topical anesthetics (like benzocaine or phenol) can numb the sore if reachable, though a prescribed mouth rinse may be more effective for throat lesions. Simple home remedies, such as rinsing with a warm saltwater solution or a mixture of baking soda and water, can help soothe the irritation.
It is helpful to avoid abrasive, spicy, or acidic foods and drinks, as these can irritate the sore and prolong healing. While most minor canker sores heal within two weeks, a medical consultation is necessary in specific instances. These signs could indicate a secondary infection, an underlying health condition, or a more severe type of ulcer requiring prescription treatment.
You should seek attention if:
- The sore lasts longer than two weeks.
- You develop a high fever.
- The pain prevents you from eating or drinking.
- The lesions are unusually large or rapidly spreading.