Aphthous ulcers, commonly known as canker sores, are painful, shallow lesions that develop on the soft tissues inside the mouth. Unlike cold sores, these ulcers are not caused by a virus and are not contagious. A canker sore typically presents as a round or oval lesion with a white or yellow center surrounded by a bright red border.
Canker sores can appear on the soft palate, tonsillar pillars, or the pharynx, which is the back of the throat. When they occur in these deeper locations, it often indicates a less common and more severe presentation of the condition.
Where Aphthous Ulcers Form
Aphthous ulcers most frequently form on the non-keratinized, or softer, tissues of the mouth that are not tightly bound to bone. Typical locations include the inside of the cheeks and lips, the floor of the mouth, and the sides or underside of the tongue. The vast majority of cases (about 80%) are Minor Aphthous Ulcers, which are small (less than 5 millimeters in diameter) and heal without scarring within two weeks.
When canker sores appear toward the back of the mouth, they are often classified as Major or Herpetiform Aphthous Ulcers. Major ulcers are larger, often exceeding 10 millimeters, and are deeper, allowing them to affect areas like the oropharynx. These larger lesions can take several weeks to a few months to heal and may result in scarring due to the depth of tissue damage.
Herpetiform ulcers account for the smallest percentage of cases and also have the potential to affect the throat area. This type is characterized by small, pinpoint-sized ulcers that appear in clusters of ten to one hundred lesions. These clusters can sometimes merge to form one large, irregular ulcer, creating widespread discomfort.
Common Triggers and Causes
The exact cause of aphthous ulcers remains unclear, but they are thought to result from a T-cell-mediated immune response targeting the oral lining. Many factors trigger an outbreak in susceptible individuals, often beginning with minor physical trauma. This trauma includes accidentally biting the cheek, irritation from hard or sharp foods, aggressive toothbrushing, or recent dental work.
Emotional stress and hormonal shifts, such as those related to the menstrual cycle, are frequently cited factors that can precede an outbreak. Dietary factors also play a role, as sensitivities to acidic, spicy, or abrasive foods like citrus, coffee, or nuts can provoke ulcer formation. Deficiencies in micronutrients, including Vitamin B-12, iron, zinc, and folate, have also been associated with recurrent canker sores.
Other Sores That Mimic Canker Sores
A sore in the back of the throat is an atypical presentation for a common canker sore, making it important to consider other conditions that cause similar lesions. One common mimic is an outbreak caused by the Herpes Simplex Virus (HSV), which causes cold sores. HSV lesions typically present as small, fluid-filled blisters that appear on the hard palate, gums, or lips, which are areas of tightly bound, keratinized tissue.
Hand, Foot, and Mouth Disease (HFMD), a viral illness often caused by the coxsackievirus, is another frequent cause of throat lesions, particularly in children. HFMD usually begins with a fever and sore throat, followed by painful blisters or ulcers in the mouth and throat. This is often accompanied by a rash on the palms of the hands and soles of the feet. These oral ulcers are often described as yellow-grey with red edges, making them visually similar to canker sores.
Strep throat, a bacterial infection, is a possibility when severe throat pain is present, though it does not typically cause the classic white-centered ulcers. Strep throat is characterized by a rapidly onset sore throat, fever, and red, swollen tonsils that may have white patches, spots, or streaks of pus. Tiny red spots called petechiae may also appear on the soft palate, which can be mistaken for a lesion.
Home Remedies and Medical Consultation
For minor ulcers, the goal of home treatment is to reduce pain and inflammation while protecting the exposed tissue to promote healing. Rinsing the mouth with a solution of salt water or a baking soda rinse can help neutralize irritating acids and soothe the area. A paste made from baking soda mixed with water can also be gently applied to the lesion to provide a protective coating.
Over-the-counter topical treatments, such as gels or liquids containing benzocaine or lidocaine, can numb the area. For a sore in the back of the throat where direct application is difficult, a protective mouthwash or a milk of magnesia rinse can offer relief by coating the lesion and neutralizing acid. Avoiding abrasive, spicy, or acidic foods during the healing process is helpful, as these substances can worsen the pain.
A medical professional should be consulted if an ulcer is unusually large or deep, or if the pain interferes with eating or drinking. Seek professional evaluation if the sore lasts longer than two weeks, if new sores develop before old ones have healed, or if the sore is accompanied by systemic symptoms such as a high fever. Recurring outbreaks or signs of infection, such as increased swelling or pus, also warrant a medical visit.