A canker sore in the throat can be caused by periods of stress or intense emotions, but it can also be a result of a wound in the mouth that is healing, infection (like herpes) or medication use (like anti-inflammatories). When canker sores in the throat are very big and take a long time to heal, they can be a sign of a more serious disease such as AIDS or cancer.

A canker sore, or ulcer, is a small, round sore that is whitish in the middle and reddish on the outside. It causes pain and discomfort, especially when swallowing or speaking. In some cases, it can be accompanied by other symptoms such as fever, general malaise and swollen lymph nodes in the neck area.

You should see a doctor if your frequently experience canker sores in the throat, if they take long to heal, or if they are accompanied by other symptoms like fever and weight loss. The doctor may prescribe ointments for to treat a throat ulcer and suggest the elimination of acidic foods from your diet. Another common recommendation is gargling warm water with salt to help relieve discomfort.

Why do I have a canker sore in my throat?

Canker sores in the throat can be caused by:

1. Aphthous stomatitis

Canker sores in the throat from aphthous stomatitis are not linked to a specific cause, and are generally associated with pain. They tend to emerge following small mouth wounds, periods of stress and menstruation.

Furthermore, an iron or B12 deficiency, allergies to oral products (like tooth paste) and foods (like citric fruit and cinnamon) can cause aphthous stomatitis.

How to treat: Throat ulcers from this condition usually resolve on their own within 3 weeks, without any specific interventions. However, You should see a doctor if you have intense pain or have difficulty breathing. The doctor may prescribe ointments with anesthetic and corticosteroid properties to relieve pain.

2. Herpes

The virus that causes oral herpes can also cause painful ulcers in the throat, tongue or top of the mouth in addition to the usual blisters around the lips.

These symptoms may be accompanied by fever and general malaise when the infection occurs for the first time. Recurrences will usually cause more mild symptoms.

How to treat: Canker sores in the throat caused by herpes tend to improve within 2 weeks without any specific treatment. However, if symptoms like fever, malaise or intense pain occur, you should see a doctor to confirm a diagnosis. The doctor may prescribe cold sore medicines like antivirals or analgesics to reduce symptoms and speed-up recovery.

3. COVID-19

COVID-19 is a viral infection caused by the SARS-CoV-2 virus. It can cause canker sores in the throat due to factors like intense inflammation and the virus’ direct effect on the oral mucosa.

Other more classic symptoms of this infection include coughing and fever. Check-out the other symptoms of COVID-19 and how it is transmitted.

How to treat: It is important to consult a family doctor, lung specialist or infectious disease specialist if you suspect you may have COVID-19. The doctor may prescribe acetaminophen or antivirals, although more severe cases may require treatment in a hospital setting.

4. Medication use

The use of some medications, mainly non-steroidal anti-inflammatories (like naproxen), anti-hypertensives (like losartan) and chemotherapy medications may lead to canker sores in the throat as a side effect.

How to treat: You should avoid using these medications unless indicated by a doctor. If prescribed, they should be taken only as instructed. If you suspect your canker sores are related to medications, you should consult your prescriber to reevaluate dosing or consider an alternative medication.

5. Systemic lupus erythematosus

A throat ulcer caused by systemic lupus erythematosus can occur in areas like the throat, tongue, roof of the mouth or lips. It is also common to notice weight loss, decreased mood and joint pain with this condition.

Learn more about the symptoms of lupus and what can cause this condition.

How to treat: If you suspect you may have systemic lupus erythematosus, you should consult a rheumatologist. These canker sores tend to improve with treatment of the overall condition, which may involve oral corticosteroids and anti-malarials.

6. HIV infection

HIV can cause one or more canker sores in the throat that are large, painful and take a long time to cure. This is especially true for patients who are not receiving or adhering to adequate treatment.

Although an HIV infection can cause minimal symptoms in the beginning, if left untreated, it significantly affect immunity and increase the risk for infections.

How to treat: It is important to consult a family doctor or infectious disease specialist if you think you may have HIV. If confirmed, the throat ulcers will typically improve with general HIV treatment, which may involve antiviral medications.

7. Oral cancer

Oral cancer can cause canker sores in the throat or several throat wounds that are difficult to heal. Depending on the extent of the tumor, other symptoms can emerge, like difficulty swelling, hoarseness, weight loss and swollen lymph nodes along the neck.

How to treat: Oral cancer should be assessed by a doctor if suspected. Diagnosis is confirmed with a biopsy of the lesion. Treatment may include surgery to remove the tumor, radiation therapy and chemotherapy.

If you get a canker sore in the throat more than once a month, or if two outbreaks of ulcers happen within less than a week of each other, you should see your family doctor for blood tests that can help identify what may be causing the problem. Once the diagnosis is made, appropriate treatment is started so as to prevent the sore from appearing again.

Other situations that may cause small sores in the throat are tonsil stones, tonsillitis, and aphthous stomatitis, which are more common in infants.

Treatment options

Treatment for canker sores in the throat can be completed with combination corticosteroid and anti-inflammatory ointments, or with topical anesthetics (e.g. xylocaine 5%). These are prescribed by a doctor and applied with a finger or with the help of a cotton swab.

Other drugs that can be used to relieve pain caused by throat ulcers are acetaminophen or ibuprofen, and should be used as recommended by a doctor. Laser treatments can be used if the throat sore is greater than 1 cm in diameter or if the sore is causing difficulty with eating or drinking.

Speed-up throat ulcer healing

To help heal canker sores in the throat, some precautions should be considered, such as:

Rinsing your mouth with mouthwash after brushing your teeth, as this can help to eliminate bacteria and cleanse the area
Avoiding acidic foods like lemon, pineapple, tomato, kiwi and orange, as the acidity can increase pain
Eating more foods rich in B complex vitamins, folic acid and iron such as banana, mango, low-fat yogurt or apple juice (vitamin deficiency can cause throat ulcers)
Gargling warm water with salt or gargling hydrogen peroxide diluted in water, as they are antiseptic and clean the area. To prepare the solution, simply add 1 tablespoon of salt into 1 cup of warm water or 2 tablespoons of hydrogen peroxide 10 volumes in 1 glass of water. Check out other gargle recipes you can use at home to relieve a sore throat.
Avoid worsening by not eating hard or crunchy foods such as toast, peanuts, nuts
Using a toothbrush with soft bristles;
Avoid oral hygiene products with irritating ingredients like sodium lauryl sulphate.

If you follow treatment as directed by your doctor while keeping these recommendations in mind, canker sores in the throat will likely disappear on their own within a few days.

If you are also experiencing mouth ulcers, check out natural ways to speed-up healing at home.

When to worry

When canker sores appear frequently in the throat (e.g. more than 6 times a year) you should see a doctor for assessment, especially if you have other symptoms. Testing that may be ordered includes:

Complete blood count
Iron, ferritin and iron uptake, vitamin B12 levels
HIV antibodies, viral cultures and biopsy.

However, there is usually no need to request these exams and they are generally done when the canker sores are difficult to control.