frustrated ethnic man in casual wear on blue background in studio


I know how it feels to bear with a canker sore. You can’t enjoy the food. Can’t talk freely in public. Its irritating! Right?

Have you ever experienced a canker sore on the lip? How discomforting is it?

I have seen people trying all sorts of DIY to treat these ulcers. But do you know, canker sores heal themselves within a week?

Here are a few things you should know about canker sores. The common questions and misconceptions are also covered in this article. So, without wasting time, let us find answers.

Wait! there is a surprise in the end. Read till the end and avail the surprise.

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What are canker sores?

Canker sores are common ulcers that occur in the mouth. They range from multiple tiny ulcers (herpetiform aphthous ulcers) to a sizeable solitary ulcer (major aphthous ulcer). The most common ulcers are the minor aphthous ulcers. They appear on soft parts of the oral cavity like cheek, tongue, and lips.

Aphthous ulcer in the floor of the mouth. Notice severe erythema around the ulcer.

Aphthous ulcers

The term Aphthous ulcers is a synonym for canker sores. It is a medical term to describe recurrent self-limiting ulcers in the oral cavity. According to the size and number they are usually classified as

  1. Major aphthous ulcers: They are large ulcers in the oral cavity with an extent greater than 2 Centimetres in diameter. Moreover, they are rare and seen in immune-compromised individuals. They take six weeks to heal.
  2. Minor aphthous ulcers: They are the most common ulcers that we usually see in the oral cavity. They occur in different regions and heal within a week.
  3. Herpetiform ulcers / herpetiform canker sores: Interestingly, these ulcers mimic herpes-a viral infection. As days pass, they fuse to form a single large ulcer. They are often misdiagnosed. They too heal within a span of a week to 10 days.

Causes of canker sores in the mouth

No one knows the exact reason for canker sores. But research shows stress as one of the main risk factors for developing canker sores.


Did you get a canker sore during your school or university days? Yes! Students are more prone to get canker sores during exams. An intimate relation between stress and canker sores is observed in the literature.

Stress and canker sores are associated. Some researchers found increased functioning of leukocytes (immune cells) during stress, which resulted in ulcers. While others consider increased cheek biting and teeth clenching can result in trauma and initiation of an ulcer.

Stress levels are more in females than in males. This could be one of the reasons to say that females are more prone to canker sores than males.

Vitamin deficiency

Vitamin deficiency is more in underdeveloped countries where people eat a less nutritious diet. Lack of vital vitamins like vitamin B3, Vitamin C, Vitamin B12 & folic acid is known to cause canker sores.

Altered immunity

Presence of aphthous ulcers is a sign of altered immune status in few patients. A change in cell-mediated immunity can trigger local break down of epithelial cells by lymphocytes causing ulcers.


Genetic involvement in canker sores can play a decent role. Researchers found up-regulation of Th-1 associated genes in canker sores. These genes result in activation of t-lymphocytes. The research found a hereditary factor in canker sores. Children with parents having canker sores have a 90% chance to develop the same.

Bechet’s disease

Bechet’s disease or syndrome is a group of disorders where the patient suffers from recurrent canker sores, ulcers in eyes and genitals.

Dental treatments

Patients often present with ulcers during dental treatments like root canal therapies. The ulcers are usually seen during the second sitting of RCT. Allergy from root canal medication can be suspected.

A thorough dental cleaning can produce a rough surface on the teeth. This increases friction between mucosal surface leading to Ulcerations.

Hormonal disturbances

Canker sores are seen more in women during pregnancy & menopause. This can be attributed to hormonal changes.

Presentation and symptoms

Canker sores appear as ulcerations with clear borders. They are covered with a pink to the yellow-coloured membrane called fibrin clot.

During the initial stage, canker sores appear as small bumps with a mild tingling sensation. Within 24 to 48 hours, they turn into ulcers. The ulcers are round in shape with symmetrical borders. The surrounding skin is healthy in appearance.

Patients with canker sores often complain of

  1. Pain while eating spicy food
  2. Burning sensation while brushing
  3. Unable to eat or drink hot food or beverages.
  4. Pain while stretching lips or while smiling (when ulcer forms on lips)

15 things you should know about canker sores


Canker sores are self-limiting. I have seen people trying various home remedies to cure these ulcers. But remember, you treat it or not, these ulcers are going to disappear within a week.

Recurrent aphthous stomatitis or Recurring canker sores :

Some patients get repeated episodes of these ulcers. This condition is called “RECURRENT APTHTHOUS ULCERS”. They are often misdiagnosed as herpes (a viral infection) because they usually occur on lips.

Blood investigations:

A recurrent canker sore is a condition that needs an oral physician’s attention. Hence visit your dentist. He may advise a few investigations and may prescribe medication. Co-operate with your dentist.

Persistent ulcers:

A persistent canker sore is a rare condition and should require a dentist’s review. The ulcers should not stay for more extended periods. But if such a presentation is seen, it needs immediate attention. Non-healing ulcers might turn out dangerous.

oral cancer
Persistent ulcer which turned into cancer

Canker sore on the lip

Lips are the most common regions for Aphthous. Ulcers on lips are more easily seen than any other lesions in the oral cavity. They interfere in speaking, eating and drinking. Patients with lip ulcers feel uncomfortable with spicy foods and hot fluids because of burning sensation.

People often misunderstand multiple Aphthous ulcers as herpes (cold sores) and think them to be contagious. But viral ulcers usually occur on hard mucosa like gums palate and corners of the mouth.

Ulcer on the lower lip.

Canker sore on tongue

Patients with tongue ulcers can’t enjoy food. They typically complain of altered taste sensation. Ulcers on tongue hamper free movement and interfere with normal speaking.

The ulcers are more commonly seen on the top surface of the tongue, followed by the side and tip region.

These ulcers are misdiagnosed as cancer ulcers. A biopsy can be a gold standard to conclude such confusion.

ulcer on tongue
Ulcer on the tongue due to severe & continuous trauma from teeth

Canker sore on gum

Canker sores on gums is a rare condition. Viral ulcers like herpes (cold sores) are commonly seen on gums. Hence ulcers on gums should be scrutinised before treatment.

Canker sores vs cold sores

People often confuse between canker sore and cold sore. A canker sore is a regular ulcer, while, cold sores are viral ulcers which are contagious.

Here are a few common things about canker sores and cold sores.

  • Both appear in the form of ulcers
  • Both ulcers are self-limiting and heal upon themselves. In most cases, the body’s immunity helps in decreasing these ulcers.

Here are a few points which help in differentiating canker sores from cold sores.

  • Canker sores usually occur inside the mouth, while cold sores occur in the corners of the lips (outside mouth).
  • Canker sores do not occur on gums and palate. In 90% of cases, ulcers seen on these two regions would be viral ulcers / cold sores.
  • Patients are healthy during canker sores, while, patients suffer from fever (prodromal symptoms) before cold sores.
  • The mucosa bearing ulcers appear normal in aphthous. But mucosa becomes inflamed and swollen in cold sores.
  • Canker sores require nutritional supplements like multivitamin tablets. Cold sores require antibiotic and antiviral therapies.
Cold sore in healing stage in the corner of mouth

Canker sore in throat/back of the throat

Canker sores rarely occur in the throat or end of the throat. It is cold sores which commonly occur in this place. Hence in case of an ulcer in the throat or back of the throat, it is wiser to consult a dentist rather than self-treatment.  The treatment protocol for canker sores is entirely different from cold sores.

Canker sores in the throat region usually appear as a small ulcer which is painful during eating. While cold sores in the same area produce a severe burning sensation. Such a condition is called pharyngitis.

Canker sore on the back of the throat (major aphthous)

Canker sore on tonsil

Ulcers often appear on the tonsils (surface of tonsillar crypts). But these ulcers are entirely different from canker sores. The condition is called tonsillitis, where the tonsils in the mouth become enlarged and infected. They are seen in children infected with various viral infections.

Are mouth ulcers a sign of covid?
Multiple ulcers involving throat and tonsils in coxsackie viral infection

Canker sore on roof of the mouth

Again! Canker sores in the roof of the mouth is a rare condition. It is a common site for cold sores (in 70% of cases) or viral ulcers followed by traumatic ulcers (in 20% of cases).

In other words, some patients have a habit of taking hot coffee or tea in the morning or try to brush their teeth with some abrasives like salt. Such patients often encounter traumatic ulcers in the roof of mouth or palate.

Hence, ulcers in such regions have to be thoroughly evaluated by an oral physician. Correct diagnosis and treatment aids in the prompt prognosis of the lesion.

Canker sore on the cheek

The most common site for canker sores is cheek followed by lips. In 90% of cases, the first appearance of canker sores is on the cheek.

Students during exams often complain of such canker sores.

Remember! Viral ulcers or cold sores never occur on the cheek.

Multiple canker sores

Number plays a crucial role in diagnosing the type of canker sore. A single large ulcer is usually seen in major canker sore / major aphthous ulcer. Such lesions are commonly seen in patients with less immunity. Digging more, I can say that these lesions are more often seen in HIV infected patients.

Few ulcers (2-5 ulcers) of size less than 1 cm in diameter are seen minor canker sores/ minor aphthous ulcers. These are the common type of canker sores that we speak off. The ulcers are usually self-limiting. Stress management and multivitamin supplements aid in fast healing of these ulcers.

Multiple tiny small ulcers (10-20 tiny ulcers) are seen in herpetiform canker sores/ herpetiform aphthous ulcers. They are rare in presentation and are often misdiagnosed as cold sores or viral ulcers. The help of a physician is must to diagnose ulcers in such condition.

Infected canker sore

Canker sores, in general, are not painful until they are infected. An infected canker sore is more erythematous and painful. They are often accompanied by pus discharge. These ulcers need immediate attention and should be treated with antibiotics.

Multiple infected canker sores are usually seen in patients with low immunity with severe malnutrition. In such conditions, we may see both canker and cold sores in the same person.

Canker sore in toddlers/kids

Canker sores are seen more in adults than in children. 90% of ulcers in children are either from viral infections (cold sores) or trauma (traumatic ulcers).

Ulcers in children are more infectious and need a doctor’s consultation.

Multiple ulcers are seen in a child with severe nutritional deficiency. Both canker and cold sores are observed

Get rid of canker sores in 7 steps

Canker sores are self-limiting. They disappear after 1 week. But patients with repeated canker sores can prevent recurrence by following these simple steps.

Maintain a healthy diet:

Diet rich in nutritional supplements helps in preventing a recurrence. Vitamin supplements like Vit B12, Vit B3, Iron and folic acid should be taken regularly.

Diet rich in omega fatty acids helps in decreasing inflammation of the mucosa, thus reducing the chance of ulcers.

Stress management:

Patients with repeated ulcerations can opt for stress reduction exercises like yoga and meditation. Both of them have given proved results in successful reduction of canker sores.


Toothpaste with low pH should be avoided. Gel pastes have more abrasives and have a decent chance to produce canker sores. Use bland white pastes with a neutral ph.


If you are allergic to some types of food. Better to avoid them. Allergic reactions may provoke ulcerations.

Hot and spicy food may aggravate canker sore formation. Avoid them until the ulcers are healed.

Grainy food increases abrasiveness in the oral cavity. Shift to a softer diet until the ulcers are healed. Cold food has the advantage of producing a soothing effect on ulcers when compared to hot or warm food.

Avoid food like chips, and roast which increase friction while eating.


Patients with cheek-biting habits have higher chances of canker sores. Cheek biting increases the frequency of ulcerations. Cheek biting aggravates aphthous but never causes them.

Patients with cheek-biting or teeth-clenching habits should be cautious during ulcerations. Slight negligence can traumatise the aphthous causing more damage and recurrences.


Medication can only produce symptomatic relief. They cannot cure canker sores. Most common medicines advised in treating canker sores are

  • Anesthetic creams provide a soothing effect. These creams come with benzocaine solutions which give numbness to the mucosa like Orajel canker cream.
  • Vitamin supplements for nutritional supply
  • Steroid creams for local application
  • Canker covers aid in forming a protective coat around the ulcer. They isolate ulcers from other irritants and help in fast healing. E.g. Dentek canker cover

Remember! Always use medication only after a dental consultation. I have seen people self-diagnosing cold sores like canker sores. It could worsen the condition.


Oral ulcers occur due to a variety of reasons. Identifying the exact cause of an ulcer is done only by professionals.

Professionals trained in Oral medicine have expertise in diagnosing and treating such oral ulcers. Hence ask your dentist to fix an appointment with an oral physician or Oral medicine expert.

After a thorough examination, your oral physician may come to a diagnosis and may advise the necessary treatment.

Natural Home remedies for canker sores

Managing canker sore is not a difficult task. There are a bunch of natural products that aid in the proper healing of these ulcers.

Aloe Vera

Aloe Vera has anti-inflammatory and antibiotic-like properties. Recent studies by Nada et al. have found that 2% of aloe Vera gel is effective in decreasing the wound healing period of these ulcers.

Aloe vera mouthwashes & creams can be useful in treating such ulcers due to their immunomodulatory effect.

Extract the gel from the aloe Vera leaf and apply to the ulcer. Do not disturb it for 10 min until it dries up.

Green tea with honey

Green tea is a natural antioxidant rich in flavonoids. Honey is a vital ingredient in many Ayurvedic products. Honey has antibacterial properties and can accelerate the healing of ulcers. Daily use of Green tea with honey can be beneficial in treating such ulcers.

Rinse the oral cavity with green tea mixed with honey and warm water. Repeat the same twice daily.

The third method includes preparing a high-concentration extract of green tea. Mix it well with honey and apply it directly onto the ulcer using gauze cotton. keep the cotton intact, on the lesion for 5 minutes, and remove.


Curcumin or turmeric has potent anti-inflammatory, antioxidant, and immunomodulatory properties. Studies by Tim et al. revealed enhanced wound healing of ulcers by topical application of turmeric, in animal studies.

Apply the turmeric paste over the ulcer with a finger and leave the ulcer till it dries.

Sesame oil

Sesame oil is a natural vegetable oil obtained from sesame seeds. It is rich in vitamins and has excellent anti-inflammatory properties. This “Queen of oils” is often used in treating canker sores due to its pain reduction property.

Local application of sesame oil includes placing the oil-containing gauze on the ulcer for 10 minutes.

Salt in water

Mouth gargling of salt in Luke-warm water can be an effective way to treat canker sores. These mouth rinses can increase blood supply to the tissues and prevent bacterial growth hastening the healing process.


Research studies linked the presence of canker sores to gastrointestinal tract diseases like peptic ulcers and Chron’s disease. Few studies marked the association between oral ulcers and H.Pylori bacteria.

Yogurt (an emulsion of fat) can form a protective hydrophobic coat around the ulcer isolating it from surrounding irritants. It can speed up the healing process.

Milk of magnesia

Well known as an oral buffer, milk of magnesia helps neutralize acidic products in the oral cavity. A few drops of it on the ulcer for three times a day (before having food) can be useful in treating ulcers.

Chamomile extract

Chamomile has been used for centuries to treat many oral diseases. Its analgesic effect can help in curing canker sores.

Apply chamomile extract on the ulcer twice daily, leaving it to dry for 10 to 15 min can be sufficient.


Ice has anti-inflammatory properties. A piece of ice on and off the ulcer for 10 min can aid in decreasing the inflammation in canker sores.

Vitamin b complex

Canker sores are more common in patients with vitamin deficiency. The immunity of humans is not stable. It tends to increase and decrease periodically. Patients in a phase of reduced resistance are more prone to have canker sores.

Such conditions are best treated with immune busters like Vitamin B-complex supplements along with zinc.

Popping a canker sore? Never do it

Patients often ask me this question – doctor! Can I pop my ulcer? Popping is a procedure where the lesion is pinched with fingers. It is usually seen in acne or in vesicular eruptions.

Never do the popping. An ulcer is not a blister of a vesicle to pop. Moreover, it may hurt you. Popping often causes a secondary bacterial infection which increases the pain and severity of the lesion.


It is wise to visit your dentist to have a specific treatment for your canker sores.

All ulcers are not canker sores. There are many lesions that mimic them. Hence wiser people should consult a dentist or an oral physician for correct diagnosis and treatment.

Remedies at home can help you to some extent. But without a correct diagnosis, I am afraid there are equal chances of wrong treatment. Hence visit your dentist today.

Download a free ebook on Canker Sores!

Dr. Kiran

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