5 Potential Causes of Multiple Canker Sores at Once

Multiple canker sores at once
Canker sores are the most common mouth ulcerative condition. They affect people differently. For some, it's an occasional annoyance, a single sore at a time that disappears within a week. But for others, it's a more challenging battle, with multiple ulcers at once and frequent outbreaks that persist longer.

While they usually vanish on their own in a matter of days, if they become frequent visitors or take longer to heal, it's time to dig deeper and find out the potential reasons.

In this article, we will explore five potential causes of multiple canker sores at once and how to overcome them.
The different conditions that can lead to canker sores

Here are 5 reasons why you might be getting multiple ulcers. Understanding them will help you manage and prevent them more effectively.

1. Aphthous Stomatitis: The Most Likely Reason

In most cases, mouth ulcers refer to a condition called Aphthous Stomatitis , or as you probably know them, canker sores.

It's an oral inflammatory condition that causes those small, round, or oval sores covered in a white or yellowish layer and surrounded by a red border. These sores are well-known for hurting a lot and can make your life a bit uncomfortable.

They can pop up anywhere in the mouth, from the tongue to the inside of the cheeks and lips.

Can Aphthous Stomatitis Show Up as Multiple Ulcers?

Canker sores can come in different sizes, numbers, and shapes. There are three types – minor, major, and herpetiform.

The minor ones are the most common, usually showing up as one to five small sores at a time. They're the least serious and usually heal within a week or so without leaving any scars.

On the other hand, herpetiform sores can be quite numerous, even up to a hundred separate sores. The term "herpetiform" got its name from oral herpes, a mouth viral infection that can bring about similar symptoms. Sometimes, these multiple ulcers can merge into one large canker sore. These take longer to heal, sometimes lingering for weeks to months.

The major canker sores are the most severe. The good news is that they are less common, accounting only for 10% of cases. These ulcers typically appear as a single, larger, deeper, and extremely painful lesion. They can measure up to several centimeters in size and take longer to heal.

Who Is Most at Risk?

Almost everyone can get canker sores at some point in their life. But, women, nonsmokers, and those with a higher socioeconomic status seem to be more vulnerable (2).

The exact cause is not yet fully understood, but some suspects include genetics, stress, a heightened response to mouth injuries, nutritional deficiencies, and allergies.

If it's your first experience with canker sores, count yourself fortunate. Some people have to deal with them several times a year. We call this Recurrent Aphthous Stomatitis, affecting roughly a quarter of the world's population (3).


Unfortunately, there's no magic cure for canker sores. The good news is they tend to heal on their own. However, there are some things you can do to ease the pain and speed up the healing process.

To alleviate inflammation and discomfort, begin by combining a tablespoon of salt and baking soda with half a glass of water. Gargle with this mixture and repeat several times a day. These two natural ingredients are both soothing and anti-inflammatory, making them your go-to remedy for overcoming canker sores.

You can also apply an over-the-counter numbing product like Orajel or Canker-X Mouth Sore Gel. These contain ingredients that help numb the area, making you feel more comfortable.

Another option is using an antiseptic mouthwash. Look for alcohol-free and peroxide-based options like Orajel Mouth Sore Rinse and Colgate Peroxyl Mouth Rinse. These can help prevent infections and promote healing.

2. Ulcerations Due to Injury or Trauma

The ulcers that pop up after some mouth trauma are different from the typical canker sores. Here, the cause is clear – injury or damage to the mouth's lining by something external.

It could be due to things like an ill-fitting denture, braces, aggressive toothbrushing, consuming too-hot-and-spicy foods or drinks, or going overboard with a harsh alcohol-based mouthwash.

So, if you've been rough on your mouth lately, that might be why you've developed these sores.

Treatment for Traumatic Ulcers

The good news is that traumatic ulcers, like canker sores, usually heal on their own once you remove the source of the injury or trauma.

So, step one is to identify what's causing the problem and address it.

If those sores are painful and making eating difficult, the home remedies and numbing gels we discussed earlier are still effective.

3. Oral Herpes Infection: When the Virus Wakes up Again

Oral herpes is caused by a virus called herpes simplex virus type 1 (HSV-1). Typically, the first encounter with this virus happens during childhood, usually between the ages of 3 to 5. We call this the primary HSV infection.

This primary infection can bring tiny, fluid-filled blisters all over the mouth. These lesions eventually break open to form painful ulcers.

After that initial episode, the virus retreats and hides in the body. In fact, around 67% of people under 50 years old have HSV-1, but most don't even know it because the infection remains silent and asymptomatic (4).

Oral Herpes and Cold Sores

Now, the dormant virus can wake up at any time during adulthood. When it does, it causes lesions, popularly known as fever blisters or cold sores.

The factors that cause the virus to reactivate and produce symptoms again include emotional stress, injury, sun exposure, or a weakened immune system.

The cold sores often target the lower lip but can also appear on the gums or the roof of the mouth.

The outbreak usually starts with a numbing or burning sensation, followed by clusters of blisters in that area. These blisters soon break open, forming multiple painful ulcers.

Oral Herpes Treatment

Cold sores typically heal on their own within 7 to 10 days. However, your dentist might prescribe antiviral medications to help suppress the virus and speed up recovery.

Home remedies and antiseptic mouthwashes can help to find relief and keep those sores from getting infected.

4. Underlying Inflammatory Diseases

Mouth ulcers are essentially intense inflammatory reactions that start in a specific spot and lead to the breakdown of the mouth's lining skin (mucosa).

Similar lesions can be triggered in the mouth by other inflammatory conditions. Two notable examples are Behcet's and Crohn's diseases.

Behcet's Disease

Behcet's disease is a rare disorder that causes chronic inflammation of blood vessels. In your mouth, it can manifest as multiple, superficial, and painful ulcers that resemble canker sores. This disease can also affect other body parts, such as the eyes, skin, kidneys, and brain. While the exact cause remains a bit of a mystery, it's thought to result from abnormal immune activity where the body mistakenly attacks its own cells.

Crohn's Disease

Crohn's disease is another inflammatory condition, primarily affecting the digestive tract. Your mouth is the first part of the digestive system, and it can also become a site of inflammation in this disease. Symptoms might include redness and swelling, especially in your tongue and lips, along with canker sores. In fact, up to 20-30% of patients with Crohn's disease have reported experiencing aphthous ulcers (8).

5. Autoimmune Diseases

In some rare instances, outbreaks of mouth ulcers can be linked to autoimmune diseases such as pemphigus and mucous membrane pemphigoid.

Pemphigus Disease

In pemphigus disease, the immune system overreacts and targets the components of the mouth's lining, specifically the proteins that hold the cells together. This self-destruction process causes fluid to leak through the mucosa, forming fluid-filled, bubble-like lesions. Since these bubbles are delicate, they rupture quickly, leaving behind erosive surfaces and extremely painful ulcers.

Pemphigoid Disease

Pemphigoid follows a similar process, but it affects deeper layers of the oral mucosa, causing blister-like lesions that are tougher and less likely to rupture easily.
These autoimmune diseases don't just stop at the mouth – they can affect other parts of the body as well, including the skin, throat, eyes, and genitals.

Once diagnosed, it's crucial to manage them promptly, as they can be life-threatening. The treatment of choice typically involves oral corticosteroids. These medications work by promoting an anti-inflammatory response and slowing down the immune system to safeguard the body's tissues from additional harm.

Overcoming Multiple Canker Sores

Now that we've explored the various potential causes of having multiple canker sores at once, it's up to you to identify your own risk factors that might be triggering this issue.

By identifying these factors, you can better manage them and take steps to prevent future outbreaks. Consider addressing suspected triggers, such as finding ways to manage stress, avoiding foods that you might be sensitive to, addressing nutritional deficiencies (especially in B12, iron, and zinc), and taking precautions to prevent mouth injuries.

If you find yourself dealing with canker sores that come back multiple times a year, you're not alone. Approximately 25% of the population faces this issue. However, with the right practices, you can overcome them and reduce their severity.

As we've seen, certain underlying diseases can present themselves in the form of mouth inflammation and multiple painful sores. They can range from viral infections and inflammatory conditions to skin disorders. So treating them is essential, both for your oral health and general well-being.