Do Ulcers Get Bigger Before Healing? A Look at the Healing Process

September 27, 2025 •

4 min read

According to the National Institutes of Health, minor mouth ulcers typically heal within one to two weeks, but not all ulcers follow the same path. A common point of confusion for many is whether ulcers get bigger before healing, and the answer depends on the type of ulcer and its stage of development.

Quick Summary

Yes, some types of ulcers, particularly canker sores and traumatic mouth ulcers, do tend to enlarge before they stabilize and begin to shrink, which can cause concern for those unfamiliar with the healing process. This initial growth phase is a normal part of the ulcer's development before it enters the repair stage.

Key Points

Initial Growth is Normal: For many ulcers, especially canker sores, an initial period of enlargement and inflammation is a normal stage before healing begins.
Inflammatory Phase: The ulcer may appear to grow in the first few days as the body's inflammatory response creates a fully-formed lesion.
Peak Pain and Size: The ulcer often reaches its maximum size and pain level during the ulceration stage, before the repair phase starts.
Healing Starts After Stabilization: True healing, where the ulcer shrinks, occurs after it has stabilized and is no longer actively expanding.
Monitor Persistence: While initial growth is normal, an ulcer that continues to grow or does not show signs of healing within a few weeks requires medical evaluation.

Understanding the Ulcer Healing Timeline

The healing process for an ulcer is not a simple, linear progression. It involves several stages, and in many cases, an initial period of enlargement is a normal part of the process before the tissue starts to repair itself. This is particularly true for mouth ulcers, such as canker sores or traumatic ulcers, but can also be relevant for other types of ulcers.

The Initial Stage: Inflammation and Formation

When a canker sore first develops, it begins with a tingling or burning sensation. Over the next few days, the area becomes red and slightly swollen. This is the body's inflammatory response kicking in. The ulcer itself then forms, often growing to its final size within 3-4 days. During this time, it is common for the ulcer to appear to get bigger as the inflammatory response progresses and the full wound is established.

The Stabilization and Repair Phase

Following the initial enlargement, the ulcer stabilizes. This is when the ulcer is typically at its most painful and is fully formed, often with a whitish or yellowish center and a red border. The body then begins the true healing process, where new tissue is formed to close the wound. This phase can take varying amounts of time depending on the size and type of the ulcer.

Factors Influencing Ulcer Healing

The speed and nature of ulcer healing are influenced by several factors. Understanding these can help manage expectations and care for the ulcer properly.

Type of Ulcer: Different ulcers have different healing times. Minor aphthous ulcers (the most common type of canker sore) heal relatively quickly, while major aphthous ulcers can take weeks or even months and may leave a scar.
Size and Location: Larger ulcers generally take longer to heal. The location also matters; ulcers in areas of constant friction, like the inside of the cheek, may heal more slowly.
Individual Health: A person's overall health, nutritional status, and immune system function can significantly affect the healing process. Poor nutrition or a compromised immune system can slow down recovery.
Irritation: Continuous irritation from spicy food, acidic drinks, or sharp teeth can delay healing and potentially cause the ulcer to appear larger or more inflamed for a longer period.

A Comparison of Ulcer Types and Healing

To better understand the process, here is a comparison of different common ulcer types.


Feature	Minor Aphthous Ulcer (Canker Sore)	Major Aphthous Ulcer	Traumatic Ulcer (Mouth)
Initial Growth	Yes, enlarges to final size over a few days.	Yes, can get quite large before stabilizing.	Yes, starts small and enlarges into a crater.
Maximum Size	Typically under 1 cm in diameter.	Over 1 cm, can be quite large.	Varies depending on trauma.
Typical Healing Time	1-2 weeks.	Several weeks to months.	Up to 2 weeks.
Pain Level	Moderate, peaks during ulceration phase.	Severe, can interfere with eating/drinking.	Varies, can be significant due to irritation.
Scarring	Rare.	Can leave a scar.	Unlikely unless severe trauma.

What to Do When an Ulcer Forms

If you have a mouth ulcer, there are several steps you can take to manage it and promote healing.

Practice good oral hygiene: Gently brush your teeth and use a soft-bristled toothbrush to avoid further irritation.
Avoid trigger foods: Steer clear of spicy, acidic, or very hot foods and beverages that can worsen the pain and irritate the ulcer.
Use over-the-counter remedies: Mouthwashes specifically for ulcers or topical anesthetics can provide temporary relief from pain.
Consider topical treatments: Some gels or pastes can create a protective barrier over the ulcer, helping to shield it from irritation.
Maintain good nutrition: A balanced diet rich in vitamins and minerals, especially B vitamins and iron, can support the body's natural healing processes.

When to Seek Medical Attention

While most ulcers heal on their own, certain signs indicate it's time to see a doctor.

An ulcer that is unusually large or painful.
An ulcer that lasts for more than three weeks.
Ulcers that recur frequently.
If you also experience fever, skin rashes, or digestive issues.

It is always wise to consult a healthcare professional for persistent or severe symptoms. For information on specific treatments, please refer to authoritative sources such as the NIH website.

Conclusion

In short, the observation that an ulcer gets bigger before healing can be a completely normal part of its development, particularly for mouth ulcers. This initial growth phase is the body's inflammatory response at work. After this point, the ulcer should stabilize and then begin to shrink as the repair process takes over. However, paying attention to the type of ulcer and its characteristics is key. Knowing the typical timeline for an ulcer, and when to seek professional help, can alleviate anxiety and ensure proper care.

Frequently Asked Questions

An ulcer might get bigger before healing due to the body's inflammatory response. During the initial formation stage, the immune system causes swelling and tissue breakdown, which can lead to an increase in the ulcer's size before it stabilizes and begins to regenerate.

Yes, it is often normal for a mouth ulcer, such as a canker sore, to increase in size during the first 3 to 4 days after it appears. This is part of the natural process before the healing phase starts.

A healing ulcer will typically stop growing, become less painful, and the white or yellowish center will begin to fade. If an ulcer continues to grow significantly after the first few days, becomes increasingly painful, or lasts for more than a few weeks, it may be getting worse and should be checked by a doctor.

While stress doesn't directly cause an ulcer to get bigger, it can weaken the immune system and increase inflammation, which may prolong the inflammatory phase and potentially delay healing, making the ulcer appear more prominent for a longer period.