Understanding Mouth Ulcers and Treatment Gels
Mouth ulcers, also known as canker sores or aphthous ulcers, are painful sores that appear inside the mouth [1.2.1]. While most are harmless and heal on their own within one to two weeks, they can cause significant discomfort, making it difficult to eat, drink, and speak [1.2.7, 1.7.4]. These ulcers are not contagious [1.7.5]. Their exact cause is often unknown, but triggers can include minor mouth injuries, stress, hormonal changes, and certain food sensitivities [1.7.4]. Approximately 20% of Americans have experienced a canker sore at least once [1.2.5].
To manage the pain, many people turn to over-the-counter (OTC) mouth ulcer gels. These products are designed to provide temporary relief by numbing the area or reducing inflammation. They typically contain one or more active ingredients that work in different ways to alleviate symptoms. However, it's crucial to be aware of their potential side effects.
Common Active Ingredients and Their Function
Most OTC mouth ulcer gels rely on a few key active ingredients:
- Local Anesthetics (e.g., Benzocaine, Lidocaine): These agents work by blocking nerve signals in the affected area, which numbs the pain [1.4.7, 1.3.7]. Benzocaine is a very common ingredient in products like Orajel and Anbesol [1.3.2, 1.6.6]. Lidocaine serves a similar purpose, decreasing the sensation of pain by stopping pain signals from the nerves to the brain [1.3.7].
- Anti-inflammatory Agents (e.g., Choline Salicylate): This ingredient is a non-steroidal anti-inflammatory drug (NSAID) [1.5.4]. It works by blocking the production of chemical messengers called prostaglandins, which are responsible for pain and inflammation (redness and swelling) [1.3.7, 1.5.4].
- Antiseptics (e.g., Benzalkonium Chloride, Chlorhexidine Gluconate): These components help to kill bacteria in and around the ulcer, which can prevent secondary infections and aid in the healing process [1.3.3, 1.6.4].
- Astringents (e.g., Tannic Acid): These substances can help to dry out the ulcer and form a protective layer over it.
Common and Mild Side Effects
For most users, the side effects of mouth ulcer gel are minor, localized to the application area, and temporary. They often resolve as the body adjusts to the medication [1.3.7].
Commonly reported side effects include:
- A temporary burning or stinging sensation upon application [1.3.2, 1.3.5, 1.3.7].
- Mild itching, redness, or irritation at the site [1.3.2, 1.5.3].
- Temporary numbness of the tongue or surrounding mouth area [1.3.3, 1.3.5].
- A bitter or unpleasant taste in the mouth [1.5.2].
- Dryness of the oral mucosa [1.5.2].
Because these gels can cause numbness, there is an increased risk of accidentally biting your tongue or cheek. It is often advised to avoid eating or chewing gum while the area is numb [1.3.2, 1.3.3].
Serious Side Effects and When to Be Concerned
While rare, some ingredients in mouth ulcer gels can cause serious adverse reactions. It is vital to recognize these symptoms and seek immediate medical attention if they occur.
Methemoglobinemia (Associated with Benzocaine): This is a rare but life-threatening condition where the amount of oxygen carried in the blood is greatly reduced [1.4.2, 1.4.4]. The FDA has issued warnings that OTC oral drug products containing benzocaine should not be used for infants and children under 2 years old due to this risk [1.4.4]. Symptoms can appear within minutes to a couple of hours after use and require immediate medical help [1.4.2, 1.4.5].
Symptoms of Methemoglobinemia include:
- Pale, gray, or blue-colored skin, lips, and nail beds [1.4.2, 1.4.5].
- Shortness of breath [1.4.2].
- Headache and lightheadedness [1.4.2].
- Rapid heart rate [1.4.2].
- Fatigue and confusion [1.4.2].
Allergic Reactions: A severe allergic reaction to any ingredient in the gel is possible. Symptoms can include:
- Skin rash, hives, or itching [1.3.2, 1.3.4].
- Swelling of the face, lips, tongue, or throat [1.3.2].
- Difficulty breathing or wheezing [1.3.2].
- Trouble swallowing [1.3.2].
- Dizziness or fainting [1.3.2].
Salicylate-Related Issues (from Choline Salicylate): As a salicylate, similar to aspirin, choline salicylate carries risks, especially with excessive or prolonged use. Though rare with topical application, systemic absorption can occur [1.5.6]. It can cause stomach upset or, in very rare cases, contribute to bleeding or stomach ulcers [1.5.1, 1.5.6]. People with an allergy to aspirin or other NSAIDs should avoid products with choline salicylate [1.5.2].
Comparison of Common Active Ingredients
| Active Ingredient | Primary Function | Common Side Effects | Serious Risks |
|---|---|---|---|
| Benzocaine | Local Anesthetic | Stinging, burning, temporary numbness [1.3.2] | Methemoglobinemia, severe allergic reactions [1.4.2, 1.3.2]. Not for children under 2 [1.4.4]. |
| Lidocaine | Local Anesthetic | Stinging, burning, numbness [1.3.3, 1.3.7] | Allergic reactions, blocking of pain signals leading to injury (e.g., biting) [1.3.7, 1.3.3]. |
| Choline Salicylate | Anti-inflammatory | Burning sensation, irritation, taste changes [1.5.3, 1.5.4] | Stomach upset, potential for bleeding/ulcers with overuse, Reye's syndrome risk in children [1.5.1, 1.5.6]. |
| Benzalkonium Chloride | Antiseptic | Mild irritation [1.3.3] | Primarily a risk if swallowed; generally considered safe for topical oral use [1.3.3]. |
When to See a Doctor
You should stop using mouth ulcer gel and consult a doctor or dentist if:
- You experience any symptoms of a serious side effect like methemoglobinemia or a severe allergic reaction [1.3.2, 1.4.2].
- The mouth ulcer lasts for more than two or three weeks [1.7.1, 1.7.3].
- The sores are unusually large, recurring frequently, or spreading [1.7.3, 1.7.6].
- The pain is severe and not controlled by OTC measures [1.7.3].
- You develop a high fever, rash, or feel generally unwell along with the ulcer [1.7.1, 1.7.3].
Conclusion
Mouth ulcer gels are an effective tool for managing the pain of canker sores for many people. The most common side effects are mild and localized, such as temporary stinging or numbness. However, users must be aware of the active ingredients in their chosen product. Gels containing benzocaine carry a rare but serious risk of methemoglobinemia, and the FDA advises against their use in children under two [1.4.4]. Always use the product as directed, be aware of the signs of serious side effects, and consult a healthcare professional if your mouth ulcer persists or is accompanied by other concerning symptoms [1.7.3].
For more information on oral health, you can visit the American Dental Association.
