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Benzocaine For Canker (Mouth) Sores

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Benzocaine is the ester of cocaine, a popular street drug. However, one need not worry, as due to esterification it does not have any addictive or euphoric properties and this is even sold without prescription. When applied locally as a mouth gel it works almost immediately to relieve pain.

Canker sores, also called aphthous ulcers by doctors, are benign and superficial lesions; they are usually small in size.

They develop on the soft tissues of the mouth, including the inside of cheeks, gums, the lower side of the tongue, but they do not occur on the outer lips.

Canker sores (not to be confused with Cold Sores) are not contagious, however, they are painful in most of the cases. 

They are quite common, and fortunately, in the majority of cases, they will go away without any treatment in a week or two. However, in a small number of instances, recurrent canker sores are common. It is estimated that about 0.1% of the population suffers from frequent canker sores.

Studies show that canker sores are less common among smokers, but more common in those with a low level of insulin.

People living with disease conditions, like an HIV infection, are also more prone to these sores. They are more commonly associated with food allergies, nutritional deficiencies, autoimmune disorders, various systemic diseases, stress, and so on. Other causes could be nutritional deficiencies and hormonal changes.

Not all canker sores are small.

In a small number of cases, they may become large and deep and may even cause permanent scarring on the mucous membrane. Diagnosing them does not pose any difficulty, and most doctors can immediately recognize them.

In most cases, doctors will start anti-inflammatory, and antiseptic mouthwashes like those containing triclosan.

And for pain relief, they will frequently recommend some local anesthetic in the form of a spray, or gel, or even lozenges (like benzocaine lozenges). Severe cases may need immune-modulating therapy or even use of corticosteroids either applied locally or given orally (Altenburg et al., 2014).

Role of Benzocaine in the treatment of canker sores

Benzocaine will not treat canker sores, but it will provide immediate pain relief as it is a local anesthetic. In many cases, it may be the only treatment that may be required as canker sores will get well in most people without any other medication.

Some physicians may also recommend using some mouthwash.

Benzocaine is the ester of cocaine, a popular street drug. However, one needs not to worry, as due to esterification it does not have any addictive or euphoric properties and this is even sold without prescription.

Local anesthetic properties of cocaine were discovered in the 1860s when it was found to cause numbing of the tongue. Later research led to the development of safer anesthetics in the form of esters and amides (Kumar, Chawla, & Goyal, 2015).

When applied locally as a mouth gel it works almost immediately to relieve pain.

It works by blocking the nerve conduction in the region and causing numbness. It acts promptly on the mucosal nerve ending.

Pros of Benzocaine

Unlike products such as Abreva, the most significant benefit of using benzocaine is the immediate effect.

Unlike other pain killers, one does not need to wait. Moreover, it causes complete local numbness, which means that almost a hundred percent pain control. None of the oral medications can act so fast or help with 100% pain relief.

Another benefit is that it works in all the cases, without any exceptions.

It is ideally suited for short-term, and instant pain relief. Since it is applied locally, it also means that systemic side effects are rare. It is very uncommon for anyone to report any side effects, that is why it is commonly added to various over-the-counter remedies.

It is safe even if small amounts go into the stomach (Kumar et al., 2015).

Cons of Benzocaine

There are practically no downsides to using Benzocaine. However, it should be understood that when used to treat canker sores, it only provides pain relief. 

It has no other role in the treatment; it will not shorten the course of the disease.

It means that prolonged use may not be comfortable. Some people do not like the numbing effect of benzocaine as it also alters the sense of taste.

Side effects of Benzocaine

When used topically, side effects are rare and mostly limited to rare allergic reactions. 

However, more severe side effects may occur due to systemic toxicity when the recommended dosage is exceeded.

Systemic side effects at high doses include dizziness, diplopia, tinnitus. It can produce CNS excitement at very high doses like confusion, seizures, or may lead to CNS depression characterized by drowsiness and even coma.

Cardiovascular side effects include hypertension, tachycardia, arrhythmias. Among the rare side effects is methemoglobinemia (Hegedus & Herb, 2005; Kumar et al., 2015).

Contraindications of Benzocaine

Benzocaine is contraindicated to the patient with a proven allergy to it or other ester anesthetics. Those allergic to hair dyes and sulfonamides must also practice caution.

Another critical contraindication is the age below two years, due to the higher risk of methemoglobinemia in the population group. In young children or infants, it can occur in two hours and may be fatal in many cases (Young, 2018).


Canker sores do not pose any severe threat to health; however, they cause severe discomfort. They are characterized by severe pain in many cases.

Moreover, they may occur recurrently in some individuals. Due to poor understanding of their etiology treatment with corticosteroids or other immuno-modifying agents is reserved for severe cases.

For most people, topical treatment with antiseptics will suffice. Whereas, topical application of benzocaine may provide pain relief and improve quality of life. Benzocaine is immediately useful and safe in most individuals.


Altenburg, A., El-Haj, N., Micheli, C., Puttkammer, M., Abdel-Naser, M. B., & Zouboulis, C. C. (2014). The Treatment of Chronic Recurrent Oral Aphthous Ulcers. Deutsches Ärzteblatt International, 111(40), 665–673. https://doi.org/10.3238/arztebl.2014.0665

Barrons, R. W. (2001). Treatment strategies for recurrent oral aphthous ulcers. American Journal of Health-System Pharmacy, 58(1), 41–50. https://doi.org/10.1093/ajhp/58.1.41

Chattopadhyay, A., & Chatterjee, S. (2007). Risk indicators for recurrent aphthous ulcers among adults in the US. Community Dentistry and Oral Epidemiology, 35(2), 152–159. https://doi.org/10.1111/j.1600-0528.2007.00329.x

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