Can Augmentin Cause Mouth Sores? Understanding the Oral Side Effects

October 12, 2025 •

4 min read

Studies show that children taking sugar-sweetened medications have a higher risk of enamel damage [1.2.8]. While not always sugary, the antibiotic Augmentin is also associated with oral issues. So, can Augmentin cause mouth sores and other problems? Yes, it is a recognized, though not universal, side effect [1.2.2].

Quick Summary

Augmentin can lead to mouth sores, oral thrush, and other oral side effects by disrupting the mouth's natural bacterial balance. Management involves good oral hygiene and sometimes medical treatment.

Key Points

Direct Side Effect: Mouth sores are a recognized, though less common, side effect of taking Augmentin [1.2.2, 1.2.3].
Oral Thrush Link: Augmentin can disrupt the mouth's natural bacteria, leading to a fungal overgrowth called oral thrush, which also causes mouth soreness [1.4.1, 1.4.2].
Allergic Reactions: Sores in the mouth can be a symptom of a mild or serious allergic reaction to the medication, sometimes involving swelling of the lips or tongue [1.2.7].
Rare Severe Reactions: In very rare instances, mouth sores can be an early sign of a life-threatening condition like Stevens-Johnson syndrome (SJS), which requires immediate medical attention [1.3.1, 1.5.4].
Other Oral Effects: Besides sores, Augmentin may also cause temporary tooth discoloration (especially in children) or a benign condition called 'black hairy tongue' [1.3.1, 1.7.1].
Management is Key: Home care, such as saltwater rinses and avoiding spicy foods, can manage mild sores. Do not stop the antibiotic without medical advice [1.6.2, 1.4.4].
Consult a Doctor: Seek medical help for severe symptoms, signs of an allergic reaction, or if sores persist, as you may need different treatment [1.3.1, 1.4.3].

Understanding Augmentin and Its Function

Augmentin is a popular combination antibiotic containing amoxicillin and clavulanic acid. The amoxicillin component is a penicillin-type antibiotic that fights bacteria, while clavulanic acid is a beta-lactamase inhibitor [1.7.1]. Its purpose is to overcome resistance from bacteria that produce beta-lactamase, an enzyme that can destroy amoxicillin, making the antibiotic effective against a wider range of bacterial infections [1.5.2]. It is commonly prescribed for infections of the sinuses, ears, lungs, skin, and urinary tract [1.4.4, 1.7.1]. While highly effective, like all medications, it carries a risk of side effects, including several that affect the mouth.

Can Augmentin Cause Mouth Sores and Ulcers?

Yes, mouth sores and ulcers are a recognized side effect of taking Augmentin [1.2.2, 1.2.3]. While common side effects are typically gastrointestinal, like diarrhea and nausea, oral issues can also occur [1.3.5]. These sores can appear as redness, blistering, or peeling skin inside the mouth [1.2.4].

There are a few reasons why this happens:

Disruption of Oral Microbiome: Antibiotics like Augmentin don't just target harmful bacteria; they can also disrupt the normal, healthy balance of microorganisms in your mouth [1.4.2]. This can allow for the overgrowth of other organisms, leading to irritation and sores.
Allergic Reactions: For some individuals, mouth sores can be part of a mild or severe allergic reaction. Symptoms might include swelling of the lips, tongue, or throat, alongside a rash or itching [1.2.6, 1.2.7].
Severe Skin Reactions: In very rare cases, Augmentin can trigger severe and life-threatening skin reactions like Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) [1.3.3, 1.5.4]. These conditions often begin with flu-like symptoms, followed by a painful rash and the development of blisters and sores on mucous membranes, including the mouth, nose, and genitals [1.2.5, 1.5.4]. This is a medical emergency requiring immediate attention [1.5.4].

Other Oral Side Effects of Augmentin

Besides mouth ulcers, Augmentin can cause other oral health issues:

Oral Thrush (Candidiasis): This is a fungal infection caused by an overgrowth of the yeast Candida [1.4.1]. Antibiotics can kill the bacteria that normally keep Candida in check, allowing it to multiply [1.4.2]. Symptoms include white patches on the tongue and inner cheeks, soreness, and a cottony feeling in the mouth [1.2.8].
Black Hairy Tongue: This benign condition is characterized by a dark, furry appearance on the surface of the tongue [1.7.1]. It's caused by a buildup of dead skin cells on the papillae (the tiny bumps on the tongue), which then become stained by bacteria, yeast, or other substances [1.7.7]. Several antibiotics, including amoxicillin-clavulanate, have been linked to this condition [1.7.1, 1.7.2].
Tooth Discoloration: A change in tooth color to yellow, gray, or brown has been reported, particularly in children [1.3.1, 1.4.1]. In most cases, this discoloration can be reduced or removed with regular brushing or a professional dental cleaning [1.3.1, 1.4.1].


Side Effect	Primary Cause	Common Symptoms	Severity
Mouth Sores/Ulcers	Direct irritation, allergic reaction [1.2.2, 1.2.7]	Painful red spots or open sores inside the mouth [1.2.4].	Mild to Severe
Oral Thrush	Fungal (Candida) overgrowth after bacterial disruption [1.4.2]	White patches, soreness, cottony feeling [1.2.8].	Mild to Moderate
Black Hairy Tongue	Defective shedding of papillae, bacterial/yeast growth [1.7.7]	Dark, furry-looking discoloration of the tongue [1.7.1].	Mild (cosmetic)
Tooth Discoloration	Medication deposit	Yellow, gray, or brown staining of teeth [1.3.1].	Mild (often reversible)
Stevens-Johnson Syndrome (SJS)	Severe immune reaction [1.5.5]	Blisters and sores on skin and mucous membranes (mouth, eyes, genitals) [1.2.1, 1.2.5].	Severe / Life-Threatening

Managing Mouth Sores from Augmentin

If you develop mouth sores while taking Augmentin, several strategies can help provide relief. It is crucial not to stop taking your antibiotic without consulting your doctor [1.4.4].

Home Care and Symptomatic Relief

Practice Good Oral Hygiene: Gently brush your teeth with a soft-bristle toothbrush and floss daily to keep the area clean [1.6.2, 1.6.7].
Saltwater Rinse: Gargling with a warm saltwater solution a few times a day can help clean the sores and promote healing [1.6.2]. A baking soda rinse can also be effective [1.6.4].
Avoid Irritants: Stay away from hot, spicy, salty, or acidic foods and beverages that can aggravate the sores [1.6.2, 1.6.4]. Drink cool drinks, possibly through a straw [1.6.7].
Over-the-Counter (OTC) Products: Topical anesthetic gels like Orajel™ or Anbesol® can provide temporary pain relief [1.6.2]. Protective pastes can also cover the sore [1.6.4].

When to See a Doctor

You should contact your healthcare provider right away if you experience any of the following:

Signs of a severe allergic reaction, such as swelling of the face, lips, or throat, or difficulty breathing [1.3.1].
A widespread rash, blisters, or peeling skin, especially if accompanied by fever or sores in the eyes, nose, or genital area, as these could be signs of SJS/TEN [1.3.1, 1.3.4].
Sores that are very large, numerous, or last longer than two weeks [1.6.4].
Symptoms of oral thrush (white patches) [1.4.3]. Your doctor may need to prescribe an antifungal medication [1.2.8].

Conclusion

While an effective antibiotic, Augmentin can indeed cause mouth sores and other oral side effects like oral thrush and black hairy tongue [1.2.2, 1.4.1, 1.7.1]. These issues often stem from the drug's disruption of the mouth's natural microbiome or, more rarely, an allergic reaction [1.2.7, 1.4.2]. Most oral side effects are mild and manageable with good oral hygiene and by avoiding irritants [1.6.7]. However, it is essential to monitor for signs of a severe reaction, such as Stevens-Johnson syndrome, and to consult a doctor for persistent or severe symptoms [1.3.1].

For more information, you can visit MedlinePlus [1.3.2].

Frequently Asked Questions

Mouth sores or other reactions can develop within a few days of starting the medication. For rare, severe reactions like SJS, the onset can be from 1 to 38 days after the first dose [1.5.2].

Oral thrush is generally not contagious in healthy individuals. It's caused by an overgrowth of yeast that is already present in the mouth [1.2.8, 1.4.2].

You should not stop taking Augmentin without first consulting your doctor. They can determine the cause of the sores and advise the best course of action [1.4.4].

Yes, children can experience oral side effects. Tooth discoloration has been reported most often in children, and they can also develop mouth sores or severe skin reactions [1.3.1, 1.5.1].

Black hairy tongue is a harmless, temporary condition where the tongue appears dark and furry. It's caused by an overgrowth of the tiny bumps (papillae) on the tongue, which can be triggered by antibiotics like Augmentin [1.7.1, 1.7.7].

While not always preventable, maintaining excellent oral hygiene, staying hydrated, and rinsing your mouth after taking liquid medication can help reduce the risk. Rinsing with salt water can also be a helpful preventative measure [1.6.2, 1.6.7].

Usually, they are a mild side effect. However, if accompanied by a widespread rash, blisters, fever, or swelling, they can be a sign of a severe and dangerous reaction like Stevens-Johnson syndrome (SJS) and require immediate medical evaluation [1.3.1, 1.5.4].