Can diclofenac cause mouth sores?

October 9, 2025 •

4 min read

Diclofenac, a common nonsteroidal anti-inflammatory drug (NSAID), can cause oral health issues, including sores, ulcers, or white spots in the mouth. While gastrointestinal (GI) side effects like stomach ulcers are more widely known, the potential for oral ulceration is an adverse effect that also demands attention.

Quick Summary

Diclofenac and other NSAIDs can cause mouth sores, ranging from mild ulcers to severe reactions like Stevens-Johnson Syndrome. This is linked to the drug's systemic effects on the GI tract and mucosal lining.

Key Points

Oral Ulcers are a Known Side Effect: Diclofenac has been officially reported to cause sores, ulcers, or white spots in the mouth.
Systemic and Local Mechanisms: The sores can result from both the drug's systemic inhibition of protective prostaglandins and local irritation.
Potential for Severe Reactions: In rare but serious cases, mouth sores can be part of a severe allergic reaction like Stevens-Johnson syndrome.
Risk Increases with Dosage and Duration: The likelihood of developing oral ulcers is higher with long-term use and at higher doses of diclofenac.
Consult a Doctor for Management: If you develop mouth sores while on diclofenac, inform your doctor, as discontinuing the drug or adjusting the dose may be necessary.
Home Care Can Provide Relief: Avoiding irritating foods, using saltwater rinses, and practicing good oral hygiene can help manage the symptoms.

The link between diclofenac and mouth sores

Diclofenac, a nonsteroidal anti-inflammatory drug (NSAID), is commonly prescribed for pain and inflammation associated with conditions like arthritis. While its primary targets are enzymes involved in inflammation (cyclooxygenase or COX enzymes), its effects are not confined to the intended areas. Numerous reports and official medication information confirm that oral diclofenac can lead to painful sores, ulcers, or white spots on the lips and inside the mouth. These issues can also manifest as stomatitis, which is general inflammation of the oral mucosa.

How diclofenac can cause oral issues

The development of mouth sores from diclofenac can be attributed to several pharmacological mechanisms and adverse reactions:

Prostaglandin Inhibition: Diclofenac inhibits COX enzymes, which reduces the production of prostaglandins. While this effectively reduces inflammation and pain, some prostaglandins play a protective role in the gastrointestinal and oral mucosal linings. A reduction in these protective substances can leave the mouth and GI tract vulnerable to damage, leading to ulcer formation.
Impaired Mucosal Repair: Studies on NSAIDs have shown they can interfere with the healing process of soft oral tissues. By triggering biochemical changes, NSAIDs can impair the repair mechanisms of the buccal mucosa, amplifying factors that delay the natural healing of ulcers.
Direct Irritation: While less common, improper use of medications, such as holding or sucking on a tablet instead of swallowing it, can cause direct, localized irritation and ulceration of the oral mucosa.
Immune Reactions: In some cases, oral ulcers and lesions can be part of a broader, immune-mediated reaction. Diclofenac has been linked to drug-induced lichenoid eruptions, which present as white, lace-like patterns or painful ulcers. More seriously, it can trigger severe cutaneous adverse reactions like Stevens-Johnson syndrome (SJS), where painful blisters and sores can appear on the skin and mucous membranes, including the mouth.

Risk factors for developing oral ulcers

Several factors can increase a person's risk of experiencing oral adverse effects from diclofenac:

Dosage and Duration: Taking higher doses of diclofenac or using the medication for a prolonged period increases the risk of side effects, including digestive and oral issues.
Pre-existing Conditions: Individuals with a history of stomach ulcers, gastrointestinal bleeding, or other digestive problems are at a higher risk of developing ulcers from NSAIDs.
Combined Medications: The concomitant use of other medications, such as blood thinners or corticosteroids, can heighten the risk of bleeding and ulceration.
Age and Lifestyle: Older patients, individuals who smoke, and those who consume more than three alcoholic beverages per day face a higher risk of serious GI and oral issues.

What to do if you experience mouth sores

If you suspect diclofenac is causing your mouth sores, it is crucial to consult your doctor. Here are some immediate steps and potential treatments:

Discontinuation or Dosage Adjustment: A healthcare professional may recommend stopping the medication or adjusting the dosage. In many cases, drug-induced oral ulcerations improve within a couple of weeks after the drug is discontinued.
Home Care: To manage discomfort, avoid hot, spicy, acidic, or salty foods. Gargling with salt water or a baking soda and water paste can provide relief.
Topical Treatments: Over-the-counter topical anesthetics like gels or mouth rinses may numb the area and provide temporary relief. For more severe cases, prescription steroid gels or mouthwashes might be necessary.
Hydration and Oral Hygiene: Drinking plenty of water and maintaining excellent oral hygiene with a soft toothbrush can help prevent infection and promote healing.

Diclofenac vs. other NSAIDs: A comparison

Oral side effects are not exclusive to diclofenac but are a potential risk with many NSAIDs. Here is a comparison of common oral and GI adverse effects:


Feature	Diclofenac	Ibuprofen	Naproxen
Oral Side Effects	Possible, reported sores and ulcers. May induce lichenoid reactions.	Possible, can cause oral ulcers. Impairs oral mucosal repair.	Possible, can cause oral ulcers. Side effects may include GI issues.
GI Side Effects (Ulcers/Bleeding)	Known risk, especially higher doses/long-term use. Boxed warning for GI bleeding.	Known risk, can cause stomach irritation and ulcers.	Known risk, includes stomach irritation, ulcers, and bleeding. Boxed warning for GI bleeding.
Risk with Dosage	Risk increases with higher doses.	Risk increases with higher doses.	Risk increases with higher doses.
Risk with Duration	Risk increases with longer use.	Risk increases with longer use.	Risk increases with longer use.

Conclusion

Yes, diclofenac can cause mouth sores, ranging from mild oral ulcers and stomatitis to more severe conditions like drug-induced lichenoid reactions or Stevens-Johnson syndrome. This side effect is linked to the drug's anti-inflammatory mechanism, which can compromise the protective lining of the mouth and digestive tract. Risk factors include higher doses, longer duration of use, and pre-existing GI issues. If you develop mouth sores while taking diclofenac, it's essential to inform your doctor to determine if the medication is the cause and to manage the symptoms appropriately. Management may involve adjusting the medication, practicing careful oral hygiene, and using topical treatments to relieve discomfort. For comprehensive information on medication side effects, you can consult resources like the FDA website.

Frequently Asked Questions

While less frequent than digestive issues, mouth sores are a reported side effect of diclofenac. The incidence is not precisely known, but it is documented in medication information.

If the sores are caused by diclofenac, they will typically resolve within one to two weeks after the medication is discontinued, provided no other contributing factors are involved.

Oral forms of diclofenac are more likely to cause systemic side effects, including mouth sores. However, severe skin and mucous membrane reactions like Stevens-Johnson syndrome, which includes mouth sores, can be a potential risk with both oral and systemic use.

An oral ulcer is a painful sore, while a lichenoid drug reaction is an immune-mediated inflammatory response that presents as white, lace-like patterns or erosions, potentially leading to ulcers.

You should contact your doctor if you develop persistent mouth sores, especially if they are large, very painful, or accompanied by a fever, rash, or flu-like symptoms. These could indicate a more severe reaction like SJS.

Yes, factors like higher doses, long-term use, older age, history of stomach ulcers or bleeding, and taking other specific medications can increase the risk of developing oral adverse effects.

While prevention is not guaranteed, taking the lowest effective dose for the shortest duration and avoiding alcohol can help. If you have risk factors, your doctor may monitor you more closely or prescribe a protective medication.