Clinical Reference / Therapeutic Strategies / Aphthous Ulcers (Recurrent Aphthous Stomatitis, Canker Sore)

Aphthous Ulcers (Recurrent Aphthous Stomatitis, Canker Sore)


First-line therapy: Patients with active ulcers should avoid trauma to the oral mucosa (including hard toothbrushes or sharp foods) and limit intake of acidic products which can worsen pain. Topical analgesics and local protective topical medicaments may provide symptomatic relief. Topical corticosteroids can accelerate healing and improve pain. Antimicrobial rinses may reduce the number of outbreaks and increase disease-free periods between ulcerations. Gel-based topical are the easiest to apply and tend to be better tolerate than other vehicles. Topical medicaments may be compounded in alternative vehicles, such as pastes (Orabase, Iso-Dent) to improve adherence to the moist mucosal surfaces. Amlexanox paste is an anti-inflammatory topical which can improve healing and reduce ulcer size. Major aphthae may require systemic therapy. Most of the therapies discussed herein are not FDA approved for this indication; 1% triamcinolone dental paste is approved for relief of inflammatory conditions in the mouth, and 5% amlexanox paste is approved specifically for aphthous ulcerations.

Recurrent aphthous stomatitis, minor ulcerations

First steps

  • Topical anesthetics (0.15% benzydamine oral rinse, 2-5% lidocaine gel) may be applied to ulcers four times daily for two weeks or until ulcers heal to relieve pain.
  • Protective films, such as carmellose or Orabase, may be applied to the ulcers to diminish discomfort.
  • Topical corticosteroids (1% triamcinolone dental paste, 0.05% fluocinonide in Orabase, 2.5 mg hydrocortisone lozenge, betamethasone aerosol) may be used up to four or five times daily for two weeks or until ulcers resolve to speed healing and decrease pain from ulcers.
  • 5% amlexanox paste may be applied four times daily for two weeks or until ulcers heal.

Ancillary steps

Antimicrobial rinses (chlorhexidine gluconate, triclosan) may decrease bacterial plaques and limit outbreaks in some patients. 0.2% chlorhexidine gluconate mouthwash three times daily or 0.15% triclosan mouthwash twice daily for six weeks can reduce duration of lesions and pain, and lead to fewer outbreaks and fewer total ulcerations. Listerine mouthwash may reduce lesion duration and pain as well.

Subsequent steps

  • Patients may be counseled to avoid foods that may trigger or worsen eruptions, such as nuts, acidic foods or drinks, salty meals, and alcohol. Oral hygiene products containing sodium lauryl sulfate may trigger oral ulcers in some patients as well.
  • Systemic therapy is rarely indicated for minor aphthae of recurrent aphthous stomatitis. If local methods fail, physicians should revisit the differential diagnosis and consider extended workup for mimics of aphthous ulcers. Systemic therapies are discussed below, under major aphthae.
  • In certain cases physicians may opt to order lab tests to evaluate for nutritional deficiencies or rarer underlying causes of oral ulcerations. This may include evaluation of vitamins including iron, ferritin, total iron-binding capacity, folate, vitamin B levels, zinc, and magnesium, and evaluation of a complete blood count. Depending on the patient’s history and review of systems, further testing for systemic diseases may be indicated, which could include antinuclear antibody and antineutrophilic cytoplasmic antibody levels, tissue transglutaminase antibodies, local or serological viral testing, gastroenterological evaluation, and more.

Severe aphthous stomatitis / major aphthae

First steps

Initial management is based on local topical therapies as noted above. Patients with severe recurrent aphthous stomatitis often require systemic therapies to control disease. Oral prednisone (30-60 mg daily) tapered over a two-week course may help heal ulcers more rapidly.

Ancillary steps

Thalidomide 100 mg daily may reduce ulcer outbreak and can offer significant symptomatic relief to patients who suffer from major aphthous ulcers. Thalidomide may be effective even at lower doses. Due to the potential for serious adverse effects (teratogenicity, deep vein thrombosis, and neuropathy), thalidomide use is tightly regulated by the US government (requiring patients and prescribers to be part of the national STEPS registry program).

Subsequent steps

Alternative systemic agents have been used in case reports or small case series. These are generally drugs that target neutrophils (colchicine, dapsone) or TNF (pentoxifylline, infliximab, or etanercept).


  • Using topical steroids for prolonged periods in the mouth can predispose to oral candidiasis. Long-term use of local steroids can lead to systemic absorption when applied to the mucosa, particularly when the surface is ulcerated.
  • Any oral mucosal ulcer which fails to heal after three or four weeks warrants evaluation and possible biopsy to rule out malignancy.
  • Aphthae are diagnosed by history and physical exam alone; there is a broad differential for diseases which can manifest with oral ulcerations, and extended work-up is indicated if there are signs or symptoms of a systemic process.

When to refer to a dermatologist

  • Any ulcer which fails to heal after three or four weeks warrants evaluation and possible biopsy; this may be managed by a dermatologist or an oral medicine physician.
  • Widespread oral erosions, or oral erosions accompanied by cutaneous bullae, should prompt consideration for a mucocutaneous disorder such as pemphigus or a severe drug eruption.
  • If the diagnosis is uncertain or there are systemic symptoms suggestive of a more widespread process, referral to a specialist may be appropriate.