• Aphthous ulcers are painful, clearly defined, round or ovoid, shallow ulcers that are confined to the mouth and are not associated with systemic disease. For further information about diagnosing aphthous ulcers see Diagnosing aphthous ulcers.

• Ask about possible precipitating factors.
• Ask about the frequency and duration of episodes, and the severity of any associated pain.
• Ask about previously tried treatments (either over-the-counter or prescribed medicines).
• Consider alternative diagnoses or an underlying condition if the ulcers first occur later in life (e.g. more than 30 years of age), have lasted for longer than 3 weeks, affect atypical sites in the mouth (e.g. the palate or gums), affect extra-oral sites (e.g. genitalia), or are associated with systemic features (see Differential diagnosis).
• Consider investigations (e.g. full blood count, eosinophil sedimentation rate, ferritin, folate and vitamin B₁₂) to rule out underlying disease if ulceration frequently recurs.

In depth

• Where possible manage precipitating factors:
• Oral trauma: use a softer toothbrush, and avoid hard foods such as toast.
• Anxiety or stress: try relaxation techniques (e.g. yoga, meditation, exercise).
• Certain foods: if there is an obvious relationship to particular foods these are best avoided.
• Stopping smoking: explain that smoking cessation may precipitate ulceration, but that this will settle and the overall health benefits are greater than the short-term discomfort; nicotine replacement therapy may provide some relief.
• Offer symptomatic treatment for pain, discomfort, and swelling. Options include:
• A low-potency topical corticosteroid (e.g. hydrocortisone lozenges). Encourage people with prodromal symptoms, such as tingling or swelling, to apply corticosteroids at this stage. Otherwise, they should be applied as soon as the ulcers appear.
• An antimicrobial mouthwash (e.g. chlorhexidine gluconate).
• A topical analgesic (e.g. benzydamine hydrochloride) if ulcers are very painful.
• If ulcers are infrequent, mild, and not interfering with daily activities (e.g. eating), treatment may not be needed.
• Advise the person to return if there is worsening of, or no improvement in, symptoms with treatment or if the ulcer persists after 3 weeks.

In depth

• Refer urgently anyone with:
• Unexplained ulceration of the oral mucosa or mass persisting for more than 3 weeks.
• Unexplained red and white patches (including suspected lichen planus) of the oral mucosa that are painful, swollen, or bleeding.
• Symptoms or signs related to the oral cavity that persist for more than 6 weeks if a definitive diagnosis of a benign lesion cannot be made.
• Make a non-urgent referral for anyone with:
• Unexplained red and white patches (including suspected lichen planus) of the oral mucosa that are not painful, swollen, or bleeding.
• A suspected underlying cause of aphthous-like ulceration, suggested by history, examination, or results of investigations (see Differential diagnosis).
• Particularly painful and disabling aphthous ulceration or if recurrences are frequent and severe and not adequately relieved by symptomatic treatments.
• Refer to a dentist anyone with a suspected localized dental cause of recurrent ulceration, such as poorly-fitting dentures or a damaged tooth. This may be suggested by recurrent ulceration in the same place.

In depth