Typically acquired by direct sexual contact with the infectious lesions of another person
Results in painless indurated ulcer at site of entry of bacterium Treponema pallidum
Most common site is genital, but oral and pharyngeal lesions can be the site of entry
Left undiagnosed and untreated can progress to secondary and tertiary syphilis
Mucosal leishmaniasis
Involvement of mucosal tissues of the nose, oral cavity, and pharynx by Leishmania spp.
Caused by Leishmania species in Africa and the Americas
Behcet's disease
Inflammatory, multisystemic disorder
Recurrent oral ulcers are the most common feature
Other features include genital ulcers and uveitis
Can also involve visceral organs e.g. GI tract, pulmonary, MSK, cardiovascular and neurological systems
Commonest in Middle East and Asia
Coeliac disease or IBD
Recurrent aphthous ulcers frequently seen in patients with coeliac disease and IBD
Other symptoms include diarrhoea, weight loss
Reactive arthritis (Reiter's disease)
Arthritis which occurs in response to an infection in another part of the body, most commonly genitourinary infections (Chlamydia, Neisseria) or GI infections (Salmonella, Campylobacter)
Can cause painless oral ulcers
Drug reactions
Mouth ulcers can sometimes be caused by certain medications or treatments, such as NSAIDs, beta-blockers and sulfonamides
Skin disease
Lichen planus, pemphigus, or pemphigoid can present with oral ulcers