| Behcet's disease | It is a systemic disorder characterised by recurrent oral aphthous-like ulcers together with at least two of the following symptoms: genital aphthous-like ulcers, ocular inflammations, skin lesions, vasculitis, transient arthritis of the peripheral joints. |
| Reiter's syndrome | Typical symptoms are arthritis, urethritis, conjunctivitis and 10per cent of patients manifest oral aphthous-like ulcers. |
| Hematinic deficiency | About 25per cent of RAS patients show deficiencies in zinc, iron, folic acid or some vitamins which can affect the immune system and can have an association to RAS. |
| Gastrointestinal disease | Celiac disease can be a reason for a vitamin B and foliate deficiency and may lead to RAS. A complete remission of the aphthae is possible by a gluten-free diet. |
| Sweet's syndrome | The symptomatic triad of the rare Sweet's syndrome comprises fever, erythematous plaques or nodules and an increase in neutrophils. Aphthous-like oral lesions are an often concomitant. |
| Cyclic neutropenia | Symptoms include RAS (especially the minor type), malaise, fever, skin infections and cervical adenopathy for about 3 weeks each time. Gingivitis, loss of alveolar bone and tooth-loss can accompany the cyclic episodes. |
| MAGIC | The 'mouth and genital ulcers with inflamed cartilage syndrome' includes polychondritis, arthritis and cutaneous pustules together with symptoms of Behcet's disease. |
| PFAPA | The 'periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome' includes intervals of that symptoms which start in early childhood and last for years. The patients are completely healthy in between the episodes. |