Mouth ulcers are painful, open sores inside the mouth caused by a break in the mucous membrane. They may also be known as canker sores. Mouth ulcers are often caused by minor injuries. Aphthous, or recurring, ulcers do not have an exact known cause but may result after minor injuries, during times of stress, after eating certain foods, and even during menstruation. Mouth ulcers may also be caused by viruses, infections, medication reactions and skin conditions. Treatment options include soothing and/or antiseptic mouthwash, local anaesthetics, paracetamol, corticosteroids, fluids, avoiding spicy or sour foods, stress management, herbal remedies, homoeopathy, aromatherapy, and nutritional therapy.