The symptoms of Crohn’s disease appear when the wall of the affected part of the gut becomes inflamed. The inflammation generally causes one or more of the following:

• Pain – Different people experience different severities of pain. The location of the pain depends on which part of the gut is affected, and will often be on the lower right side of the abdomen as the condition commonly occurs at the lower end of the small intestine (ileum).
• Ulcers – A raw area of the gut wall may bleed. If this happens, blood may be noticed in the faeces. Mouth ulcers are also common.
• Diarrhoea – this can vary from mild to severe, and may contain mucus, pus or blood. Also tenesmus is common which is the feeling a frequent need to go to the toilet, but a lack of anything to pass.
• Feeling generally unwell – Fever and extreme tiredness.
• Loss of appetite – loss of appetite and subsequent weight loss.
• Anaemia – this can occur if a large amount of blood is lost due to other symptoms.
• Anal fissures and rectal bleeding – the skin of the anus may become cracked, bleed and be painful.
• Additional symptons – other symptoms can be experienced, particularly arthritis (inflammation of the joints), inflammation of the eye and inflammation of the liver. Skin rashes can also occur. It is thought that these symptoms may be a reaction by the immune system to Crohn’s.

The level of symptoms may be related to the level of inflammation of the gut.