“GERD, diarrhea and colorectal cancer are examples of gastrointestinal diseases. When examined, some diseases show nothing wrong with the GI tract, but there are still symptoms. Other diseases have symptoms, and there are also visible irregularities in the GI tract. You can prevent and/or treat most gastrointestinal diseases.

GI diseases can be acute or chronic:

• An acute GI disease is one that happens suddenly and lasts a short period of time.
• A chronic GI disease can affect you for many months or years.

They can also be either functional or structural:

• A functional GI disease is when your healthcare provider can’t see any physical or structural issues when they examine your digestive tract.
• A structural GI disease is when your healthcare provider can see evidence of an issue when they examine you.”

Cleveland Clinic (Gastrointestinal Diseases: Symptoms, Treatment & Causes)