Diarrhea could occur in 3 ~ 4 weeks from the starting of radiation therapy and it will gradually disappear after the therapy.

The gastrointestinal tract reaction against radiation is highly sensitive. The mechanism of radiation triggered diarrhea is mainly divided into two:

• Injury on the mucus of gastrointestinal tract.  
• Affecting peristalsis and producing symptoms.

Symptoms

• Upper abdomen radiation: Poor appetite, nausea, vomiting, and abdominal pain.
• Lower abdomen radiation: Possible abdominal pain and diarrhea.

Handling Method

• Unless otherwise restricted by medical advice during the diarrhea period, the patients should drink 2000 c.c. of water daily to supply for the water loss from body.  
• Replace 3 meals a day with multiple meals in small amount.
• Eat low-fiber food such as yogurt, rice, noodle, grapefruit juice, wheat germ, poached egg, bread, fat-free chicken, steamed or baked fish or lean meat.
• Take low-residue diet with high content of protein and calorie : egg, meat soup, apple juice, toast, soft vegetable (gourd).  
• Lactobacillus increases the probiotics in gastrointestinal tract and adjusts intestinal flora to improve symptoms of diarrhea. 
• Since diarrhea could cause the body to lose its potassium ion and hence patients are advised to take food with high content of potassium such as banana, citrus, and vegetable and fruit juice. However for special disease such as diabetes and nephropathy, please consult with the physician. 
• Avoid eating food with greasy, high-in-fat, deep-fried, high-fiber or irritating ingredients ( strong condiments, spicy and salty ).
• Do not eat food with high fiber content such as lettuce, fruit, whole-wheat bread, cabbage, corn, oat, carrot, dried nuts and cauliflower.
• Restrict food and drinks containing caffeine such as coffee, strong tea, cola, and chocolate. 
• In the event of lactose intolerance, avoid milk or other dairies.
• Avoid wiping the anus with force but gently clean the anus with lukewarm water after using the bathroom. Take a bath with lukewarm water and apply Vaseline or physician prescribed ointment on the skin surrounding the anus.  

• Follow the physician prescription for taking obstruent to effectively alleviate the symptoms.