How diarrhoea severity is graded during cancer treatment

Call 911 if you are too weak or dizzy to stand, cannot keep any fluid down, or become confused or unresponsive. NCI describes dehydration from severe diarrhoea as life threatening. It warns that grades 3 and 4 diarrhoea can be life threatening in themselves.

A fever changes the timing. On chemotherapy the CDC counts it as a medical emergency, so telephone your team the moment you see the reading, day or night, and go to an emergency department if they cannot be reached.

Call your care team the same day if you have blood or mucus in your stools, belly pain or cramping, fever, dizziness, or about four or more bowel movements above your usual daily number. NCI names fever, dizziness, weight loss and blood in stools among the symptoms to report. If you are on an immune checkpoint drug, do not wait for a high count at all: colitis is treated early, and a modest rise with pain or blood is enough reason to ring.

If your team has written you a lower number than the ones here, theirs is the one to use.

Say on the phone which treatment you are receiving. Are you on immunotherapy? Say so early in the call.

Clinicians grade side effects. Diarrhoea is one where the grade is easy to understand. NCI describes it as extra bowel movements measured against your own daily normal.

Grades 1 and 2 cover up to six bowel movements above your normal daily number. NCI says these can usually be managed at home. Grades 3 and 4 sit above that. NCI states they can be life threatening.

One caution about using those grades as a rule for yourself. They were written so that clinicians and trials could record severity in a consistent way. They were not written as a decision point for when to pick up the phone. Your own call threshold comes from your team and your treatment, and on immunotherapy it is usually set well below the grade 3 line.

Your normal is the reference point. That is why nobody can grade this for you without asking.

This is what a counting scale means in practice. Do you know your usual pattern? If not, you cannot report a change accurately. And the person on the phone is working blind.

Worth noting down:

• How many bowel movements a day you normally have
• How many you had today
• Whether the stool is soft, loose or watery
• Whether there is any blood
• What you have managed to drink

A note on your phone is enough. It is the difference between saying it is bad and saying it went from two to nine.

NCI lists several causes of diarrhoea during cancer treatment. The descriptions are not the same.

For chemotherapy, NCI explains that the drugs destroy rapidly dividing cells. That includes healthy cells lining the digestive tract. For immunotherapy, the wording changes. Certain drugs cause inflammation of the colon, called colitis. The colon is the large bowel.

That is a different mechanism. It is why teams treating people on immunotherapy tend to ask about bowel changes at every visit. NCI does not publish a separate counting scale for immunotherapy on this page. The counting stays the same. The underlying problem may not.

Radiation to the abdomen, pelvis or rectum is also listed as a cause. So are surgery on digestive organs, targeted therapy, and bone marrow or stem cell transplant.

NCI also lists causes that have nothing to do with the cancer drug itself. Infections are one. A weakened immune system makes them more likely. Antibiotics, anti-inflammatory drugs, and some diabetes and depression medicines appear on the list. So do supplements and herbal products.

Stress and anxiety after a cancer diagnosis are named too. That does not make the symptom imaginary. And it does not mean it should go unreported.

For grades that can be handled at home, NCI's suggestions are simple.

• Drink clear liquids such as water and broth, at room temperature
• Eat small, frequent meals of low-fibre foods
• Include foods with sodium and potassium, such as potatoes, bananas and broth
• Avoid alcohol, dairy, spicy foods and high-fat items
• Keep the anal area clean using warm water

Medicines exist too. NCI mentions loperamide and diphenoxylate with atropine among what a doctor may prescribe. Probiotics or fibre supplements may also be offered. Ask before you start any of them.

The dangerous pattern is a slow one. Each day is a little worse than the last. Nobody rings. Dehydration arrives quietly.

Is today worse than yesterday? Was yesterday worse than the day before? That is the moment for the phone call. Make it even if no single day felt alarming on its own.