Managing constipation from chemo or pain medicine

• Call 911 or go to an emergency department if you have severe abdominal pain together with vomiting and cannot pass stool or wind at all. NCI describes faecal impaction — hardened stool blocking the colon or rectum — as life-threatening and says it requires immediate medical attention.
• Call your care team the same day if you have had fewer than three bowel movements in one week, or you are vomiting, or the pain in your abdomen is building rather than easing. NCI names exactly these as reasons to notify the care team.
• Call your care team within a day or two if stool has become hard enough that you are straining, or a prescribed laxative has stopped working for you.

Do not add extra laxatives on your own while you wait, and do not use suppositories or enemas unless your doctor recommends them. NCI warns that in some people with cancer these can lead to bleeding, infection or other harmful side effects.

NCI describes the mechanism simply: constipation is the slow movement of stool through the large intestine. The longer stool remains there, the drier and harder it becomes — which is why the problem compounds itself if it is left alone.

That detail explains why waiting rarely helps. Time is on the side of the problem, not on yours.

NCI lists several contributors, and most people during treatment have more than one at work.

• Certain cancers affect bowel function directly, including colon, rectal and ovarian cancers and brain tumours.
• Chemotherapy. NCI states that constipation is a common side effect of some types of chemotherapy.
• Medicines, including opioid pain medications, antianxiety drugs and antinausea drugs.
• Lifestyle changes during treatment — reduced activity and an altered diet.

If you started an opioid painkiller and an anti-sickness tablet on the same day you had chemotherapy, you have three causes stacked on top of each other. That is worth saying out loud to your team, because it changes the plan from reactive to preventive.

Fluids. Drinking 8 cups of water or clear liquids per day can help you stay hydrated. NCI notes coffee and prune juice may help, as can hot beverages.

Activity. Try to be active every day, and ask your health care team about exercises you can do. NCI mentions walking, biking and yoga, and includes light bed or chair exercises for people who cannot do more.

Routine. Eat at the same time each day, and keep a record of your bowel movements. The record sounds fussy until you are asked in clinic how long it has been and cannot remember.

Fibre — with a warning. This is the one that catches people out. NCI's advice is to talk with your doctor about dietary fibre, because high-fibre foods and fibre supplements can make constipation worse for some people.

That runs against everything general health advice says, and it is exactly why it belongs in a conversation with your team rather than in a supermarket aisle.

Your doctor may prescribe a laxative. NCI describes the main types: osmotics, which pull water into the bowel; stool softeners; and stimulant laxatives.

The instruction attached to all of them is unambiguous: use only medicines and treatments for constipation that your doctor recommends.

There is a reason for that firmness. NCI singles out suppositories and enemas, saying not to use them unless your doctor recommends them, because in some people with cancer they may lead to bleeding, infection or other harmful side effects. Ask first.

The most useful shift is from treating constipation to preventing it. If you are starting an opioid, ask at that appointment what your bowel plan is rather than waiting until day four.

Keep the record NCI suggests. Bring it with you. And use the escalation guidance at the top of this page as your threshold, so that you are deciding in advance when to call rather than negotiating with yourself at midnight.