Straining on the toilet, having painful cramps, or feeling bloated? Constipation happens to many people from time to time, but it may happen more often during kidney cancer treatment.

Kidney cancer itself is not a common direct cause of constipation. You’re more likely to have infrequent bowel movements because of cancer treatments, pain medications, changes in diet or fluid intake, or lower activity levels.

In this guide, we’ll explain the connection between kidney cancer and constipation and how to cope with your symptoms.

How Kidney Cancer Might Contribute to Constipation

Kidney cancer might contribute to constipation in several ways:

• There could be pressure on the intestines from a tumor.
• Medications may cause constipation as a side effect.
• Cancer can increase the amount of calcium in the blood, sparking a chain reaction that leads to constipation.
• Living with cancer can cause changes to your diet and activity levels.

Tumor Pressure

The kidneys sit behind the abdominal organs, toward the back of the body. In some cases, a large kidney tumor or cancer that has spread may press on nearby organs or tissues. This pressure could slow stool (poop) movement through the bowels, like how a lane closure slows traffic on a busy highway.

Your digestive system continues to pull water from your stool regardless of whether the stool is moving or not. So, it tends to get drier and firmer the longer it stays in your body. This can make it increasingly difficult to have a bowel movement.

Sometimes tumors can also push on nerves in the spine that control the digestive system. This can also cause constipation.

Medication Side Effect

Constipation is a possible side effect of certain cancer medications, which can add an extra layer of discomfort to the treatment process.

One MyKidneyCancerTeam member wrote, “My second infusion of Keytruda is coming up. I pray there is not another constipation event — that would certainly lead to a change of treatment direction.”

Constipation can worsen if you take more than one medication that causes this side effect. Here’s a closer look at common culprits prescribed during kidney cancer treatment.

This isn’t a complete list, so talk to your cancer care team to learn about other medications that may increase your risk of constipation.

Targeted Therapies

Targeted therapies destroy cancer cells while minimizing damage to healthy cells. Certain targeted therapies for kidney cancer can cause constipation because they affect the nerve supply inside your gut.

Normally, these nerves communicate with your intestinal muscles, prompting them to gently push stool farther along. When this communication is disrupted, stool may sit in the intestines longer than usual.

In clinical trials, constipation occurred in:

• 25 percent of people taking cabozantinib (Cabometyx)
• 29 percent of people taking lenvatinib (Lenvima) in combination with pembrolizumab (Keytruda)
• 23 percent of people taking sunitinib (Sutent)
• 20 percent of people taking axitinib (Inlyta)
• 20 percent of people taking temsirolimus (Torisel)
• 14 percent of people taking everolimus (Afinitor)
• 13 percent of people taking belzutifan (Welireg)

This isn’t a full list, and some targeted therapies are far less likely to cause constipation.

Opioids

Opioid pain medications can slow movement in the digestive tract, reduce fluid in the intestines, and make it harder for stool to pass. This can lead to opioid-induced constipation.

High Blood Pressure Medications

People being treated for certain types of kidney cancer may experience hypertension (high blood pressure).

Medications used to control high blood pressure, such as calcium channel blockers and beta-blockers, may lead to constipation because they relax the gut muscles that move stool along.

Anti-Nausea Medications

If you experience nausea or vomiting as a side effect of your cancer treatment, your oncologist may prescribe antiemetic (anti-nausea) medication to help you feel better. Constipation is a possible side effect of these types of drugs.

For example, clinical trials found that 9 percent of people undergoing chemotherapy that can cause nausea reported constipation while taking ondansetron. Ondansetron is a type of antinausea medication used to manage nausea and vomiting symptoms associated with cancer treatment.

Metabolic Changes

Kidney cancer can affect metabolism (how the body processes nutrients and minerals). These changes may lead to hypercalcemia (high calcium levels in the blood), which can cause symptoms like constipation.

Calcium plays an important role in helping nerves and muscles work properly, but too much calcium can slow nerve signals. When the nerves that control your intestines slow down, the muscles in your digestive tract also move more slowly. This can lead to constipation.

Changes in Lifestyle Habits

During kidney cancer treatment, you may feel less hungry, drink less, or be less physically active than usual. These changes can make it harder to have regular bowel movements:

• Not moving enough can reduce muscle tone in your abdomen and bowel. This can slow the movement of stool through your gut, making constipation more likely.
• Dehydration (not drinking enough fluids) can make stool hard and difficult to pass.
• Fiber — especially soluble fiber (a type of fiber that helps hold water in stool) — helps keep stool soft and easier to pass. Constipation may be a sign that you need more fiber in your diet.

Other Common Causes of Constipation

Constipation can also be caused by plenty of factors that aren’t related to cancer.

For example, other medical conditions can also put you at a higher risk of constipation, such as:

• Diabetes
• Depression or anxiety
• Thyroid problems
• Spinal cord injury
• Stroke
• Multiple sclerosis
• Parkinson’s disease
• Hypokalemia (not enough potassium in the blood)

Hormone shifts may also be to blame for constipation. In particular, high levels of progesterone can cause muscles in the digestive tract to move slower.

Waiting too long to go to the bathroom can also cause constipation. Stool becomes firmer and drier the longer you hold it in, and this makes it difficult to pass when the time comes. Listen to your body and try to go to the bathroom when you feel the urge.

How To Manage Constipation With Kidney Cancer

Making a few changes to your daily routine could help you manage constipation with kidney cancer. Consider these tips:

• Eat more fiber-rich foods while following any mineral restrictions.
• Drink more water throughout the day while remaining within the limits of your fluid restrictions (if applicable).
• Walk or move more often throughout the day.

When you’re struggling with a bout of constipation, laxatives can help. However, it’s important to check with a healthcare provider before taking any laxative, as some can be harmful for people with kidney problems.

For example, laxatives that contain magnesium or phosphate should be avoided due to the risk of hypermagnesemia (too much magnesium) or hyperphosphatemia (too much phosphorus).

Other laxatives that may not be appropriate for people with kidney conditions include:

• Mineral oil
• Polyethylene glycol (PEG) with electrolytes
• Sorbitol

Before using any laxative, talk to your healthcare provider to make sure it’s safe for you.

When To Talk to a Doctor

Constipation can be uncomfortable and, in some cases, may lead to serious complications like bowel obstruction (a blockage in the intestines). Tell your care team if you’re dealing with constipation so they can help you find relief. Ask what kinds of laxatives are safe for you and how often you can take them.

Your oncologist will carefully balance side effects like constipation with your dietary and fluid needs and the benefits of your cancer treatment. They can review your plan to see if anything can be adjusted to help ease constipation.

Severe constipation can sometimes lead to fecal impaction (when hard stool gets stuck and can’t be passed) or a bowel obstruction. Learn the warning signs so you know when to seek emergency care:

• No bowel movement for three or more days
• Abdominal (belly) pain
• Lower back pain
• A feeling of pressure in the rectum
• Difficulty urinating or urinating less often than usual
• Nausea and vomiting
• Watery or “explosive” diarrhea (which may leak around the blockage)
• Rapid heartbeat
• Confusion
• Dizziness
• Bloating
• Signs of dehydration (such as dry mouth or dark urine)

Join the Conversation

On MyKidneyCancerTeam, people share their experiences with kidney cancer, get advice, and find support from others who understand.

What has eased or worsened your constipation during kidney cancer treatment? Let others know in the comments below.