What Helps Constipation During Chemo (and When to Get Support)

Written By Angie Boxberger

The ultimate plot twist - you expected some nausea and fatigue - but why did nobody warn you about constipation during chemo?!

This is arguably one of the most frustrating and uncomfortable chemo related side effects, but for some reason - constipation often gets overlooked. Like…isn’t this the kind of thing we want to prep for in advance? So why are you finding out by experience?

First off - chemo constipation is SO common and I promise, you didn’t bring this on yourself.

In this blog, we’ll walk through why it happens, what to eat, and real solutions that won’t make you feel worse when you’re probably balancing a handful of other side effects too. 

This blog post will cover food strategies, lifestyle tips, plus how to know when you just need more help (and what to do about it!).




Why Does Chemotherapy Cause Constipation?

So why is constipation so common during chemo anyway?

Well, unfortunately, constipation is a side effect of many chemotherapy regimens. Chemo drugs slow down GI motility (meaning everything inside your gut moves slower too). The slower things move, usually the harder your stool becomes, the more pain/gas you experience, and the more difficult it becomes to pass your stool. 

On top of chemo causing constipation, many supportive medications can cause constipation too. Specifically: pain medications and anti-nausea medications. These medications may be necessary to help with other debilitating side effects, but they tend to add to the constipation conundrum.

Aside from treatment & meds, we can’t forget that chemotherapy changes how well you feel, which trickles down to how you eat, drink, move and so on…

Dehydration during treatment is extremely common - and yes, even when you feel like you “drink a lot of water”....it may still be less than what you need during a treatment season. Cancer treatments require more hydration than normal (think flushing/processing meds), so your usual amount of fluids likely isn’t going to cut it. 

You may also find yourself eating less ⬇️

Less consistent food intake = less consistent bowel movements.

Less eating also leads to less energy (on top of cancer fatigue) which means you may also move your body less (because exercise is the last thing your body wants when fatigue is heavy). The more you sit or rest (the less your body moves) 👉 the less your bowels move. 

Rest assured that none of this is your fault - and it’s ALL fixable (yay!!) - let’s dive into that next!

Read: Common Chemo Side Effects and How to Manage Them



Best Foods for Constipation During Chemo

Okay - obviously we’re going to talk about food - because Hi 👋 dietitian here!

Fiber (start gently):

We can’t talk about constipation relief without talking about fiber. Fiber comes from

  • fruits

  • veggies

  • whole grains

  • nuts/seeds

  • beans

(noticing a plant trend here?)

We have a few kinds of fiber in our foods (soluble & insoluble) but both can be helpful for constipation. The biggest thing to remember with fiber is that you MUST - I repeat, MUST - start slowly when adding it into your diet. You also need to increase fiber in tandem with fluids. If you skip these steps (fluid + slow addition) we risk worsened constipation. No thanks 👎

Try adding in foods like oatmeal, cooked carrots, bananas, lentils, chia seeds


Hydrating foods:

Believe it or not, adding foods that have high water content also help alleviate constipation. Think foods like:

  • watermelon

  • cucumber

  • soups

  • smoothies

…really anything that melts.

Natural “movers”:

These are foods that help move things a long naturally - either by adding fiber/bulk, drawing water into the GI tract (softening stool), or stimulating muscle contractions of the gut (aka movement of stool).

Special awards go to:

  • prunes

  • kiwi

  • flaxseed

  • apple juice

  • hot beverages

  • caffeine (caution with this if you struggle with dehydration or have difficulty drinking enough liquid!)

These foods can naturally support bowel movements.

Optional probiotics:

Sometimes probiotics can help move things along too.

Probiotics support your gut bacteria which can help move things through your digestive system faster.Focus on food sources like yogurt with live cultures, kefir, sauerkraut (if tolerated), tempeh, or aged cheeses. 

*Careful with live cultures if you’re white blood cell counts are low. Always talk to your doctor about supplements before taking. 



Other Tips to Relieve Constipation During Treatment

Aside from food sources, lifestyle patterns and behaviors can play a major role in regulating bowel movements.

Try these chemo safe strategies:

Stay hydrated

No matter what you drink 👉 sip all day (try warm lemon water, broth, herbal tea, especially if you’re sensitive to cold liquids from chemo)

Move your body gently

Short walks (yes, even slow ones), stretching, or gentle yoga can be really helpful.


Establish a regular toilet routine

Yep…same time each day. Even if you don’t “have” to go, move through the motion to start training your body. Yes - this means you need to sit on the toilet even if you don’t end up going (although don’t strain if you don’t need to go).


Consider a squatty potty for positioning

I know you’ve seen ads for this…and if you haven’t, give it a google.

It looks like a joke but it isn’t - this positioning is how our bodies are designed to “go”.



What About Laxatives or Stool Softeners?

If constipation is showing up during treatment, this is one of those areas where support often needs to go beyond just food swaps/additions. Between medications, changes in appetite, hydration dips, and lower activity levels, your digestion can slow down quickly—and sometimes your body needs a little extra help to get things moving again.

There are a few common over-the-counter options your care team may recommend:

  • Miralax (polyethylene glycol): works by pulling water into the stool, making it softer and easier to pass

  • Colace (docusate sodium): a stool softener that helps prevent hard, dry stools

  • Senna: a stimulant laxative that encourages the muscles of the bowel to contract

  • Magnesium (various forms): can help draw water into the intestines and promote a bowel movement

These options all work a little differently, which is why what helps one person may not be the best fit for someone else. Sometimes it’s about softening the stool, sometimes it’s about stimulating movement, and often it’s a combination of both.

In general, these tools can be helpful:

✔When you’ve gone a couple of days without a bowel movement and can feel things slowing down

✔When you know constipation is a predictable side effect of your treatment or medications (like certain anti-nausea meds or pain medications)

✔When dietary changes alone aren’t cutting it—or don’t feel realistic based on your current symptoms


Important: You don’t have to tough it out

There’s a common tendency to “wait this out” or try to “fix it naturally” first—but constipation during treatment isn’t something you need to push through - sometimes that can lead to more problems.

The goal is staying ahead of symptoms so they don’t spiral into something that affects your appetite, energy, nausea, or ability to tolerate treatment. Using a stool softener or laxative when needed isn’t a failure of your nutrition plan, it’s often part of supporting your body through a very real, very common side effect.

If you’re unsure what’s appropriate or when to start, that’s exactly where your care team can step in. And if you’re looking for help on the food/hydration side of things…I know a girl 😉 Apply to Work With Us


What to Avoid if You’re Constipated During Chemo

Now that we’ve talked about what TO do…let’s talk about what to avoid when constipation is slowing you down - literally!

Try to avoid:

  • Dry, low-fiber processed snacks (crackers, pretzels) - the exception here is if you have nausea. Low fiber foods are easier on the stomach (during nausea windows), but they don’t do your constipation any favors. Use low fiber foods until nausea improves, then start gradually adding it back in.

  • High-fat dairy can slow digestion (for some people). If you eat these foods, notice if you can tell a change in your stool patterns.

  • Skipping meals (less volume = slower movement). Our bodies thrive on consistency. Eating less often or skipping meals confuses your GI tract. Why would it need to “push things through” if nothing is coming into the system? Makes sense, right?

  • Overuse of binding supplements like iron or calcium without guidance. If you’re using these supplements, cross check with your oncology team to see if the benefit is worth the risk (aka: constipation).

Check out this blog:What to Eat During Chemo



Supporting Gut Health After Treatment

I’ve heard it over and over—“Ever since chemo, my gut has felt off.”

And honestly, that tracks. Cancer treatments can affect the lining of your gut, which impacts how you digest, absorb, and move food through your system. Gut motility can slow down (or speed up), and your microbiome—the bacteria that help regulate digestion—often takes a hit. It’s not unusual for things to feel off for a while, even after treatment ends.

So what can you do about it?

Start with the basics, and build from there. If you had to pull back on fiber during treatment (which is very common), gradually reintroducing it can help. Bringing back a variety of plant-based foods—fruits, vegetables, grains, legumes—gives your gut the raw materials it needs to rebuild. Including probiotic-rich foods (think yogurt, kefir, fermented foods) can help support that process over time too.


But here’s something else worth considering:

Your gut isn’t just responding to food, it’s also responding to stress.

After everything your body has been through, your system can still be a little on edge. And because your gut and brain are constantly communicating, that stress can show up physically as bloating, irregular digestion, or sensitivity to foods that used to feel fine.

So part of restoring your gut is actually helping your body re-regulate.

I’m talking small, consistent ways that signal safety to your nervous system. This could look like:

  • Getting outside for a short walk (especially after meals)

  • Slowing down while you eat instead of rushing through it - try setting your fork down between bites

  • Taking a few deep breaths before meals to shift out of the “fight or flight” part of your nervous system

  • Gentle movement like yoga or stretching (don’t forget to breathe through this!)

  • Creating some kind of wind-down routine at night to support sleep

I know these sound like “nice habits” in theory, but they actually directly support digestion by helping your body shift into a state where it can actually process food more comfortably. Healthy digestion happens when your body feels safe…safe enough to do normal “housekeeping” activities. When your body in stress mode, housekeeping falls to the wayside.

So yes—what you eat matters. But so does how your body feels while you’re eating and digesting it.

🍓 For more on this, check out this post: Gut Health After Cancer




FAQs About Constipation and Chemotherapy

  • Constipation often starts within a few days after chemo and tends to follow a cycle (worse right after treatment, then improves before the next round) - this is largely related to chemo meds + support meds (ex: nausea or pain meds). However, for some, constipation may persist depending on activity levels, hydration, or treatment. Talk to your doctor or dietitian if you’re struggling with constipation. 

  • Not necessarily—fiber is still important, but tolerance matters. During active symptoms (especially bloating or discomfort), some people do better with: Lower or modified fiber temporarily. Try to include soluble fiber (oats, bananas, etc.) vs. rough/raw fiber. Long-term, fiber helps support regularity, but it should be adjusted, not eliminated, based on your symptoms.

  • Magnesium can help by drawing water into the intestines, making stool easier to pass. It’s commonly used, but not all forms work the same. It may not be appropriate for everyone (especially depending on kidney function or other meds). Best practice is to check with your care team before starting any supplement or laxative.

  • This is very common during treatment—and it directly impacts constipation. Low intake (especially fluids + food volume) can slow gut motility and worsen constipation - which is the opposite of what we want.

    Priorities shift here:

    • Focus on fluids first

    • Small, manageable foods (even low-fiber at times)

    • Support overall intake rather than forcing “perfect” nutrition

  • If you haven’t had a bowel movement in ~2–3 days, it’s worth reaching out.

    Also contact your team if you have:

    • Pain, cramping, nausea, or vomiting

    • Blood in stool

    • Constipation that isn’t improving with basic support or medications

    Early intervention matters—your team can help prevent more serious issues like impaction or obstruction.

Real Client Stories: “No constipation - what a win!”

“Wow wow - two weeks of constipation after chemo last time, but this week, with your team's help, I increased water and had a small change in food. I was good to go with NO constipation! That’s a win win by changing just a few things!” - Margaret, breast cancer survivor

Learn more about working with us!



Need Personalized Support with Chemo Side Effects?

Constipation is extremely common (and super annoying) during cancer treatments. It can impact how you feel, and ultimately how you support yourself during treatments. The good news is that it’s treatable - and often preventable. You may wonder if it’s worth bothering your medical team with and I can assure you - it’s no bother, it absolutely deserves attention and care. You’ll feel better and be able to support yourself more effectively if you have a constipation plan in place. 

  • If you’d like support with treatment side effects (including constipation):

  • Not sure what kind of support you need? Let us help you figure it out. Get in touch with me & let’s talk through where you’re stuck and how we can help.



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Angie Boxberger
Next

Pancreatic Cancer Nutrition – What to Eat During and After Treatment