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Staying Regular with Laxatives

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I'm not sure which laxatives to take. Where do I start?

If you don’t have a daily constipation plan and aren’t sure where to start, most doctors recommend starting with:

If you think this will be too much for you, you can start with just 2 tablets of senna in the evening.

Senna (Senakot),
8.6 mg tablets

Take 2 tablets in the morning, and 2 tablets in the evening.

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I don't like Senna. Do I have another option?

If you prefer not to take Senna, an acceptable alternative is to use polyethylene glycol (Miralax) instead:

*Senna usually works faster than Miralax®, but it is more likely to cause cramping and diarrhea.  Miralax® is gentler, but it is more likely to cause bloating.

Polyethylene glycol (Miralax),
17 g capfuls

Take 1 capful once per day.

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I'm still constipated. How do I adjust my laxatives?

If you are constipated despite your daily laxatives, it is usually safe to increase how much Senna or Miralax® you are taking – just don’t take more than the maximum recommended dose (8 tablets of Senna per day, or 34 grams of Miralax® per day) unless specifically instructed by your doctor.

When should I increase my laxatives?

Most cancer doctors and nurses recommend increasing your laxatives if you have not had a good-sized bowel movement in more than 1 or 2 days.

If you haven’t had a bowel movement in 4 or more days, go to My Constipation Rescue Plan.

How should I increase my laxatives?

If you report your constipation in your daily survey, we will give you specific advice on what to do with your laxative doses. If you choose not to report your constipation, here are some guidelines for what to do if you haven’t had a good-sized bowel movement in more than 1 or 2 days:

Continue taking any laxatives that your care team has prescribed, and:

Step 1

Double your dose of Senna, 

up to a maximum of 4 tablet twice per day. If you are not yet taking Senna, start taking 2 tablets twice per day.

Wait 24 hours. If no bowel movement, go to step 2.

Step 2

Double your dose of Miralax, 

up to a maximum of 17g twice per day. If you are not yet taking Miralax, start taking 17g once per day.

Wait 24 hours. If no BM,

go to step 3.

Step 3

Take the maximum dose of

Senna (4 tabs twice a day), and Miralax (17 g twice per day).

If you have already been taking this, continue taking it, call your care team, and follow the instructions in your Constipation Rescue Plan.

Wait 24 hours. If no BM, go to step 4.

Step 4

First, notify your care team about your severe constipation. Then, follow the instructions in your Constipation Rescue Plan.

If at any point you develop severe abdominal pain, vomiting, fever, or if you don’t pass gas from your bottom (or ostomy) – NOTIFY YOUR CARE TEAM IMMEDIATELY. This could be a sign of a more serious problem like a blockage of the bowels.

What do I do after my bowels start moving again?

Once you have a good-sized bowel movement, continue taking the laxatives that helped you have a bowel movement. If you are having loose stools, you may want to go back one step on this laxative plan. Your care team can help give you advice.

What should I do if I have diarrhea?

If your laxatives are causing diarrhea, stop taking your laxatives. Once your diarrhea has been gone for a day, restart your laxatives at a lower dose. There isn’t a right or wrong way to decrease your laxatives, but a common approach is to cut the dose of your Senna or your Miralax in half. 

Your care team can give you more advice if you need it.

For example, if you have diarrhea when taking:

17g of Miralax, and

4 tablets of Senna at night.

Reduce to

17g of Miralax, and

2 tablets of Senna at night.

Want to learn more?
Check out these articles:

© 2020 Dana-Farber Cancer Institute, Inc. (Dana-Farber). All rights reserved.

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