Trade/other name(s): Citrucel, Unifiber, SmartFiber
Why would this drug be used?
Methylcellulose is used to treat constipation. Some doctors use it to treat diarrhea as well. You can buy it over the counter, without a prescription.
How does this drug work?
Methylcellulose is a bulk-forming substance that absorbs water and expands in the intestines. The larger volume stimulates the normal forward movement of the intestines (known as peristalsis), which usually results in a bowel movement within 12 to 24 hours. Some people may take longer to have a bowel movement, up to 3 days. Some doctors prescribe methylcellulose to slow down diarrhea.
Before taking this medicine
Tell your doctor…
- If you are allergic to anything, including medicines, dyes, additives, or foods.
- If you have nausea, vomiting, rectal bleeding, unexplained abdominal pain, blocked intestine, or any disease of the stomach or intestine. Something other than constipation may be causing your problem, and laxatives may worsen it.
- About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.
Interactions with other drugs
Bulk-forming laxatives can keep tetracycline (an antibiotic) from working.
Other medicines may not work as well if taken at the same time as laxatives. Do not take methylcellulose within 2 hours of other medicines.
The soft chew form of methylcellulose contains calcium, which can block certain drugs from being absorbed by the body. It can also affect the actions of medicines such as digoxin (Lanoxin), etidronate (Didronel), phenytoin (Dilantin), and tetracycline (Sumycin). Do not take calcium within 2 hours of taking other medicines.
Check with your doctor, nurse, or pharmacist about other medicines, vitamins, herbs, and supplements, and whether alcohol can cause problems with this medicine.
Interactions with foods
No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.
Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.
How is this drug taken or given?
Methylcellulose is available as powder that you can mix with at least 8 ounces of juice or water. Drink it right after mixing before it gets too thick to drink. Methylcellulose also comes in caplets and candy-flavored chews. Either form should be taken with at least 8 ounces of water.
Take this drug exactly as prescribed by your doctor or follow the directions on the label. If you have any questions or are confused by the instructions, talk to your doctor or nurse. Make sure the container is tightly closed and stored away from heat and moisture and out of the reach of children and pets.
Some forms of methylcellulose contain sugar. If you have diabetes, check with your pharmacist to be sure you get methylcellulose without sugar.
If you are on a low-sodium diet, check the sodium content or ask your pharmacist before you buy methylcellulose.
Never try to swallow methylcellulose powder in dry form. Always mix powdered forms with liquid and take as directed on the package. Take caplets or flavored chews with plenty of water or juice. Drinking extra fluids will help methylcellulose work and reduce the chance of blocking the esophagus or intestine. Call your doctor if you have vomiting, trouble swallowing, abdominal pain, bleeding, or no bowel movement after 3 days.
Call your doctor right away if you have a skin rash or welts (hives), itching, or trouble breathing or swallowing (lump in the throat).
To help avoid constipation, try to drink 2 to 3 quarts of fluid a day. Increase the amount of fiber you get from foods by eating fruits, vegetables, beans, peas, and whole-grain breads and cereal. Talk to your doctor about what kind of exercise may help you.
Possible side effects
You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.
- gas or bloating
- stomach cramps
- blocked esophagus, stomach, or intestines if this medicine is not properly diluted or drunk immediately after mixing, or if you are dehydrated*
- allergic reaction with itching, skin rash, trouble breathing or swallowing*
There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.
This drug appears to pre-date the current FDA approval process, which would mean it was not required to get formal FDA approval.
Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.
Last Revised: 11/17/2009