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Overview: Psyllium is used to help prevent and relieve occasional constipation. Common side effects may include feeling bloated or changes in your pooping habits. If you do not take psyllium with enough water, it can cause you to choke. You should drink at least 8 ounces of water or other liquid with each dose of psyllium. Psyllium is available in many dosage forms, including capsules that you swallow and powders that you mix in liquid before swallowing.

Uses

What is psyllium used for?

Psyllium is fiber laxative commonly used to help prevent or relieve occasional constipation.

Psyllium may also be used as a fiber supplement.

Psyllium may also be used for other conditions as determined by your health care provider.

How does psyllium work (mechanism of action)?

Psyllium is a type of fiber that works as a bulking laxative. It makes your stool (poop) bulkier and softer and helps pull water into your intestines. This helps poop pass more easily.

How is psyllium supplied (dosage forms)?

Brands and other names

  • Fiber-Caps
  • Konsyl
  • Metamucil
  • Reguloid

Dosage forms and strengths

Psyllium is available in various strengths and dosage forms that are taken by mouth.

How should I store psyllium?

Psyllium should be stored at room temperature, between 59 F and 86 F (15 C and 30 C). Keep the container tightly closed to protect it from moisture. Store in a cool, dry place.

Side Effects

What are the most common side effects of psyllium?

The most common side effects of psyllium are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Feeling bloated or gassy
  • Stomach cramps
  • Changes in your pooping habits

There may be other side effects of psyllium that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of psyllium?

While less common, the most serious side effects of psyllium are described below, along with what to do if they happen.

Severe Allergic Reactions. Psyllium may cause allergic reactions, which can be serious. Stop taking psyllium and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Choking. Taking psyllium without enough fluid may cause it to swell up and block your throat or food pipe. This could cause choking. You should take each dose of psyllium with at least 8 ounces of water or other liquid to decrease this risk. Get medical help right away if you have chest pain, vomiting, or trouble swallowing or breathing after taking psyllium.

Warnings & Precautions

Who should not use psyllium?

Allergies to Ingredients. People who are allergic to any of the following should not take psyllium.

  • Fiber-Caps
  • Konsyl
  • Metamucil
  • Psyllium
  • Reguloid
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific psyllium products they stock.

Trouble Swallowing. Do not take psyllium if you have trouble swallowing or if you have narrowing of your esophagus. Psyllium must be swallowed, and the medicine may swell and make swallowing more difficult. 

Symptoms of a Serious Stomach Problem. Psyllium should not be taken without talking with your health care provider first if you have symptoms of a serious stomach problem. This can include symptoms such as stomach pain, nausea, or vomiting, blood in your poop, or a sudden change in pooping habits that lasts for 2 weeks or longer.

What should I know about psyllium before using it?

There are multiple psyllium products available, and they may be taken in different ways. Read and follow the directions on the product label or take psyllium as directed by your health care provider.

If you have not taken psyllium before, you should usually start at a low dose and slowly increase the dose, as needed. This can help your body adjust to the increased fiber intake. 

Keep psyllium out of the reach of children.

Take psyllium capsules with at least 8 ounces (a full glass) of water or another fluid. Taking it without enough liquid may cause choking.

Mix psyllium powder with at least 8 ounces (a full glass) of cold water or another fluid. Stir the mixture quickly and drink it right away.

After taking psyllium, it is normal to poop in about 12 to 72 hours. 

Stop taking psyllium and contact your health care provider if you have any of the following.

  • Rectal bleeding or blood in your stool (poop)
  • Constipation that lasts for 7 days or longer
  • You do not poop after taking the medicine

Psyllium may affect how well other medicines work. If you take any other medicines by mouth, you should usually separate them from psyllium. In general, take psyllium at least 2 hours before or 2 hours after your other medicines. Talk to your health care provider if you have any questions or concerns.

Do not flush psyllium down the toilet or wash it down the sink. It may cause a clog. Instead, throw it away in the trash.

If you have phenylketonuria (PKU), check all of the ingredients on your psyllium product before taking it. Some psyllium products may contain phenylalanine, which can be dangerous for people with PKU. Ask your pharmacist if you need help finding a psyllium product that is safe for you. 

What should I tell my health care provider before using psyllium?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if psyllium is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Stomach pain, nausea, or vomiting
  • Rectal bleeding
  • Sudden change in pooping habits that lasts for 2 weeks or longer
  • Constipation that lasts for more than 1 week
  • Trouble swallowing

Other Medicines and Supplements. Psyllium may interact with other medicines and supplements. Before taking psyllium, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take psyllium while you are pregnant or trying to get pregnant.

Breastfeeding. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take psyllium while breastfeeding.

Interactions

Does psyllium interact with foods or drinks?

There are no known interactions between psyllium and foods or drinks.

There are no known interactions between psyllium and alcohol. It is possible that alcohol may worsen constipation.

Does psyllium interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

Psyllium may affect the absorption of some other medicines. Tell your health care provider about all medicines that you take or have recently taken.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much psyllium?

If you or someone else has used too much psyllium, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of psyllium?

Psyllium is usually meant to be taken only when needed. Use it according to the product instructions or as your health care provider recommends. Do not take double or extra doses.