Is It Bad to Take Metamucil Before Bed? Plus, 7 Other Metamucil FAQs

Feeling constipated is no fun. But laxatives like Metamucil (psyllium) can help get things moving again. Metamucil is an over-the-counter (OTC) bulk-forming fiber laxative that treats occasional constipation. Your healthcare professional may also suggest taking it to boost your daily fiber intake, treat diarrhea, or lower your cholesterol levels.

Metamucil isn’t one single product, though. The brand name refers to a line of products that contain psyllium. These products come in several dosage forms, including a powder you mix into beverages, capsules, wafers, and gummies.

If you’re taking Metamucil to treat constipation, it’s normal to have questions about when to take it, how it works, and when you can expect results. Here, you’ll find answers to these and other frequently asked questions about Metamucil.

1. Is it bad to take Metamucil before bed?

Taking Metamucil right before bed might not be the best idea. It may lead to nighttime bathroom trips and some discomfort. If you take a dose in the evening, it’s best to take it a few hours before bedtime for better sleep.

Metamucil’s active ingredient is psyllium husk, a fiber product that treats constipation by absorbing water and adding bulk to your stool, which makes it easier to pass. 

However, if you don’t drink enough water while taking Metamucil, the psyllium may be less effective. It can also cause dehydration and abdominal cramping. Feeling gassy is possible when taking Metamucil, too. These side effects can make you feel uncomfortable and restless, making it hard to get a good night’s sleep.

Good to know: When you take Metamucil, it’s important to carefully read the product’s directions for use to ensure you’re taking it correctly. You should take each dose with at least 8 oz (a full glass) of water or another cool liquid. This will ensure the medication is as effective as possible and also help you avoid potential side effects.

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2. When is the best time to take Metamucil?

You can technically take Metamucil at any time of the day. But bulk-forming laxatives, including Metamucil, can affect the way other oral medications are absorbed. This means that you might not get the full dose of a medication, leading to a less effective treatment. 

To avoid this, it’s best to take Metamucil 2 hours before or 2 hours after taking other oral medications.

Good to know: It’s recommended to start with one Metamucil dose per day and slowly increase to three doses per day (if needed) until you have regular bowel movements. This will help give your body time to adjust to the increased fiber intake and prevent uncomfortable side effects, such as gas, bloating, and stomach cramping.

3. Can you take Metamucil every day?

Yes, you can take Metamucil every day. But you shouldn’t take it for more than 7 days (1 week) at a time without a healthcare professional’s OK.

Ideally, Metamucil should only be taken for short periods of time to relieve constipation symptoms. Taking laxatives for too long may cause electrolyte imbalances and dehydration.

If your constipation lasts longer than 7 days, talk to your healthcare professional. They may recommend making simple lifestyle changes or trying a different medication. But prolonged constipation might be a sign that a more serious health condition is causing your symptoms. 

4. How does Metamucil work?

After you take Metamucil, it becomes a gel-like substance in the stomach. From there, it moves into your intestines and gets to work. It acts as a source of soluble fiber that dissolves in water. This helps your stool soak up more water, making it bigger and softer, so it’s easier to have a bowel movement.

5. How long does it take Metamucil to work?

Metamucil doesn’t start working immediately. After taking the medication, you’ll usually have a bowel movement within about 12 to 72 hours (1 to 3 days). Some other laxatives work faster, such as magnesium citrate and bisacodyl (Dulcolax), but they have more risks and side effects than Metamucil.

6. What is the downside to taking Metamucil?

The biggest downside to taking Metamucil for constipation is that it doesn’t work right away. It may take a few days for you to notice any improvement in your symptoms. But it shouldn’t take longer than that.

Generally, Metamucil and other bulk-forming laxatives are considered safe to use for most people. But, like with all supplements, Metamucil can cause side effects.

Common Metamucil side effects

The most common Metamucil side effects include:

• Nausea

• Vomiting

• Gas

• Stomach cramping

• Bloating

• Diarrhea

Serious Metamucil side effects

The following Metamucil side effects are more serious. While these side effects are rare, you should let your healthcare professional know right away if you develop any of them.

Rectal bleeding

If you experience rectal bleeding while taking Metamucil, seek immediate medical care. This could be a sign of a serious health condition. Symptoms of rectal bleeding include bright- or dark-red blood in stool, black stool, and blood on toilet paper after wiping. If you notice any of these symptoms, contact your healthcare professional right away.

Bowel obstruction

When you take Metamucil, it needs water to work. Not drinking enough water can lead to a bowel blockage. This can make it hard for stool to move through your intestines, potentially leading to a bowel obstruction.

Symptoms of a bowel obstruction include severe stomach pain, nausea, and vomiting. If this happens, contact your healthcare professional immediately.

Serious allergic reactions

It’s possible to have a serious allergic reaction to psyllium and the other ingredients in Metamucil. If you have an allergic reaction, you may only have mild symptoms, like a localized rash or itching. But more serious symptoms, including trouble breathing and swelling of the face or mouth, are also possible. If you notice any of these symptoms, call 911 or go to the nearest ER right away.

7. What is the best alternative to Metamucil?

If you’re looking for an alternative to Metamucil for constipation, the best option is to increase your intake of fiber-rich foods. Think fruits and vegetables, whole grains, legumes, and nuts and seeds.

Foods that are rich in natural fiber can help promote regular bowel movements and relieve constipation. Just make sure to drink plenty of water to help fiber do its job effectively.

8. Which is better, Miralax or Metamucil?

Choosing the right laxative depends on multiple factors, such as your personal preferences and any other health conditions you have. There haven’t been any head-to-head studies to see whether Miralax or Metamucil is more effective for occasional constipation, so it comes down to what works best for you.

Miralax vs. Metamucil: Different medication classes, dosages, and interactions

Miralax (polyethylene glycol 3350) and Metamucil can both address occasional constipation. But they work differently. Miralax is an osmotic laxative, which means it brings water into the intestines and softens the stool, making it easier to pass. Metamucil adds fiber to stool, making it bigger and softer for easier passing.

Miralax comes as a powder that’s mixed into liquids. It’s taken once a day and, unlike Metamucil, it can be taken with any temperature liquid. Metamucil must be mixed with cool liquid to prevent it from gelling too thick. But Metamucil comes in a variety of dosage forms, such as powder, capsules, wafers, and gummies. And it can be taken up to 3 times a day.

Both Miralax and Metamucil typically take 1 to 3 days to work and are more effective if you’re well hydrated. Because of this, the medications may not be good choices for people who need to restrict their fluid intake (like those with heart failure). Miralax can also pose an issue for people with kidney problems, because it may cause a shift in electrolytes.

If your symptoms are related to a medication that causes constipation, Miralax might be a better choice than Metamucil. This is especially true if you’re taking an opioid such as oxycodone (Roxicodone, OxyContin) or a weight-loss medication such as Zepbound (tirzepatide). Bulk-forming laxatives like Metamucil increase the size of the stool, potentially making it harder for already sluggish intestines to move stool along.

How to save on Metamucil

There are ways to save on Metamucil, which is available as both a brand-name and generic medication. GoodRx may be able to help you save if your healthcare professional writes you a prescription for OTC Metamucil. With a free GoodRx coupon, generic Metamucil’s price may be as low as $ at certain pharmacies.

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Written by:

Nikki Javit, PharmD

Nikki Javit, PharmD, is a clinical pharmacist with certifications in international travel medicine, immunization delivery, and pharmacogenomics. She received her bachelor’s of science in biology from Indiana University Bloomington and her doctor of pharmacy degree from Butler University.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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