Herb & supplement monograph

Manna Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Manna interacts with medications. The heart of this page is the interaction list — every drug Manna is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Manna is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Manna Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Manna drug interaction appears low for most people, especially at typical amounts. None of the listed interactions are rated major, and all of them rest on theoretical concerns rather than effects documented in human studies.

Interactions deserving the most attention

The combinations most worth watching involve narrow-margin medicines where fluid or potassium shifts matter. Manna contains mannitol, which acts as an osmotic laxative, and overuse could cause diarrhea or electrolyte loss. In theory, that could raise bleeding risk with warfarin, increase side effects from digoxin, or worsen potassium loss with diuretics. Pairing manna with stimulant laxatives could also compound fluid and electrolyte loss.

What the rest of the list means

Although a long list of medications appears here, nearly all of these concerns trace back to one simple mechanism: manna's laxative effect, mainly with heavy or prolonged use. None of these interactions have been confirmed in people, so a listed medication does not mean the combination has actually caused harm. Used occasionally and in moderation, manna is unlikely to meaningfully affect most prescriptions.

Check your medications against Manna

Based on HelloPharmacist’s Manna interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Manna

99 medications have a known interaction with Manna, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Manna using our pharmacist-reviewed interaction data.

AI summaries are generated from our Manna interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Manna combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Manna affects

Every type of medication (drug category) Manna is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 4 drug categories Manna interacts with

Digoxin (lanoxin)Diuretic DrugsStimulant LaxativesWarfarin (coumadin)

Digoxin (Lanoxin)

Theoretically, manna might increase the risk of adverse effects when taken with cardiac glycosides.
Manna contains mannitol, which acts as an osmotic laxative. Overuse or abuse of manna might increase the risk of adverse effects from cardiac glycoside drugs.

Likelihood Possible Evidence D

Diuretic Drugs

Theoretically, manna might increase the risk of hypokalemia when taken with diuretic drugs.
Manna contains mannitol, which acts as an osmotic laxative. Overuse of manna might compound diuretic-induced potassium loss, increasing the risk of hypokalemia.

Likelihood Possible Evidence D

Stimulant Laxatives

Theoretically, manna might increase the risk for fluid and electrolyte loss when taken with stimulant laxatives.
Due to the osmotic laxative effects of manna, concomitant use with stimulant laxatives might compound fluid and electrolyte loss.

Likelihood Possible Evidence D

Warfarin (Coumadin)

Theoretically, manna might increase the risk of bleeding when taken with warfarin.
Manna has osmotic laxative effects. In some people manna can cause diarrhea. Diarrhea can increase the effects of warfarin, increase international normalized ratio (INR), and increase the risk of bleeding.

Likelihood Possible Evidence D

Monograph

Manna: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Manna is the dried, sweet sap of the flowering ash tree (Fraxinus ornus) and is best known as a gentle, mild laxative because it contains a sugar alcohol called mannitol. It is generally considered mild and is sometimes used for occasional constipation, but high-quality modern studies are limited, so talk with your pharmacist or doctor before using it.

Scientific name: Fraxinus ornus
Family: Oleaceae
Part used: Dried sap (exudate) from the bark and stems
Common forms: Dried flakes or pieces, syrup, powder, and as an ingredient in laxative products

People commonly use it for

Gentle constipation relief
Mild laxative for children and elderly
Natural sweetener
Occasional bowel softening

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally mild but can cause loose stools, gas, and cramping, especially at higher amounts.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Manna is a sweet, dried sap that comes from the flowering ash tree (Fraxinus ornus), a tree that grows in southern Europe and parts of the Mediterranean, especially in Italy. When the bark is cut, the tree oozes a sap that hardens in the air into pale, sugary flakes or chunks. These are collected and dried to make the product sold as manna.

The word "manna" appears in ancient and religious texts as a food, but those references may describe different substances. In the world of herbs and supplements today, manna usually means the dried sap from the flowering ash tree.

People have used manna for a very long time mainly as a gentle laxative and as a natural sweetener. Because it is mild, it has traditionally been given to children and older adults for occasional constipation.

How it works

Manna contains a sugar alcohol called mannitol, along with other natural sugars. Mannitol is not fully absorbed by the gut. Instead, it stays in the intestine and draws water in by a process called osmosis. This added water makes the stool softer and easier to pass, which is why manna acts as a gentle laxative.

This osmotic effect is the same general way that other sugar-alcohol laxatives work. Most of what is known comes from the chemistry of mannitol and traditional use rather than from large modern studies of manna itself.

Effectiveness

Does Manna work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 1 use evaluated

1 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Manna, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 1 condition — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Constipation

Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral manna for constipation, there is insufficient reliable information about the clinical effects of manna for this purpose.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Manna is generally considered mild, which is one reason it has been used in children and the elderly. Still, like any laxative, it can cause unwanted effects, especially at higher amounts.

People with ongoing belly pain, blockage symptoms, or unexplained changes in bowel habits should see a doctor before using any laxative. Those with diabetes should know that manna contains sugars and sugar alcohols. People who are sensitive to sugar alcohols may get gas, bloating, or diarrhea.

Because there is little reliable safety information for pregnancy and breastfeeding, it is safest to avoid manna during these times unless your doctor or pharmacist approves it. Do not use manna for long periods without medical guidance, since regular laxative use can lead to dependence and electrolyte problems.

Side effects

The most common side effects are related to its laxative action and include loose stools, diarrhea, gas, bloating, and stomach cramps. These are more likely with larger amounts.

Overuse of any laxative can cause dehydration and changes in body salts (electrolytes), which can be serious. Allergic reactions are uncommon but possible. Stop using manna and seek care if you have severe cramping, ongoing diarrhea, or signs of an allergic reaction such as rash, swelling, or trouble breathing.

Manna: Reported Adverse Effects

Documented safety reports on Manna from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, manna seems to be generally well tolerated.

Most Common Adverse Effects:

Orally: Flatulence, nausea.

Reports by condition

Flatulence Gastrointestinal

Orally, manna has been reported to cause flatulence and nausea.

Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no official standardized dose of manna for supplement use. Amounts have traditionally varied based on the person's age and how strong a laxative effect is needed, with smaller amounts used for children.

If you choose to use a manna product, follow the directions on the label and start with the lowest amount. Because doses are not well standardized and effects can vary, it is best to check with your pharmacist or doctor for the right amount and to make sure it is appropriate for you.

Pregnancy & Breastfeeding

Manna & Pregnancy

Insufficient reliable information

Insufficient reliable information available; avoid using.

Manna & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoid using.

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 3 references that drive our Manna monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

Brand directory

Brands that make products with Manna

3 brands in our database make a supplement containing Manna.

Flora 215 products NatureWorks 16 products Pure Herbs 634 products

Product directory

Supplement products with Manna

27 products in our database contain Manna. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Manna: Common Questions

What is Manna used for, and does it work?

People use Manna for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.

Does Manna interact with prescription medications?

Yes. We list 99 medications with a known interaction with Manna. Use the checker above to see how Manna interacts with a specific drug.

How are Manna interactions rated?

Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.

Is it safe to take Manna with my medications?

It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.

Where does this Manna interaction information come from?

Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.

What is Manna used for?

Manna is most often used as a gentle laxative for occasional constipation and is sometimes used as a natural sweetener. It works because of a sugar alcohol called mannitol that helps soften stool.

Is Manna safe?

Manna is generally mild and has long been used even in children, but it can cause gas, cramping, and diarrhea, especially in larger amounts. Avoid long-term use without medical advice and talk to your pharmacist if you have ongoing digestive problems.

Can I take Manna while pregnant or breastfeeding?

There is not enough reliable safety information for pregnancy or breastfeeding, so it is best to avoid it during these times unless your doctor or pharmacist says it is okay.

Is Manna safe for people with diabetes?

Manna contains sugars and the sugar alcohol mannitol, so people with diabetes should use caution and check with their healthcare provider before using it.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Keep exploring

Products that contain Manna

A rotating sample of real supplements in our database that list Manna — open any to see its full ingredients and every drug interaction we check.

See all 27 products with Manna →

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Manna Drug Interactions, Uses, Effectiveness, Safety & More

Your Choice:

Manna Drug Interactions: The Bottom Line

Drugs that interact with Manna

Don’t want to scroll the list? Just ask.

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Likelihood — How Well It’s Documented

Where This Data Comes From

The kinds of drugs Manna affects

Manna: Uses, Safety & Side Effects

Overview

How it works

Does Manna work?

Safety & precautions

Side effects

Manna: Reported Adverse Effects

Dosing

Manna & Pregnancy

Manna & Breastfeeding

References & further reading

Brands that make products with Manna

Supplement products with Manna

Manna: Common Questions

Related supplements & herbs

Products that contain Manna

Have a question about Manna?