Drug & supplement interaction

Manna + Magnesium Hydroxide (OTC drug)

Magnesium Hydroxide (OTC drug) brand name: Milk of Magnesia (MOM).

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Manna has a moderate interaction with Magnesium Hydroxide (OTC drug). Theoretically, manna might increase the risk for fluid and electrolyte loss when taken with stimulant laxatives.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Manna and Magnesium Hydroxide (OTC drug)

Here is the interaction we found between these two, with the evidence behind it.

Moderate

STIMULANT LAXATIVES

Why this applies to Magnesium Hydroxide (OTC drug)

Magnesium Hydroxide (OTC drug) falls under STIMULANT LAXATIVES — the group Manna interacts with.

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.
Severity Moderate Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version: both of these work by pulling extra water into your gut. Milk of Magnesia (magnesium hydroxide) is a saline laxative that draws water into the bowel to soften stool, and manna does much the same thing thanks to its mannitol. So if you use them together, you're essentially doubling up on the same action.

The concern is that combining them could move too much water and minerals out of your body. That can lead to loose or watery stools, cramping, dehydration, and shifts in electrolytes like magnesium and potassium. To be fair, this is a theoretical caution based on how they work, not proven harm, but it's a reasonable one. Please check with your pharmacist or doctor before pairing them, especially if you take them often.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Manna Also Interacts With Other Medications

Manna has 98 moderate known drug interactions in our database — the Magnesium Hydroxide (OTC drug) one above is one of them. If you take anything else, check it against the full list below.

Moderate 98 No known interaction 2,732 (incl. Magnesium Hydroxide (OTC drug))
Taking anything else?

Check Another of Your Medications Against Manna

Covers the 2,830 medications we’ve checked against Manna. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Magnesium Hydroxide (OTC drug)

This page covers Manna only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Magnesium Hydroxide (OTC drug) page lists 46 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Jalap (major), Oleander (major), Alder Buckthorn (moderate) and Aloe (moderate).

By severity: 3 major · 34 moderate · 9 minor.

From our pharmacist’s overview on the Magnesium Hydroxide (OTC drug) page

“Milk of magnesia (magnesium hydroxide) is the medicine-cabinet fix for constipation, and most of the 46 supplements known to interact with it come from the same shelf. Twenty-nine are herbal stimulant laxatives, aloe latex and cascara sagrada among them, and doubling up on laxatives can drain fluid and potassium fast.”

Reviewed by 2 · Jul 18, 2026

Open the Magnesium Hydroxide (OTC drug) interaction page

One more smart check

Taking Manna as Part of a Dietary Supplement Product? Check It for Interactions

We hold 27 real supplement products containing Manna, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Manna. Your product may carry other ingredients that interact with Magnesium Hydroxide (OTC drug) too, on top of Manna — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Manna and Magnesium Hydroxide (OTC drug) Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Manna
Top half

#692 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Magnesium Hydroxide (OTC drug)
Steady interest

#1,574 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Manna

What is Manna?

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

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.

Read the full Manna monograph & all interactions
Keep checking

Other Drugs & Manna

Browse every other medication we’ve checked against Manna — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
98Moderate
0Minor
2,731No known interaction
98 Moderate 2,731 No interaction
Moderate

98 interactions

Showing 60 of 98 moderate interactions — see all 98 on the Manna page.

No interaction 2,731 drugs checked — show the list

We also checked Manna against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,731 medications checked with no known interaction — see the full Manna list.

See the full Manna interactions page
See every supplement checked against Magnesium Hydroxide (OTC drug), ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

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.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Manna monograph › Uses, safety, and every drug interaction in one place Magnesium Hydroxide (OTC drug) supplement interactions › Every supplement checked against Magnesium Hydroxide (OTC drug), ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Manna and Magnesium Hydroxide (OTC drug) Together: Common Questions

Can you take Manna with Magnesium Hydroxide (OTC drug)?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Manna and Magnesium Hydroxide (OTC drug) interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

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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.