Drug & supplement interaction

Docosahexaenoic Acid (dha) + Mannitol

Mannitol brand names: Osmitrol, Bronchitol.

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

Docosahexaenoic Acid (dha) has a moderate interaction with Mannitol. Theoretically, taking DHA with antihypertensive drugs might increase the risk of hypotension.

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

Docosahexaenoic Acid (dha) and Mannitol

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Mannitol

Mannitol falls under ANTIHYPERTENSIVE DRUGS — the group Docosahexaenoic Acid (dha) interacts with.

Theoretically, taking DHA with antihypertensive drugs might increase the risk of hypotension.
Fish oils containing DHA can lower blood pressure and might have additive effects in patients treated with antihypertensives; use with caution.
Severity Moderate Likelihood Probable Evidence B

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..

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

Here's the gist: DHA (an omega-3 from fish oil) can gently nudge your blood pressure down on its own. When you pair it with something that also lowers blood pressure, those effects can stack up. Our database groups mannitol under blood pressure lowering drugs for this interaction.

In real life, mannitol is mainly used in hospital or clinic settings, as an IV to reduce pressure in the brain or eyes and pull off extra fluid, or as an inhaled powder (Bronchitol) for cystic fibrosis. Because it removes fluid, it can lower blood pressure too. Adding DHA could mean a slightly bigger drop, leaving you feeling lightheaded or dizzy. This is mostly theoretical and based on weaker evidence, so don't panic. Just mention your fish oil to your care team so they can keep an eye on things.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Prisco D, Paniccia R, Bandinelli B, et al. Effect of medium-term supplementation with a moderate dose of n-3 polyunsaturated fatty acids on blood pressure in mild hypertensive patients. Thromb Res 1998;1:105-12.
  2. Toft I, Bonaa KH, Ingebretsen OC, et al. Effects of n-3 polyunsaturated fatty acids on glucose homeostasis and blood pressure in essential hypertension. A randomized, controlled trial. Ann Intern Med 1995;123:911-8.
  3. Sacks FM, Hebert P, Appel LJ, et al. Short report: the effect of fish oil on blood pressure and high-density lipoprotein-cholesterol levels in phase I of the trials of hypertension prevention. J Hypertens 1994;12:209-13.
  4. Vandongen R, Mori TA, Burke V, et al. Effects on blood pressure of omega 3 fats in subjects at increased risk of cardiovascular disease. Hypertension 1993;22:371-9. PubMed
  5. Mori, T. A., Bao, D. Q., Burke, V., Puddey, I. B., and Beilin, L. J. Docosahexaenoic acid but not eicosapentaenoic acid lowers ambulatory blood pressure and heart rate in humans. Hypertension 1999;34(2):253-260. PubMed
  6. Nestel, P., Shige, H., Pomeroy, S., Cehun, M., Abbey, M., and Raederstorff, D. The n-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid increase systemic arterial compliance in humans. Am.J.Clin.Nutr. 2002;76(2):326-330. PubMed
  7. Woodman, R. J., Mori, T. A., Burke, V., Puddey, I. B., Barden, A., Watts, G. F., and Beilin, L. J. Effects of purified eicosapentaenoic acid and docosahexaenoic acid on platelet, fibrinolytic and vascular function in hypertensive type 2 diabetic patients PubMed
  8. Theobald, H. E., Goodall, A. H., Sattar, N., Talbot, D. C., Chowienczyk, P. J., and Sanders, T. A. Low-dose docosahexaenoic acid lowers diastolic blood pressure in middle-aged men and women. J Nutr 2007;137(4):973-978.

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

Docosahexaenoic Acid (dha) Also Interacts With Other Medications

Docosahexaenoic Acid (dha) has 374 moderate known drug interactions in our database — the Mannitol one above is one of them. If you take anything else, check it against the full list below.

Moderate 374 No known interaction 2,456 (incl. Mannitol)
Taking anything else?

Check Another of Your Medications Against Docosahexaenoic Acid (dha)

Covers the 2,830 medications we’ve checked against Docosahexaenoic Acid (dha). Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Mannitol

This page covers Docosahexaenoic Acid (dha) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mannitol page lists 200 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Lithium (major) and Oleander (major).

By severity: 7 major · 169 moderate · 24 minor.

From our pharmacist’s overview on the Mannitol page

“American hellebore tops my worry list for anyone on mannitol (Osmitrol, Bronchitol), an osmotic diuretic used to draw fluid off the brain or, when inhaled, to clear mucus in cystic fibrosis. The plant's alkaloids drop blood pressure and slow the heart, a dangerous match for a drug that already shifts fluid and pressure quickly.”

Reviewed by 2 · Jul 18, 2026

Open the Mannitol interaction page

How much people look this up

Where Docosahexaenoic Acid (dha) and Mannitol 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 Docosahexaenoic Acid (dha)
Steady interest

#1,218 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Mannitol
Top 25%

#377 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 Docosahexaenoic Acid (dha)

What is Docosahexaenoic Acid (dha)?

Docosahexaenoic Acid (dha)
  • Brain and cognitive health
  • Eye and vision health
  • Fetal and infant development
  • Heart and triglyceride support
  • General omega-3 supplementation

DHA is an omega-3 fatty acid found in fatty fish and algae that is a building block for the brain, nervous system, and eyes. It is widely used and generally well tolerated, with the strongest support for fetal/infant development and lowering triglycerides; evidence for many other uses is mixed. Talk with your pharmacist or doctor before starting, especially if you are pregnant, have a bleeding risk, or take blood thinners.

Read the full Docosahexaenoic Acid (dha) monograph & all interactions
Keep checking

Other Drugs & Docosahexaenoic Acid (dha)

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

0Major
374Moderate
0Minor
2,455No known interaction
374 Moderate 2,455 No interaction
Moderate

374 interactions

Showing 60 of 374 moderate interactions — see all 374 on the Docosahexaenoic Acid (dha) page.

No interaction 2,455 drugs checked — show the list

We also checked Docosahexaenoic Acid (dha) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,455 medications checked with no known interaction — see the full Docosahexaenoic Acid (dha) list.

See the full Docosahexaenoic Acid (dha) interactions page
See every supplement checked against Mannitol, 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
Docosahexaenoic Acid (dha) monograph › Uses, safety, and every drug interaction in one place Mannitol supplement interactions › Every supplement checked against Mannitol, 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 Docosahexaenoic Acid (dha) and Mannitol Together: Common Questions

Can you take Docosahexaenoic Acid (dha) with Mannitol?
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 Docosahexaenoic Acid (dha) and Mannitol 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

Still Have a Question About Mannitol and Docosahexaenoic Acid (dha)?

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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.