Drug & supplement interaction

Malic Acid + Phenoxybenzamine

Phenoxybenzamine brand name: Dibenzyline.

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

Malic Acid has a moderate interaction with Phenoxybenzamine. Theoretically, malic acid might increase the risk of hypotension when taken with antihypertensive drugs.

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

Malic Acid and Phenoxybenzamine

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Phenoxybenzamine

Phenoxybenzamine falls under ANTIHYPERTENSIVE DRUGS — the group Malic Acid interacts with.

Theoretically, malic acid might increase the risk of hypotension when taken with antihypertensive drugs.
Animal research shows that malic acid isolated from tagetes roots can reduce mean arterial blood pressure.
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 gist: phenoxybenzamine already lowers your blood pressure by blocking alpha receptors, which relaxes your blood vessels. The thinking is that malic acid might nudge your blood pressure down a little too, so stacking the two could add up and leave you feeling lightheaded, dizzy, or faint, especially when you stand up quickly. Phenoxybenzamine is well known for causing that kind of drop, plus a fast heartbeat and stuffy nose.

That said, this is theoretical and based only on animal research, not real cases in people. Food amounts of malic acid (like in apples) are very unlikely to matter. Before starting a concentrated supplement, just check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Saleem R, Ahmad M, Naz A, et al. Hypotensive and toxicological study of citric acid and other constituents from Tagetes patula roots. Arch Pharm Res 2004;27(10):1037-42.

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

Malic Acid Also Interacts With Other Medications

Malic Acid has 171 moderate known drug interactions in our database — the Phenoxybenzamine one above is one of them. If you take anything else, check it against the full list below.

Moderate 171 No known interaction 2,659 (incl. Phenoxybenzamine)
Taking anything else?

Check Another of Your Medications Against Malic Acid

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

Everything else you take

See Every Supplement That Interacts With Phenoxybenzamine

This page covers Malic Acid only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenoxybenzamine page lists 137 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), Tyramine (major) and Adrafinil (moderate).

By severity: 4 major · 112 moderate · 21 minor.

From our pharmacist’s overview on the Phenoxybenzamine page

“Phenoxybenzamine (Dibenzyline) is usually prescribed for pheochromocytoma, an adrenal tumor that sends blood pressure surging, often to steady a patient in the weeks before surgery, so keeping pressure in a narrow band is the entire goal of treatment. That makes this a list to treat carefully rather than skim.”

Reviewed by 2 · Jul 18, 2026

Open the Phenoxybenzamine interaction page

One more smart check

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

We hold 678 real supplement products containing Malic Acid, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Malic Acid. Your product may carry other ingredients that interact with Phenoxybenzamine too, on top of Malic Acid — 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 Malic Acid and Phenoxybenzamine 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 Malic Acid
Top 25%

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

29 days ago today
Medication Phenoxybenzamine
Top half

#740 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 Malic Acid

What is Malic Acid?

Malic Acid
  • Fibromyalgia symptoms
  • Muscle pain and fatigue
  • Dry mouth (used in some lozenges)
  • Skin exfoliation (topical)
  • Flavoring and food additive

Malic acid is a natural acid found in apples and other fruits, often combined with magnesium in supplements marketed for fibromyalgia and muscle pain. The evidence for its health benefits is weak and limited, and it is mostly used as a food flavoring. It is generally well tolerated in food amounts, but talk to your pharmacist or doctor before using supplement doses.

Read the full Malic Acid monograph & all interactions
Medication

About Phenoxybenzamine

What Is Phenoxybenzamine Used For?

Brand name: Dibenzyline

Phenoxybenzamine hydrochloride capsules are used to treat pheochromocytoma — a rare tumor of the adrenal gland that releases large bursts of stress hormones, causing dangerous spikes in blood pressure and heavy sweating. The capsules help keep those episodes under control.

If the heart rate becomes too fast during treatment, a doctor may also prescribe a beta-blocker alongside phenoxybenzamine.

See full Phenoxybenzamine drug information
Keep checking

Other Drugs & Malic Acid

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

0Major
171Moderate
0Minor
2,658No known interaction
171 Moderate 2,658 No interaction
Moderate

171 interactions

Showing 60 of 171 moderate interactions — see all 171 on the Malic Acid page.

No interaction 2,658 drugs checked — show the list

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

Showing the 60 most looked-up of 2,658 medications checked with no known interaction — see the full Malic Acid list.

See the full Malic Acid interactions page
See every supplement checked against Phenoxybenzamine, 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
Malic Acid monograph › Uses, safety, and every drug interaction in one place Phenoxybenzamine supplement interactions › Every supplement checked against Phenoxybenzamine, ranked by severity Phenoxybenzamine drug information › The full plain-English guide to this medication 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 Malic Acid and Phenoxybenzamine Together: Common Questions

Can you take Malic Acid with Phenoxybenzamine?
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 Malic Acid and Phenoxybenzamine 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 Phenoxybenzamine and Malic Acid?

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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.