Drug & supplement interaction

Bitter Orange + Bisoprolol, Hydrochlorothiazide

Bisoprolol, Hydrochlorothiazide brand name: Ziac.

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

Bitter Orange has a minor interaction with Bisoprolol, Hydrochlorothiazide. Theoretically, bitter orange might increase levels of drug metabolized by CYP2D6.

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Bitter Orange and Bisoprolol, Hydrochlorothiazide

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

Minor

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

Why this applies to Bisoprolol, Hydrochlorothiazide

Bisoprolol, Hydrochlorothiazide falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Bitter Orange interacts with.

Theoretically, bitter orange might increase levels of drug metabolized by CYP2D6.
In vitro research shows that octopamine, a constituent of bitter orange, weakly inhibits CYP2D6 enzymes. This effect has not been reported in humans.
Severity Minor 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

Ziac combines bisoprolol, a beta-blocker that helps slow your heart and lower blood pressure, with hydrochlorothiazide, a water pill. The bisoprolol part is partly handled by a liver enzyme called CYP2D6. On paper, a compound in bitter orange (octopamine) might weakly block that enzyme, which could let bisoprolol levels creep up a bit. If that happened, you might notice things like a slower heart rate, more tiredness, dizziness, or lightheadedness when you stand.

Here's the bigger picture, though: this enzyme effect was only seen in lab dishes, never confirmed in people, and it's rated minor. My real concern is the opposite tug-of-war. Bitter orange is a stimulant that can raise heart rate and blood pressure, working against what Ziac is trying to do. I'd run any bitter orange product past your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu Y, Santillo MF. Cytochrome P450 2D6 and 3A4 enzyme inhibition by amine stimulants in dietary supplements. Drug Test Anal. 2016;8(3-4):307-10. PubMed

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

Bitter Orange Also Interacts With Other Medications

Bitter Orange has 10 major, 876 moderate, 70 minor known drug interactions in our database — the Bisoprolol, Hydrochlorothiazide one above is one of them. If you take anything else, check it against the full list below.

Major 10 Moderate 876 Minor 70 No known interaction 1,874 (incl. Bisoprolol, Hydrochlorothiazide)
Taking anything else?

Check Another of Your Medications Against Bitter Orange

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

Everything else you take

See Every Supplement That Interacts With Bisoprolol, Hydrochlorothiazide

This page covers Bitter Orange only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Bisoprolol, Hydrochlorothiazide page lists 276 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), Asarabacca (major) and Dolomite (major).

By severity: 11 major · 234 moderate · 31 minor.

From our pharmacist’s overview on the Bisoprolol, Hydrochlorothiazide page

“This is one of the supplement lists I would read closely before adding anything alongside bisoprolol and hydrochlorothiazide (Ziac). The combination already lowers blood pressure two ways, and most of these interactions push on those same levers, either dropping pressure further or acting like extra diuretics that compound potassium an…”

Reviewed by 2 · Jul 18, 2026

Open the Bisoprolol, Hydrochlorothiazide interaction page

One more smart check

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

We hold 1,000 real supplement products containing Bitter Orange, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bitter Orange. Your product may carry other ingredients that interact with Bisoprolol, Hydrochlorothiazide too, on top of Bitter Orange — 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 Bitter Orange and Bisoprolol, Hydrochlorothiazide 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 Bitter Orange
Top 25%

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

29 days ago today
Medication Bisoprolol, Hydrochlorothiazide
Top 25%

#684 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 Bitter Orange

What is Bitter Orange?

Bitter Orange
  • Weight loss
  • Athletic performance and energy
  • Digestive upset
  • Appetite control
  • Aromatherapy for stress (neroli oil)

Bitter orange is a citrus fruit whose extracts contain synephrine, a mild stimulant often added to weight-loss and energy supplements. Evidence that it works for weight loss or performance is limited, and because it can raise heart rate and blood pressure, people with heart problems, high blood pressure, or who are pregnant should avoid it. Talk to your pharmacist or doctor before using it, especially if you take other stimulants.

Read the full Bitter Orange monograph & all interactions
Keep checking

Other Drugs & Bitter Orange

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

10Major
876Moderate
70Minor
1,873No known interaction
10 Major 876 Moderate 70 Minor 1,873 No interaction
Major

10 interactions

Moderate

876 interactions

Showing 60 of 876 moderate interactions — see all 876 on the Bitter Orange page.

Minor

70 interactions

Showing 60 of 70 minor interactions — see all 70 on the Bitter Orange page.

No interaction 1,873 drugs checked — show the list

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

Showing the 60 most looked-up of 1,873 medications checked with no known interaction — see the full Bitter Orange list.

See the full Bitter Orange interactions page
See every supplement checked against Bisoprolol, Hydrochlorothiazide, 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
Bitter Orange monograph › Uses, safety, and every drug interaction in one place Bisoprolol, Hydrochlorothiazide supplement interactions › Every supplement checked against Bisoprolol, Hydrochlorothiazide, 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 Bitter Orange and Bisoprolol, Hydrochlorothiazide Together: Common Questions

Can you take Bitter Orange with Bisoprolol, Hydrochlorothiazide?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Bitter Orange and Bisoprolol, Hydrochlorothiazide interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Bisoprolol, Hydrochlorothiazide and Bitter Orange?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.