Drug & supplement interaction

White Pepper + Haloperidol

Haloperidol brand name: Haldol.

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

Haloperidol falls into 2 drug categories that White Pepper can interact with; the most serious is rated moderate. In vitro evidence suggests that some constituents of white pepper inhibit cytochrome P450 2D6 (CYP2D6).

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

White Pepper and Haloperidol

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

White Pepper interacts with whole categories of medication. Haloperidol falls into 2 of those categories, so it can interact with White Pepper in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

1 of 2

Why this applies to Haloperidol

Haloperidol falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group White Pepper interacts with.

In vitro evidence suggests that some constituents of white pepper inhibit cytochrome P450 2D6 (CYP2D6). Theoretically, concomitant use may affect drugs metabolized by CYP2D6.
Some drugs metabolized by CYP2D6 include amitriptyline (Elavil), codeine, desipramine (Norpramin), flecainide (Tambocor), haloperidol (Haldol), imipramine (Tofranil), metoprolol (Lopressor, Toprol XL), ondansetron (Zofran), paroxetine (Paxil), risperidone (Risperdal), tramadol (Ultram), venlafaxine (Effexor), and others.
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

Your body uses a liver enzyme called CYP2D6 to help break down haloperidol (Haldol). Lab studies suggest that piperine, the spicy compound in white pepper, can slow that enzyme down a bit. In theory, if that enzyme works more slowly, haloperidol could clear out of your system less efficiently and build up a little. That could mean stronger effects and a higher chance of side effects like drowsiness, stiffness, restlessness, tremor, or muscle movements you cannot control.

Here's the reassuring part: this is based only on test-tube research, not on real people, and the amount of pepper you sprinkle on food is very unlikely to cause a problem. Concentrated piperine supplements are a different story. Before starting any pepper or piperine supplement, just check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Subehan, Usia, T., Kadota, S., and Tezuka, Y. Mechanism-based inhibition of human liver microsomal cytochrome P450 2D6 (CYP2D6) by alkamides of Piper nigrum. Planta Med 2006;72(6):527-532.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

Haloperidol also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

In vitro evidence suggests that piperine, a constituent of white pepper, inhibits cytochrome P450 3A4 (CYP3A4). Theoretically, concomitant use with white pepper might increase the effects and side effects of drugs metabolized by CYP3A4.
Some drugs metabolized by CYP3A4 include some calcium channel blockers (diltiazem, nicardipine, verapamil), chemotherapeutic agents (etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), glucocorticoids, cisapride (Propulsid), alfentanil (Alfenta), fentanyl (Sublimaze), losartan (Cozaar), fluoxetine (Prozac), midazolam (Versed), omeprazole (Prilosec), ondansetron (Zofran), propranolol (Inderal), fexofenadine (Allegra), and numerous others.
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 for Haloperidol (Haldol): your liver uses an enzyme called CYP3A4 (among others) to help break this medication down. Piperine, the spicy compound in white pepper, has shown in lab dish studies that it can slow that same enzyme. If CYP3A4 is slowed, haloperidol could clear a little more slowly and build up, which in theory might mean stronger effects or more side effects like drowsiness, dizziness, muscle stiffness, restlessness, or those involuntary movements haloperidol can cause.

That said, this is theoretical, based only on test-tube data, not real patients. Normal cooking amounts of white pepper on your food are very unlikely to cause trouble. Concentrated piperine supplements are the bigger question, so check with your pharmacist or doctor before using those.

Contact Dr. Brian directly if you have additional questions on this interaction

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

White Pepper Also Interacts With Other Medications

White Pepper has 975 moderate, 3 minor known drug interactions in our database — the Haloperidol one above is among them. If you take anything else, check it against the full list below.

Moderate 975 Minor 3 No known interaction 1,852 (incl. Haloperidol)
Taking anything else?

Check Another of Your Medications Against White Pepper

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

Everything else you take

See Every Supplement That Interacts With Haloperidol

This page covers White Pepper only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Haloperidol page lists 211 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 11 major · 157 moderate · 43 minor.

From our pharmacist’s overview on the Haloperidol page

“Haloperidol (Haldol) is a potent antipsychotic prescribed for schizophrenia and severe agitation, and the 211 supplements on this list warrant genuine care, starting with the 11 rated major. Most of the trouble runs through the liver enzymes that clear haloperidol from the body.”

Reviewed by 2 · Jul 18, 2026

Open the Haloperidol interaction page

One more smart check

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

We hold 2 real supplement products containing White Pepper, each one broken down to its full ingredient list — and combination products often carry several ingredients besides White Pepper. Your product may carry other ingredients that interact with Haloperidol too, on top of White Pepper — 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 White Pepper and Haloperidol 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 White Pepper
Steady interest

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

29 days ago today
Medication Haloperidol
Steady interest

#1,850 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 White Pepper

What is White Pepper?

  • Digestive upset
  • Seasoning and appetite support
  • Cough and cold remedies (traditional)
  • Minor aches and pains (traditional)
  • Antimicrobial (traditional)

White pepper comes from the same plant as black pepper and is mostly used as a kitchen spice. In normal food amounts it is generally safe for most people, but there is little solid human research supporting its use as a medicine. Talk with your pharmacist or doctor before using concentrated supplements, especially if you are pregnant, breastfeeding, or have a health condition.

Read the full White Pepper monograph & all interactions
Medication

About Haloperidol

What Is Haloperidol Used For?

Brand name: Haldol

Haloperidol is used to manage symptoms of psychotic disorders and to control the tics and vocal outbursts of Tourette's disorder in both children and adults.

In children, it is also used for severe combative or explosive behavior problems, and for hyperactivity with conduct disorders — but only when other treatments like therapy or non-antipsychotic medications have not worked.

See full Haloperidol drug information
Keep checking

Other Drugs & White Pepper

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

0Major
975Moderate
3Minor
1,851No known interaction
975 Moderate 3 Minor 1,851 No interaction
Moderate

975 interactions

Showing 60 of 975 moderate interactions — see all 975 on the White Pepper page.

Minor

3 interactions

No interaction 1,851 drugs checked — show the list

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

Showing the 60 most looked-up of 1,851 medications checked with no known interaction — see the full White Pepper list.

See the full White Pepper interactions page
See every supplement checked against Haloperidol, 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
White Pepper monograph › Uses, safety, and every drug interaction in one place Haloperidol supplement interactions › Every supplement checked against Haloperidol, ranked by severity Haloperidol 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 White Pepper and Haloperidol Together: Common Questions

Can you take White Pepper with Haloperidol?
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.
Why are there 2 interactions listed for White Pepper and Haloperidol?
Haloperidol belongs to more than one drug category, and White Pepper interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the White Pepper and Haloperidol 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 Haloperidol and White Pepper?

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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.