Drug & supplement interaction

Khat + Promethazine, Pseudoephedrine

Promethazine, Pseudoephedrine brand name: Phenergan D.

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

Khat has a moderate interaction with Promethazine, Pseudoephedrine. Cathinone, a constituent of khat, appears to have sympathomimetic effects and can increase blood pressure and heart rate.

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

Khat and Promethazine, Pseudoephedrine

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

Moderate

STIMULANT DRUGS

Why this applies to Promethazine, Pseudoephedrine

Promethazine, Pseudoephedrine falls under STIMULANT DRUGS — the group Khat interacts with.

Cathinone, a constituent of khat, appears to have sympathomimetic effects and can increase blood pressure and heart rate. Theoretically, combining khat with other central nervous system (CNS) stimulant drugs might increase the risk of cardiovascular toxicity. Some CNS stimulants include nicotine, cocaine, sympathomimetic amines, and amphetamines.
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

The part of Phenergan D to focus on here is the pseudoephedrine, which is a decongestant that mildly stimulates the body, much like khat does. Khat's main ingredient, cathinone, works in an amphetamine-like way that can push up your blood pressure and heart rate. Stacking two stimulant-type substances together could add up, so you might notice a racing or pounding heart, jitteriness, headache, or higher blood pressure.

To be fair, this is a theoretical concern based on how these chemicals act, not from solid human studies. Khat is also a controlled, illegal substance in the U.S. and isn't safe to use. If you have any worries about your decongestant and your heart, please check with your pharmacist or doctor before making changes.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Brenneisen, R., Fisch, H. U., Koelbing, U., Geisshusler, S., and Kalix, P. Amphetamine-like effects in humans of the khat alkaloid cathinone. Br.J.Clin.Pharmacol. 1990;30(6):825-828. 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

Khat Also Interacts With Other Medications

Khat has 4 major, 400 moderate known drug interactions in our database — the Promethazine, Pseudoephedrine one above is one of them. If you take anything else, check it against the full list below.

Major 4 Moderate 400 No known interaction 2,426 (incl. Promethazine, Pseudoephedrine)
Taking anything else?

Check Another of Your Medications Against Khat

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

Everything else you take

See Every Supplement That Interacts With Promethazine, Pseudoephedrine

This page covers Khat only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Promethazine, Pseudoephedrine page lists 116 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Henbane (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 7 major · 93 moderate · 16 minor.

From our pharmacist’s overview on the Promethazine, Pseudoephedrine page

“Phenergan D combines a sedating antihistamine, promethazine, with the decongestant stimulant pseudoephedrine, and its supplement list pulls hard in both directions, so this is one to treat with genuine care. The biggest cluster, from everyday caffeine sources like coffee and cola nut up to ephedra, stacks extra stimulation on the pseud…”

Reviewed by 2 · Jul 18, 2026

Open the Promethazine, Pseudoephedrine interaction page

How much people look this up

Where Khat and Promethazine, Pseudoephedrine 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 Khat
Top half

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

29 days ago today
Medication Promethazine, Pseudoephedrine
Top 25%

#467 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 Khat

What is Khat?

Khat
  • Stimulant for energy and alertness
  • Euphoria and mood elevation
  • Reducing fatigue
  • Appetite suppression
  • Social and traditional ceremonies

Khat is a plant chewed for its amphetamine-like stimulant effects, but it carries serious risks including high blood pressure, heart problems, mental health effects, and dependence. It is a controlled substance and illegal in the United States and many other countries, so it should not be used.

Read the full Khat monograph & all interactions
Keep checking

Other Drugs & Khat

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

4Major
400Moderate
0Minor
2,425No known interaction
4 Major 400 Moderate 2,425 No interaction
Major

4 interactions

Moderate

400 interactions

Showing 60 of 400 moderate interactions — see all 400 on the Khat page.

No interaction 2,425 drugs checked — show the list

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

Showing the 60 most looked-up of 2,425 medications checked with no known interaction — see the full Khat list.

See the full Khat interactions page
See every supplement checked against Promethazine, Pseudoephedrine, 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
Khat monograph › Uses, safety, and every drug interaction in one place Promethazine, Pseudoephedrine supplement interactions › Every supplement checked against Promethazine, Pseudoephedrine, 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 Khat and Promethazine, Pseudoephedrine Together: Common Questions

Can you take Khat with Promethazine, Pseudoephedrine?
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 Khat and Promethazine, Pseudoephedrine 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 Promethazine, Pseudoephedrine and Khat?

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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.