Drug & supplement interaction

Khat + Olanzapine

Olanzapine brand name: Zyprexa.

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

Khat has a moderate interaction with Olanzapine. Khat may affect response to antipsychotic treatment.

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

Khat and Olanzapine

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

Moderate

ANTIPSYCHOTIC DRUGS

Why this applies to Olanzapine

Olanzapine falls under ANTIPSYCHOTIC DRUGS — the group Khat interacts with.

Khat may affect response to antipsychotic treatment. In a large retrospective study of adults with newly diagnosed schizophrenia, chewing khat was associated with a decreased retention rate with the initial antipsychotic agent when compared with non-chewers, and lack of efficacy was the most commonly reported reason for switching antipsychotic agents among khat users. Until more is known, avoid khat in patients taking antipsychotic agents.
Severity Moderate Likelihood Possible Evidence B

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 is the simple version: olanzapine (Zyprexa) is there to calm down the brain signaling that drives symptoms like disordered thinking, agitation, or mood swings. Khat does the opposite. Its main ingredient, cathinone, acts a lot like amphetamine and revs up dopamine and norepinephrine. So you have one substance trying to settle things down while the other winds them up, and they can work against each other.

A large real-world study of people newly started on antipsychotics found that khat chewers were more likely to switch medications, usually because the drug just was not working well enough. In plain terms, khat may blunt how well your olanzapine controls your symptoms. Keep in mind khat is also illegal in the US. Please talk with your doctor or pharmacist before making any changes, and do not stop your olanzapine on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Hakami T, Mahmoud M, Mohammed B, El-Setouhy M. Effects of khat use on response to antipsychotic medications in patients with newly diagnosed schizophrenia: a retrospective study. East Mediterr Health J 2021;27(4):353-360. 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 Olanzapine 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. Olanzapine)
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.

From our Q&A

Questions About Khat or Olanzapine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Khat or Olanzapine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Olanzapine

This page covers Khat only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Olanzapine page lists 160 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Indian Snakeroot (major), Lithium (major), Rauvolfia Vomitoria (major) and 1,3-dmaa (moderate).

By severity: 4 major · 118 moderate · 38 minor.

From our pharmacist’s overview on the Olanzapine page

“Olanzapine (Zyprexa) is an antipsychotic prescribed for schizophrenia and bipolar disorder, and adding supplements to it warrants genuine care. Four of the 160 ingredients on file rate major, and those four deserve your attention before anything else: lithium supplements raise the risk of serotonin syndrome, activated charcoal can trap…”

Reviewed by 2 · Jul 18, 2026

Open the Olanzapine interaction page

How much people look this up

Where Khat and Olanzapine 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

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

29 days ago today
Medication Olanzapine
Steady interest

#1,685 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
Medication

About Olanzapine

What Is Olanzapine Used For?

Brand name: Zyprexa

Olanzapine treats schizophrenia and the manic or mixed episodes of bipolar I disorder in both adults and adolescents (ages 13–17). It can also be used alongside valproate or lithium to treat manic or mixed episodes in adults. When combined with fluoxetine, olanzapine tablets and orally disintegrating tablets are used to treat depressive episodes associated with bipolar I disorder and treatment-resistant depression in adults.

Olanzapine intramuscular injection (short-acting) is used by healthcare providers to quickly calm acute agitation in adults with schizophrenia or bipolar I mania. Zyprexa Relprevv — a separate, long-acting intramuscular formulation available only through a restricted program — is indicated specifically for the treatment of schizophrenia in adults.

See full Olanzapine drug information
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 Olanzapine, 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
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Pharmacist Counseling Corner

Taking Khat and Olanzapine Together: Common Questions

Can you take Khat with Olanzapine?
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 Olanzapine 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 Olanzapine 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.