Khat and Amoxicillin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amoxicillin
Khat
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced effectiveness of amoxicillin
Interaction Deep Dive
Khat chewing significantly reduced the extent of amoxicillin urinary excretion in 8 healthy subjects when amoxicillin was taken midway through a four hour khat chewing session, but not at other administration times1.
Why it happens (mechanism)
Reduced absorption of amoxicillin speculated to result from formation of insoluble, unabsorbable complexes between the tannin content of khat and amoxicillin
Literature reports
1 report — tap to read
a) Khat chewing significantly reduced the percentage excreted unchanged and maximum peak excretion in urine of amoxicillin in 8 healthy male subjects in a crossover study. A single dose of amoxicillin 500 milligrams was taken orally in 5 conditions with a washout period of 7 days between each condition: (A) alone under fasting conditions, (B) just before khat chewing, (C) just before khat chewing with regular food and drink, (D) 2 hours before khat chewing, (E) midway through the 4 hour khat chewing session, and (F) 2 hours after the end of the khat chewing session. Khat ('Sauty') was obtained from a local market in Yemen. Urine measures of excretion were used to estimate bioavailability; urine was collected at 0, 1, 2, 3, 4, 5, 6, 7, 8, and 12 hours after the amoxicillin dose. Percentage excreted unchanged and maximum peak excretion in urine were significantly reduced only in condition E, while maximum time to reach the peak excretion was unchanged (p less than 0.02) 1.
Common questions
Can I take Khat and Amoxicillin together?
Reduced effectiveness of amoxicillin Always confirm with your pharmacist or prescriber before making any change.
How serious is the Khat and Amoxicillin interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Khat or Amoxicillin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Attef OA, Ali AA, & Hassan MA: Effect of khat chewing on the bioavailability of ampicillin and amoxycillin. J Antimicrob Chemother 1997; 39)4):523-525. PubMed
Keep reading about Amoxicillin
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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