Dong Quai and Midazolam Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Midazolam Injection
Dong Quai
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
Excessive muscle relaxation and central nervous system depression
Interaction Deep Dive
Dong quai extract inhibited metabolism of diazepam and increased its muscle relaxant effect in rats1. The effect of dong quai on the metabolism of diazepam and other benzodiazepines in humans is unknown, as the dose used in the animal study (1 gram/kilogram) is higher than that usually used in humans. Theoretically, if dong quai similarly affects the pharmacokinetics of benzodiazepines in humans, increased levels of benzodiazepine may occur which may result in greater pharmacologic effect of the benzodiazepine. Furocoumarins in dong quai may be responsible for inhibition of hepatic drug metabolism through inhibition of CYP2C11- and CYP2D1-mediated demethylation, CYP3A2-mediated hydroxylation, and CYP2D1-mediated 4'-hydroxylation of diazepam 1.It is suspected that dong quai may affect other drugs metabolized by the cytochrome P450 enzymes which metabolize diazepam. Caution is advised.
Why it happens (mechanism)
Inhibition of hepatic cytochrome P450 enzyme metabolism of benzodiazepines
Literature reports
2 reports — tap to read
a) Angelica dahurica (dong quai) extract 1 gram/kilogram orally increased the maximum concentration of oral diazepam, yet did not alter pharmacokinetics of intravenous (IV) diazepam in rats. Diazepam 5 milligrams/kilogram (mg/kg) was administered orally to rats alone, and one hour after dong quai extract. When administered alone, only the maximum concentration (Cmax) of diazepam could be calculated, as the plasma concentration of diazepam was undetectable at all sample time points except for 2 hours. After dong quai, diazepam Cmax increased from 23.0 +/- 12.4 nanograms/milliliter (ng/mL) to 92.1 +/- 50.3 ng/mL (p less than 0.05). Diazepam pharmacokinetics were not significantly changed by dong quai when diazepam was administered intravenously. Diazepam is metabolized by CYP2C11- and CYP2D1-mediated demethylation, CYP3A2-mediated hydroxylation, and CYP2D1-mediated 4'-hydroxylation. Dong quai extract inhibited all of these isoenzymes 1.
b) Angelica dahurica (dong quai) extract 1 gram/kilogram orally significantly increased the muscle relaxant effect of diazepam (5 mg/kg IV) in rats. Duration of rotarod disruption was increased with high-dose oral dong quai (1 gram/kg) versus diazepam alone (p less than 0.05). Low-dose oral dong quai (0.3 grams/kg) had no effect on rotarod performance when administered with diazepam 5 mg/kg IV. Dong quai administered alone had no effect on rotarod performance 1.
Common questions
Can I take Dong Quai and Midazolam Injection together?
Excessive muscle relaxation and central nervous system depression Always confirm with your pharmacist or prescriber before making any change.
How serious is the Dong Quai and Midazolam Injection 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Dong Quai or Midazolam Injection 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)
- Ishihara K, Kushida J, Yuzurihara M, et al: Interaction of drugs and Chinese herbs: pharmacokinetic changes of tolbutamide and diazepam caused by extract of Angelica dahurica. J Pharm Pharmacol 2000; 52(8):1023-1029.
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