What are the documented clinical case reports of CBD causing adverse events in patients on DOACs, if any, since 2023?
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Executive summary
A targeted review of the supplied literature finds no published clinical case reports since 2023 that directly document cannabidiol (CBD) causing an adverse event specifically in a patient taking a direct oral anticoagulant (DOAC) (e.g., apixaban, rivaroxaban, edoxaban, dabigatran) within the materials provided [1] [2]. The literature does, however, repeatedly flag a plausible pharmacokinetic risk—CBD’s inhibition of cytochrome P450 enzymes and interactions with transporters such as P‑glycoprotein—which could theoretically alter DOAC exposure and bleeding risk, and regulatory adverse‑event databases contain CBD reports though not DOAC‑linked case reports in these sources [3] [4] [2].
1. Absence of documented CBD–DOAC case reports in the supplied reviews and surveillance analyses
Comprehensive literature syntheses and case‑report searches supplied here included a PubMed‑based compilation of cannabis–drug interaction case reports through July 2023 and analyses of FDA adverse event reporting; neither the systematic review of published case reports nor the FDA surveillance analysis in the provided sources identifies a published clinical case report explicitly tying CBD to an adverse outcome in a patient on a DOAC [1] [2]. The AJPH analysis of FDA hemp product adverse event cases from 2019–2023 reported 253 CBD‑involved cases overall but did not single out DOAC co‑use as a documented series of case reports in the available extract [2].
2. Mechanistic plausibility: why clinicians worry about CBD + DOACs even without case reports
The pharmacology literature supplied documents that CBD modulates major drug‑metabolizing pathways—most notably CYP3A4 and CYP2C19—and affects transporters like P‑glycoprotein, creating a credible mechanism for pharmacokinetic drug‑drug interactions that could increase or decrease plasma concentrations of concomitant medicines [3] [4]. Because most DOACs are substrates of CYP3A4 and/or P‑glycoprotein, these mechanistic data create a well‑founded theoretical risk that CBD could alter DOAC exposure and thereby change bleeding or thrombotic risk, even if concrete clinical case reports are not present in the supplied sources [4] [3].
3. Signals in trials and adverse‑event databases — general CBD harms but not DOAC‑specific events
Randomized trials and meta‑analyses have documented CBD‑associated adverse events such as elevated transaminases, somnolence, diarrhea and sedation, and regulatory systems have accumulated hundreds of CBD‑involved reports to the FDA, but the supplied trial and surveillance data highlight these general safety concerns rather than establishing CBD as a documented precipitant of DOAC failure or DOAC‑related bleeding in specific clinical case reports [5] [6] [7] [2]. Pharmacovigilance data on DOACs themselves identify known bleeding risk factors (age, renal function, weight) in national ADR databases, but the available SMPA analysis did not report CBD co‑use as an identified causal factor for DOAC adverse events in the presented excerpt [8].
4. Limits of the record and where uncertainty remains — what the supplied sources do not prove
The absence of CBD–DOAC case reports in these supplied sources does not prove such cases have never occurred; the case‑report literature search ends in mid‑2023 for some reviews, and spontaneous reporting systems are subject to under‑reporting, incomplete medication histories, and lag times in publication and database curation [1] [2]. The FDA and academic reviews explicitly call for more focused pharmacovigilance and clinical research to quantify interaction risks and to capture co‑use with specific drug classes such as DOACs, which means a residual evidence gap persists despite strong mechanistic rationale [9] [10].
5. Practical inference for clinicians and investigators from the available record
Given the mechanistic potential for CBD to alter CYP3A4/2C19 and P‑gp pathways and the well‑documented bleeding risks intrinsic to DOAC therapy, clinicians and safety researchers should treat co‑use as a plausible risk factor warranting medication reconciliation, patient counseling, and, when indicated, laboratory or clinical monitoring—even though the assembled literature here does not contain a published clinical case report since 2023 that incontrovertibly links CBD to an adverse DOAC outcome [3] [4] [2].