Case Report: Kratom Linked to Liver Injury and CYP450 Drug Interaction With Nortriptyline

Why it matters

This peer-reviewed case report illustrates two simultaneous clinical risks: kratom can cause direct liver injury, and its alkaloids inhibit the CYP enzyme system, causing dangerous accumulation of co-administered medications. Clinicians treating patients on CYP-metabolized drugs — a broad category that includes antidepressants, antipsychotics, and many other medications — need to screen for kratom use.

The big picture

Kratom's hepatotoxic potential has been reported in dozens of case series, with an 80% cholestatic injury pattern in one systematic review of 69 cases. The CYP inhibition mechanism (primarily CYP3A4, CYP2D6, and CYP2C9) means kratom can effectively raise blood levels of co-administered drugs to toxic ranges without any change in dosing. Commercially processed kratom products — especially 7-OH-enriched extracts — may carry higher hepatotoxic and pharmacokinetic risk than traditional raw-leaf use, making product formulation an important clinical variable.

Key findings

• Case patient using raw kratom leaf developed mild, reversible cholestatic liver enzyme elevations with an R factor of 1.5-2.1, consistent with herb-induced liver injury (HILI).
• Simultaneously, the patient's nortriptyline (antidepressant) blood levels became elevated, consistent with kratom-mediated CYP2D6 inhibition reducing nortriptyline clearance.
• Dose reduction of nortriptyline partially corrected serum levels, but liver enzyme elevations persisted until kratom was discontinued.
• Normalization of both liver enzymes and nortriptyline levels following kratom cessation strongly supported a causal relationship.
• In vitro evidence suggests mitragynine and 7-OH may impair hepatic bile transporters and disrupt mitochondrial respiration, contributing to cholestatic or mixed-pattern liver injury.
• Concentrated or adulterated commercial kratom preparations may carry higher risk for liver injury and drug interactions than raw-leaf products.

What they say

The study authors concluded: "Even mild liver enzyme elevations in patients using kratom warrant evaluation, particularly with concurrent CYP-metabolized medications. This case reinforces the growing evidence of kratom's hepatotoxic potential and the importance of integrating pharmacokinetic considerations into patient care."

Bottom line

**Clinicians should screen patients on CYP-metabolized medications for kratom use — even raw-leaf kratom can cause both liver injury and dangerous elevations in co-administered drug levels, a combination that may go undetected without targeted inquiry.**