Concomitant use of Ginkgo biloba extracts is not recommended. Compounds or herbal preparations (for example Ginkgo biloba extracts) which induce CYP3A4 or CYP2B6 may give rise to decreased plasma concentrations of efavirenz.
Sustiva Summary of Product Characteristics, Bristol-Myers Squibb Pharmaceuticals Ltd, May 2023.

A case report describes a possible interaction with efavirenz and Gingko biloba. The patient had been on an antiretroviral regimen of tenofovir/emtricitabine and efavirenz for two years and had achieved an undetectable viral load. However, virological failure developed and upon questioning it was found that the patient had been taking Gingko biloba for several months. Efavirenz concentrations were determined in stored plasma samples and showed decreasing concentrations which coincided with increasing viral load. The patient was successfully switched to alternative antiretrovirals. Although the exact mechanism of the interaction remains unresolved, the authors propose that Gingko biloba extract (principally the terpenoids) may lower efavirenz plasma levels by the induction of CYP3A4 and P-gp.