Answer
Efavirenz can produce false-positive results with some urine screening assays. A more specific confirmatory test can distinguish this from cannabinoid exposure.
Sources for this answer
- Efavirenz/emtricitabine/tenofovir disoproxil Milpharm 600 mg/200 mg/245 mg film-coated tablets — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.