依法韦仑（英文：Efavirenz）是一种抵抗艾滋病毒的特效药物。依法韦仑的商业名称为Sustiva® 或Stocrin®，它是一种属于非核苷逆转录酶抑制物（NNRTI -- non-nucleoside reverse transcriptase inhibitor）类别的药物，可在高活性抗逆转病毒疗法中使用，进行医治甲类人体免疫性病毒（HIV type 1）。

依法韦仑可用于医治未被医治过的HIV病毒感染者，她的优点是能与lamivudine、zidovudine或tenofovir等药物共用作为比较优异的NNRTI-培养基（regimen）。

Efavirenz (EFV), sold under the brand names Sustiva among others, is a non-nucleoside reverse transcriptase inhibitor (NNRTI). It is used as part of highly active antiretroviral therapy (HAART) for the treatment of a human immunodeficiency virus (HIV) type 1. For HIV infection that has not previously been treated, the United States Department of Health and Human Services Panel on Antiretroviral Guidelines currently recommends the use of efavirenz in combination with tenofovir/emtricitabine (Truvada) as one of the preferred NNRTI-based regimens in adults and adolescents. Efavirenz is also used in combination with other antiretroviral agents as part of an expanded postexposure prophylaxis regimen to reduce the risk of HIV infection in people exposed to a significant risk (e.g. needlestick injuries, certain types of unprotected sex etc.).