Approved for medical use in 1998, Efavirenz is generally used along with other medications to treat human immunodeficiency virus (HIV) infection. Basically, this medication works by decreasing the amount of HIV in the blood. And even though Efavirenz does not actually cure HIV, it may decrease your chance of developing AIDS and HIV-related illnesses such as serious infections or cancer. It is worth noting that Efavirenz comes as a capsule and as a tablet to take by mouth. It is usually taken once a day with plenty of water on an empty stomach (at least 1 hour before or 2 hours after a meal). You should always remember to take this medication at around the same time every day, even though taking it at bedtime may make certain side effects less bothersome. AS for the side effects of Efavirenz, they include rash, nausea, headache, feeling tired, and trouble sleeping. Other serious side effects include depression, thoughts of suicide, liver problems, and seizures. Remember that Efavirenz is not safe for use during pregnancy.