So I am safe gor taking yhe diet pill ali. Dont want to fail a drug test for a job.?

Safe? Drug test should be the least of your worries. Alli may cause severe diarrhea. I'd hate to sit through an interview with a potential employer with a raging volcano in your gut...
Diet Pills. Most diet pills are over the counter, and use caffeine, or other natural stimulant. These will not show up in a drug test. If you are overweight to obese, and have a prescribed medication such as phenteramine, then a drug test will not matter as you will have a legal prescription. Please don't try to use an illegal drug, such as cocaine, or you will lose that job!