A: If you are being tested by your employer and your results are positive due to a prescription, your employer can request a medical review. A physician called a Medical Review Officer (or MRO) who is trained to review drug screen results will call you to go over your results with you. You may be asked to provide proof that your prescription is valid, meaning that it belongs to you, that it is not expired, and that you are using it as prescribed. Based on this interview, the MRO has the authority to “overturn” your results from positive to negative. Keep in mind that if you work in a position that is considered to be safety-sensitive, the MRO may also recommend that you undergo a fitness for duty exam to determine if your prescription could interfere with your ability to perform your job while taking it.