No, codeine is an opiate and will not register as cocaine on a blood test. Best Answer: Yes, it is in a class of medicines called benzodiazepines, and it will show up in blood and urine tests. However, they have to be looking for it. In other words, they have to order the specific test to look for it. If they are looking for, say anemia or thyroid problems, then it won't show up. Treating and drug testing of Opioids. Need a drug test drug tesitng kits low cost accurate and approved. Free cups and free shipping with purchase of drug test or testing kit. The promethazine you MOST LIKELY took was the one with codeine in it, because phenergan does NOT show up on a drug test. I was just drug tested by my suboxone doctor, and had taken the pill (phenergan/promethazine) and it did NOT show up. While the most common way to test for codeine is via a urine sample, other ways to determine whether someone has used codeine include: saliva tests, hair tests, and blood tests. Most users are concerned with urine tests (due to their popularity) and hair tests (due to their longer window of detection). It stays in your hair for up to three months, saliva for up to four days, urine for up to three days and blood for a day. Codeine misuse can make it more challenging to take part in work and other daily activities; becoming sober will help. Hair follicle test: The last 2 to 3 months, but will not show drug use in the past 2 to 3 weeks Method of Action Codeine changes the way your nervous system and your brain detect pain and slows down the activity in your brain that creates the cough reaction, which is why it's used for pain relief and to relieve coughing. How Long Does Codeine Stay in Your System. Codeine is in the opiate class of drugs and is used as a pain reliever and cough suppressant. Codeine is most commonly prescribed in liquid form as a cough syrup. How To Pass A Codeine Drug Test. If your goal is to learn How To Pass A Codeine Drug Test you have come to the right place. Good solid facts, expert advice and proven strategies to pass a Codeine drug test is your best defense. 2 Answers (question resolved) - Posted in: codeine, drug test - Answer: Codeine will show up as an opiate. It is likely that it will be detected.