Welcome to Just Answer. The answer depends on what type of a drug test is taken. The simplest NIDA-5 that tests for cannabinoids, cocaine, amphetamines, opiates, and phencyclidine will not check for butalbital. However, if the agency also adds the next tier of drugs (barbiturates, hydrocodone, methaqualone, benzodiazepines, methadone, propoxyphene, ethanol, and MDMA) it will show up since butalbital is a barbiturate. Barbiturates are typically detectable for 4.5-10 days after the last use. If you have a prescription for the Bupap, it does not count against you in a drug test. They are looking for illegal drugs, not the ones prescribed for your headaches.