Drugs take time to metabolize and pass through the system in a urine test, and the same drugs are incorporated as hair grows and it takes time for the drug to be present in the hair above the scalp. But an oral fluid test will often detect drugs in a donor’s system immediately after use.
While every drug and donor is different, oral fluid is widely regarded as the most reliable specimen type for detecting recent use. Oral fluid is able to detect most drugs starting soon after ingestion and extending out for 24-48 hours after use.
It could test a variety of drugs in oral fluid including amphetamine, methamphetamines (including MDMA and its metabolite), cocaine (metabolite), marijuana (THC), opiates (codeine, morphine, 6-AM (heroin), oxycodones (oxycodone, and oxymorphone), and phencyclidine (PCP).