The drug clearance rate indicates how long a person will continue to show a positive urine test after the last time they use a particular drug. Opiates return a positive test for one to three days after last use, according to the U.S. Food and Drug Administration.
Drug clearance rates should be used as a guideline only. Time estimates are impacted by how long an individual has used the drug, the amount of drug used and the individual's metabolism. Opiates cause physical withdrawal symptoms when they leave the system, which can include anxiety, body aches, insomnia, chills, nausea, vomiting and diarrhea. The withdrawal symptoms are not dangerous but are very uncomfortable and can last up to 30 hours, reports Healthline.