How long does a low dose of opana er stay in urine if snorted? Read alot online and found that it has about a 9-12 hour half life but said that it will be cleared from urine in 2-3 days and another souce said could be in urine flr 30 days! . Dont know how that is possible with a 10~ half life. Also does snorting instead of taking it orally change how fast it stays in your system? It is my first time using opana also.