Hydrocodone, a commonly prescribed opioid for pain relief, can remain in the body for different lengths of time depending on dosage, metabolism, and frequency of use. On average, hydrocodone stays in urine for up to 2–4 days, in blood for about 24 hours, in saliva for 12–36 hours, and in hair for up to 90 days. Understanding how long hydrocodone stays in your system is important for safe use, medical testing, and avoiding potential interactions.