Fentanyl has an elimination half-life of 219 minutes, which is the time it takes for a healthy person to remove half of the drug from the blood. This is a short half-life, so fentanyl does not remain in the body for very long.
The length of time that fentanyl is detectable varies a great deal, depending on the individual and the particular test that the lab is using. There is considerable commercial demand for better and faster tests, so new testing procedures are being developed all the time.
Individual factors that affect the duration of fentanyl in the body include:
- Racial background
- General Health
- Genetic and physiological make-up
- Health of the liver and kidneys
- Amount of drug used
Depending on the type of drug test, fentanyl can be detected for as long as 90 days. Common tests include:
- Blood: How long does fentanyl stay in your blood? Fentanyl is not routinely tested by blood tests. However, the drug is detectable in the blood for up to 12 hours following the last dose.
- Urine: How long does fentanyl stay in your urine? It is detectable in the urine for two to three days after the last use.
- Hair: Does fentanyl show up in a hair follicle test? Although it is often called a hair follicle test, hair drug testing does not test the follicle. Rather, it looks for the presence of the drug in the first 1.5 inches of the hair shaft. This method can detect even a single drug use for a period of about 90 days, based on average rates of hair growth.