Blood Drug Test

What a blood test detects and how long substances stay detectable.

Quick answer

Blood testing measures ACTIVE circulation — closest proxy to impairment, shortest windows (hours-to-a-couple-days). Hospitals order it clinically; courts order it post-accident (DUI contexts); employers rarely bother giv

Detection windows in blood

SubstanceTypical window
2C-Bhours
2C-Ihours
4-AcO-DMThours
Adderall / amphetamines~12–24 hours
Alcoholroughly 6–12 hours, tracking BAC decline (~0.015%/hr average)
Ambien (zolpidem)~12 hours
Anabolic steroidscompound-dependent
Ashwagandhan/a
Baclofenn/a
Barbiturates1–4 days (phenobarbital longer)
Benadryl / NyQuil (diphenhydramine & doxylamine)n/a
Benzodiazepines (Xanax, Valium, Klonopin, Ativan)1–2 days
Buspirone (BusPar)n/a
CBD (cannabidiol)not tested
Clonidinen/a
Coca (leaf and tea)12–48 hours
Cocaine12–48 hours
Codeine / promethazine ('lean')~12–24 hours
Creatinen/a
DMT~hours
DXM (dextromethorphan)hours
Delta-10 THC12–24 hours
Delta-8 THC12–24 hours
Dilaudid (hydromorphone)~24 h
Escitalopram (Lexapro)n/a
Etizolamhours
Fentanyl~12–48 hours
Fluoxetine (Prozac)n/a
GHB4–8 hours
Gabapentin (Neurontin)~1 day
Hempn/a for seed or fibre
Hydrocodone (Norco, Vicodin)~24 hours
Hydroxyzine (Atarax/Vistaril)n/a
K2 / Spice (synthetic cannabinoids)~1–2 days
Kavan/a
Ketamine~12–24 hours
Khat (cathinone)hours
Kratom (mitragynine)~2–3 days
LSD (acid)~12 hours
Lidocainen/a
MDMA (ecstasy/molly)~12–24 hours
MDPVhours
Melatoninn/a
Mescaline (peyote)hours
Methadone~2–3 days
Methamphetamine1–3 days
Methylphenidate~24 hours
Modafinil~1–2 days
Morphine~12–24 h
Muscle relaxers (Flexeril, Soma, tizanidine)n/a
NBOMe (25I-NBOMe)hours
NSAIDs (ibuprofen, naproxen, ketorolac)n/a
Naltrexone~1 day
Nicotine (smoking/vaping/Zyn)1–3 days (cotinine up to 10)
Nitazeneshours
Nitrous oxidemeasurable only for minutes during active use (specialised testing)
NyQuil & cold medicinesn/a
Ondansetronn/a
Opiates / opioids (heroin, morphine, codeine)~12–24 hours
Opiumhours to about 1 day
Oxycodone (Percocet, OxyContin)~24 hours
Ozempic / GLP-1 (semaglutide)n/a
PCP (angel dust)1–3 days
Peptides (BPC-157, ipamorelin)n/a
Phenibuthours
Phentermine (Adipex-P)~24 hours
Poppers (alkyl nitrites)n/a
Pregabalin (Lyrica)~1–2 days
Psilocybin mushrooms ('shrooms')~24 hours
Quetiapine (Seroquel)n/a
Salvia divinorumn/a
Sertraline (Zoloft)n/a
Sildenafiln/a
Suboxone (buprenorphine)~2–4 days
Sudafed (pseudoephedrine)n/a
Synthetic cathinones (bath salts)hours
Tianeptinehours
Tramadol (Ultram)~24 hours
Trazodonen/a
Weed / THC (cannabis)12–24 hours
Weed / THC (cannabis)up to 2 days
Wellbutrin (bupropion)n/a
Wild lettuce (lactucarium)n/a
Xylazinehours
alpha-PVP (flakka)hours

Typical published ranges; individual results vary with dose, frequency, metabolism and the assay.

Frequently asked questions

How does a blood drug test work?

Blood testing measures ACTIVE circulation — closest proxy to impairment, shortest windows (hours-to-a-couple-days). Hospitals order it clinically; courts order it post-accident (DUI contexts); employers rarely bother given logistics and cost.

How long do drugs stay detectable in blood?

It varies by substance — see the table above. Longest windows: 2C-B, 2C-I, 4-AcO-DMT.

Is a blood test accurate?

Screening results are presumptive; a non-negative blood screen is confirmed by GC-MS or LC-MS/MS before being reported as positive.

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