Urine toxicology screen


  • Urine drug screen (UDS / UTOX) is typically ordered in trauma, psych, and altered mental status patients where there results can assist inpatient management.
  • Cooperative psych patients do not require Utox as part of the ED screen[1] (unless local policy dictates)
  • Routine testing of activated traumas is reasonable, but discretionary testing of nonactivated traumas should be adopted[2]
  • Unlikely to have any significant impact on the management of ED patients[3]
  • Drug testing alone never significantly better than history[4]
  • Appropriate in pediatric altered mental status workup, determining brain death, management of psychiatric disease (dual diagnosis treatment), and in trauma victim patients (substance abuse counseling).

Detection Interval

This is the estimated time a drug is detectable on urine drug screen after last use.[5]

ScreenInterval (Prolonged Use)
Amphetamines1-2 d (2-4 d)
Barbiturates2-4 d
Benzodiazepines1-30 d
Cannabinoids1-3 d (>1 mo)
Cocaine2 d (1 wk)
Opiates1-4 d (<1 wk)
Phencyclidine4-7 d (>1 mo)

Cross Reactivity

Many non-illicit drugs cross react with common drugs screened on the traditional urine drug screen [6][7]

AmphetaminesAmantadine, bupropion, chlorpromazine, desipramine. fluoxetine, L-methamphetamine, labetalol, methylphenidate, phentermine, phenylephrine, phenylpropanolamine, promethazine, pseudoephedrine, ranitidine, thioridazine, trazodone
BenzodiazepinesOxaprozin, sertraline
CannabinoidsDronabinol, nonsteroidal anti-inflammatory drugs, proton pump inhibitors
CocaineTopical anesthetics containing cocaine
OpiatesDextromethorphan, diphenhydramine, fluoroquinolones, poppy seeds, quinine, rifampin, verapamil
PhencyclidineDextromethorphan, diphenhydramine, ibuprofen, imipramine, ketamine, meperidine, thioridazine, tramadol, venlafaxine

True Positives and False Negatives

  • Most benzodiazepine screens look for oxazepam which is a metabolite of diazepam and chlordiazepoxide. Therefore, lorazepam, alprazolam, and clonazepam are commonly missed.
AmphetaminesMDA & MDMA
BenzodiazepinesOxazepam, temazepam, diazepam, alprazolam, triazolamLorazepam, clonazepam, midazolam
OpiatesMorphine, Codeine, HeroinFentanyl, tramadol, meperidine, methadone, oxycodone, buprenorphine, hydrocodone, hydromorphone
PhencyclidineNew screens are very specific

See Also


  1. Lukens, TW, et al. Clinical Policy: Critical Issues in the Diagnosis and Management of the Adult Psychiatric Patient in the Emergency Department. Annals of Emergency Medicine. 2006; 47(1):79-99.
  2. Dunham CM, Chirichella, TJ. Trauma Activation Patients: Evidence for Routine Alcohol and Illicit Drug Screening. PLoS ONE. 2012; 7(10): e47999.
  3. Tenenbein M. Do you really need that emergency drug screen? Clin Toxicol (Phila). 2009 Apr;47(4):286-91. PMID:19514875
  4. Perrone J, De Roos F, Jayaraman S, Hollander JE. Drug screening versus history in detection of substance use in ED psychiatric patients. Am J Emerg Med. 2001 Jan;19(1):49-51. PMID: 11146019.
  5. Courtesy Kishan Kapadia and UMEM derived from Goldfrank's Toxicologic Emergencies, 9th ed; Table 6-10
  6. Standridge, JB, et al. Urine Drug Screening: A Valuable Office Procedure. Am Fam Physician. 2010; 81(5):635-640.
  7. Brahm N. et al.Commonly prescribed medications and potential false-positive urine drug screens Am J Health Syst Pharm August 15, 2010 67:1344-1350;
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