Routine urine barbiturate screens detect barbiturate-class drugs such as phenobarbital, pentobarbital, secobarbital, amobarbital, butalbital, mephobarbital and methohexital. Primidone may also yield a positive result because it metabolizes to phenobarbital. Detection windows and test sensitivity vary by drug, dose and assay; confirmatory testing (e.g., GC‑MS) distinguishes specific compounds.

Barbiturates are typically detectable in urine for about 1–7 days for short‑ and intermediate‑acting agents and up to roughly 2–3 weeks for long‑acting barbiturates (for example, phenobarbital). Detection windows vary with dose, frequency, metabolism, liver/kidney function, urine pH, and the assay used (immunoassay vs GC‑MS); chronic or heavy use usually prolongs detection.

Barbiturates are central nervous system depressants that include drugs such as phenobarbital, pentobarbital (Nembutal), secobarbital (Seconal), thiopental (Pentothal), amobarbital, methohexital, and butalbital. They were used for seizures, anesthesia and insomnia but have largely been replaced by safer benzodiazepines and other agents because of overdose and dependence risks. Some remain in limited clinical use under strict control.

Urine drug screens commonly test for amphetamines/methamphetamines, cocaine (benzoylecgonine), THC metabolites, opioids (morphine/codeine/heroin metabolites), and PCP — the standard 5‑panel. Expanded panels add benzodiazepines, barbiturates, methadone, buprenorphine, and oxycodone/oxymorphone. Results depend on the specific panel and lab; specialized assays detect synthetic opioids and designer drugs. Detection windows vary by drug, dose, and individual factors.

Identify barbiturate use/overdose by history and characteristic CNS depression — drowsiness, slurred speech, ataxia, progressing to respiratory depression, hypotension, reduced reflexes and possibly coma; pupils are often normal. Confirm with toxicology: urine or serum immunoassay screening with GC‑MS confirmation and blood levels for severity. Pill ID by imprint/manufacturer; detection windows vary by drug.

Cetirizine, a non‑sedating antihistamine, does not show up on standard workplace or legal drug screens and is unlikely to cause a positive result for drugs of abuse. Very rarely immunoassay cross‑reactivity can produce false positives, but confirmatory tests (GC‑MS) will distinguish substances. If concerned, disclose your prescription and bring medication packaging to the testing site.