Lorazepam and Phenobarbital interaction
Lorazepam and Phenobarbital: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Lorazepam (LOREEV XR) label · effective 2025-10-08
Caution patients receiving LOREEV XR against operating machinery or driving a motor vehicle as well to avoid the concomitant use of alcohol and other CNS depressant drugs during treatment ( 5.4 , 7 )
Prescribe the lowest effective dosage; avoid or minimize concomitant use of CNS depressants and other substances associated with abuse, misuse, and addiction (e.g., opioid analgesics, stimulants); and advise patients on the proper disposal of unused drug.
Use of benzodiazepines, including LOREEV XR, both used alone and in combination with other CNS depressants, may lead to potentially fatal respiratory depression.
Alcohol should be avoided and other CNS depressant drugs used with caution during treatment with LOREEV XR [see Drug Interactions ( 7 )] .
CNS depressants: Additive CNS depressant effects (7)
From the Phenobarbital (SEZABY) label · effective 2025-12-23
CNS depressants: Closely monitor for sedation and respiratory depression.
CNS Depressants Closely monitor for signs of sedation and respiratory depression with concomitant use of SEZABY with other CNS depressants, including opioids [see Warnings and Precautions (5.1)] .
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.