Lorazepam and Probenecid Interaction
Drug interaction information between Lorazepam and Probenecid.
Lorazepam and Probenecid have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Lorazepam and Probenecid. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Probenecid blocks the liver from processing lorazepam, which makes the drug stay in your system longer and work more strongly.
What To Do
The dose of lorazepam should be cut in half if you are also taking probenecid.
FDA Label Information
Concurrent administration of lorazepam with probenecid may result in a more rapid onset or prolonged effect of lorazepam due to increased half-life and decreased total clearance. Lorazepam dosage needs to be reduced by approximately 50% when coadministered with probenecid. The effects of probenecid and valproate on lorazepam may be due to inhibition of glucuronidation.
Lorazepam Also Interacts With
- Valproate minor
- Clozapine minor
- Theophylline minor
- Aripiprazole minor
- Clarithromycin minor
Probenecid Also Interacts With
- Ketorolac major
- Levofloxacin major
- Amoxicillin moderate
- Amoxicillin/Clavulanate moderate
- Ceftazidime/Avibactam moderate
Frequently Asked Questions
Can I take Lorazepam and Probenecid together?
This is a minor interaction. The dose of lorazepam should be cut in half if you are also taking probenecid.
How serious is the interaction between Lorazepam and Probenecid?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Lorazepam and Probenecid interact?
Probenecid blocks the liver from processing lorazepam, which makes the drug stay in your system longer and work more strongly.
Understanding the Lorazepam and Probenecid Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Lorazepam belongs to the Benzodiazepine class and Probenecid belongs to the Uricosuric Agent class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Probenecid blocks the liver from processing lorazepam, which makes the drug stay in your system longer and work more strongly. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Lorazepam has 11 total documented interactions on file in this dataset, and Probenecid has 37. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: The dose of lorazepam should be cut in half if you are also taking probenecid. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Lorazepam or Probenecid based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.