Efavirenz and Hydrocodone and chlorpheniramine interaction
Efavirenz and Hydrocodone and chlorpheniramine: 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 Hydrocodone and chlorpheniramine (Hydrocodone Polistirex and Chlorpheniramine Polistirex extended-release) label · effective 2025-06-26
Cytochrome P450 3A4 Interaction The concomitant use of Hydrocodone Polistirex and Chlorpheniramine Polistirex with all cytochrome P450 3A4 inhibitors may result in an increase in hydrocodone plasma concentrations, which could increase or prolong adverse drug effects and may cause potentially fatal respiratory depression.
In addition, discontinuation of a concomitantly used cytochrome P450 3A4 inducer may result in an increase in hydrocodone plasma concentration.
Avoid the use of Hydrocodone Polistirex and Chlorpheniramine Polistirex in patients taking a CYP3A4 inhibitor or inducer [ see Warnings and Precautions (5.7) , Drug Interactions (7.2 , 7.3) ].
Concomitant use with CYP3A4 inhibitors (or discontinuation of CYP3A4 inducers) can result in a fatal overdose of hydrocodone.
Avoid the use of Hydrocodone Polistirex and Chlorpheniramine Polistirex in patients taking CYP3A4 inhibitors or inducers.
From the Efavirenz label · effective 2024-03-31
Prophylaxis with appropriate antihistamines before initiating therapy with efavirenz in pediatric patients should be considered.
Narcotic analgesic: Methadone ↓ methadone * Monitor for signs of methadone withdrawal and increase methadone dose if required to alleviate withdrawal symptoms. * The interaction between efavirenz and the drug was evaluated in a clinical study.
Appropriate antihistamines and/or corticosteroids may improve the tolerability and hasten the resolution of rash.
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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.