Butalbital, aspirin, caffeine, and codeine and Isoniazid interaction
Butalbital, aspirin, caffeine, and codeine and Isoniazid: 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 Butalbital, aspirin, caffeine, and codeine (BUTALBITAL, ASPIRIN, CAFFEINE and CODEINE PHOSPHATE) label · effective 2026-01-15
The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex.
Use of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with BUTALBITAL, ASPIRIN, CAFFEINE and CODEINE PHOSPHATE requires careful consideration of the effects on codeine, and the active metabolite, morphine.
Interactions with Drugs Affecting Cytochrome P450 Isoenzymes The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex.
…respiratory depression [see Warnings and Precautions ( 5.9 ) ] Acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment[see Warnings and Precautions ( 5.9 ) ] Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days [see Warnings and Precautions ( 5.10 ) / Drug Interactions ( 7 ) ].
Concurrent use of monoamine oxidase inhibitors (MAOIs) or use of MAOIs within the last 14 days ( 4 )
From the Isoniazid label · effective 2026-04-27
Theophylline A recent study has shown that concomitant administration of isoniazid and theophylline may cause elevated plasma levels of theophylline, and in some instances a slight decrease in the elimination of isoniazid.
Since the therapeutic range of theophylline is narrow, theophylline serum levels should be monitored closely, and appropriate dosage adjustments of theophylline should be made 7 .
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.