Drug interactions
Isoniazid + Morphine
Severity: Minor
Isoniazid and Morphine: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Isoniazid has weak monoamine oxidase inhibiting activity, and a theoretical risk of serotonin toxicity exists with opioids. Clinically significant reactions with morphine are not well documented.
What this interaction means in plain words
Isoniazid and Morphine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Isoniazid belongs to Anti Bacterial; Morphine belongs to Musculoskeletal.
Why it happens
Weak MAO inhibition by isoniazid with possible additive serotonergic effect; not firmly established.
What to do
No routine action needed; monitor for agitation, tremor, hyperthermia or clonus if symptoms arise.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Morphine
- Alvimopan + Morphine Contraindicated
- Isocarboxazid + Morphine Contraindicated
- Morphine + Olanzapine / samidorphan Contraindicated
- Morphine + Phenelzine Contraindicated
- Morphine + Tranylcypromine Contraindicated
- Alfentanil + Morphine Major
Other interactions of Isoniazid
Frequently asked questions
Can I take Isoniazid with Morphine?
MediHelp rates the interaction as minor. Isoniazid and Morphine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Isoniazid has weak monoamine oxidase inhibiting activity, and a theoretical risk of serotonin toxicity exists with opioids. Clinically significant reactions with morphine are not well documented.
How serious is the interaction between Isoniazid and Morphine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine action needed; monitor for agitation, tremor, hyperthermia or clonus if symptoms arise.
What other medicines interact with Morphine?
MediHelp also lists interactions of Morphine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Morphine page.
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