Drug interactions
Codeine + Terbinafine
Severity: Moderate
Codeine and Terbinafine: moderate 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
Terbinafine is a strong CYP2D6 inhibitor and can reduce conversion of codeine to morphine, weakening analgesia. The effect resembles poor metabolizer status. Toxicity risk is generally not increased, though diminished pain relief can lead to dose escalation.
What this interaction means in plain words
Codeine and Terbinafine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Codeine belongs to Musculoskeletal; Terbinafine belongs to Anti Fungals.
Why it happens
CYP2D6 inhibition by terbinafine reduces O-demethylation of codeine to morphine.
What to do
Assess analgesic response during terbinafine therapy and consider a non-CYP2D6-dependent analgesic if pain control is inadequate. Avoid simply raising the codeine dose.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Codeine
- Alvimopan + Codeine Contraindicated
- Codeine + Isocarboxazid Contraindicated
- Codeine + Olanzapine / samidorphan Contraindicated
- Codeine + Phenelzine Contraindicated
- Codeine + Tranylcypromine Contraindicated
- Alfentanil + Codeine Major
Other interactions of Terbinafine
- Terbinafine + Thioridazine Contraindicated
- Desipramine + Terbinafine Major
- Eliglustat + Terbinafine Major
- Flecainide + Terbinafine Major
- Imipramine + Terbinafine Major
- Maprotiline + Terbinafine Major
Frequently asked questions
Can I take Codeine with Terbinafine?
MediHelp rates the interaction as moderate. Codeine and Terbinafine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Terbinafine is a strong CYP2D6 inhibitor and can reduce conversion of codeine to morphine, weakening analgesia. The effect resembles poor metabolizer status. Toxicity risk is generally not increased, though diminished pain relief can lead to dose escalation.
How serious is the interaction between Codeine and Terbinafine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Assess analgesic response during terbinafine therapy and consider a non-CYP2D6-dependent analgesic if pain control is inadequate. Avoid simply raising the codeine dose.
What other medicines interact with Codeine?
MediHelp also lists interactions of Codeine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Codeine page.
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