Drug interactions
Isoniazid + Primaquine
Severity: Moderate
Isoniazid and Primaquine: 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
Primaquine can cause dose-related hemolysis in patients with G6PD deficiency, and isoniazid has also been reported to cause hemolysis in this group. Using both may add to the risk of hemolytic anemia, although the contribution of isoniazid is small and poorly characterised.
What this interaction means in plain words
Isoniazid and Primaquine 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.
Isoniazid belongs to Anti Bacterial; Primaquine belongs to Anti Parasitic.
Why it happens
Additive oxidative stress on red cells in G6PD-deficient patients; the combined effect is not firmly established.
What to do
Test for G6PD deficiency before starting primaquine and monitor hemoglobin and urine colour if both drugs are used. Stop primaquine if signs of hemolysis develop.
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 Isoniazid
Other interactions of Primaquine
- Pimozide + Primaquine Contraindicated
- Amiodarone + Primaquine Major
- Amisulpride + Primaquine Major
- Anagrelide + Primaquine Major
- Arsenic trioxide + Primaquine Major
- Asenapine + Primaquine Major
Frequently asked questions
Can I take Isoniazid with Primaquine?
MediHelp rates the interaction as moderate. Isoniazid and Primaquine 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. Primaquine can cause dose-related hemolysis in patients with G6PD deficiency, and isoniazid has also been reported to cause hemolysis in this group. Using both may add to the risk of hemolytic anemia, although the contribution of isoniazid is small and poorly characterised.
How serious is the interaction between Isoniazid and Primaquine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Test for G6PD deficiency before starting primaquine and monitor hemoglobin and urine colour if both drugs are used. Stop primaquine if signs of hemolysis develop.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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