Drug interactions
Loratadine + Rifampin
Severity: Moderate
Loratadine and Rifampin: 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
Rifampin induces CYP3A4 and other enzymes, which can lower loratadine concentrations and reduce its antihistamine effect. This is rarely dangerous but may cause loss of allergy symptom control.
What this interaction means in plain words
Loratadine and Rifampin 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.
Why it happens
Induction of CYP3A4/CYP2D6 and P-gp by rifampin increases loratadine clearance.
What to do
Monitor for loss of efficacy; switch to an antihistamine less dependent on CYP metabolism, such as fexofenadine or cetirizine, if symptoms are uncontrolled.
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 Loratadine
- Acrivastine + Loratadine Moderate
- Amobarbital + Loratadine Moderate
- Fentanyl + Loratadine Moderate
- Isocarboxazid + Loratadine Moderate
- Levoketoconazole + Loratadine Moderate
- Loratadine + Mavacamten Moderate
Frequently asked questions
Can I take Loratadine with Rifampin?
MediHelp rates the interaction as moderate. Loratadine and Rifampin 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. Rifampin induces CYP3A4 and other enzymes, which can lower loratadine concentrations and reduce its antihistamine effect. This is rarely dangerous but may cause loss of allergy symptom control.
How serious is the interaction between Loratadine and Rifampin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for loss of efficacy; switch to an antihistamine less dependent on CYP metabolism, such as fexofenadine or cetirizine, if symptoms are uncontrolled.
What other medicines interact with Loratadine?
MediHelp also lists interactions of Loratadine with, for example, Acrivastine, Amobarbital, Fentanyl. The full list is on the Loratadine page.
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