Drug interactions
Loratadine + Primidone
Severity: Minor
Loratadine and Primidone: 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
Primidone is metabolized to phenobarbital, an enzyme inducer, and may lower loratadine and desloratadine concentrations. This may reduce antihistamine efficacy and sedation may be additive.
What this interaction means in plain words
Loratadine and Primidone have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Loratadine belongs to Respiratory; Primidone belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 by primidone and its metabolite phenobarbital increases loratadine metabolism.
What to do
Monitor for loss of allergy control and drowsiness; consider an alternative antihistamine if needed.
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 Loratadine
- Acrivastine + Loratadine Moderate
- Amobarbital + Loratadine Moderate
- Fentanyl + Loratadine Moderate
- Isocarboxazid + Loratadine Moderate
- Levoketoconazole + Loratadine Moderate
- Loratadine + Mavacamten Moderate
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Loratadine with Primidone?
MediHelp rates the interaction as minor. Loratadine and Primidone have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Primidone is metabolized to phenobarbital, an enzyme inducer, and may lower loratadine and desloratadine concentrations. This may reduce antihistamine efficacy and sedation may be additive.
How serious is the interaction between Loratadine and Primidone?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for loss of allergy control and drowsiness; consider an alternative antihistamine if needed.
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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