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Drug Interactions between montelukast and zafirlukast

This report displays the potential drug interactions for the following 2 drugs:

  • montelukast
  • zafirlukast

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Interactions between your drugs


zafirlukast montelukast

Applies to: zafirlukast and montelukast

Zafirlukast may increase the blood levels and effects of montelukast. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Contact your doctor if your condition changes or you experience increased side effects such as headache, fever, sore throat, cough, abdominal pain, diarrhea, earache, runny nose, or uncommon but serious behavior and mood changes (e.G., agitation including aggressive behavior or hostility; bad or vivid dreams; depression; confusion; difficulty concentrating; anxiety; hallucinations; irritability; memory impairment; restlessness; sleep walking; suicidal thoughts and actions; tremor; trouble sleeping). It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Drug and food interactions


zafirlukast food

Applies to: zafirlukast

Zafirlukast should be taken on an empty stomach 1 hour before or 2 hours after a meal unless otherwise directed by your doctor. You may experience reduced absorption of zafirlukast in the presence of food. This will make it easier for your body to absorb the medication.

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.


Leukotriene modifiers

Therapeutic duplication

The recommended maximum number of medicines in the 'leukotriene modifiers' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'leukotriene modifiers' category:

  • montelukast
  • zafirlukast

Note: The benefits of taking this combination of medicines may outweigh any risks associated with therapeutic duplication. This information does not take the place of talking to your doctor. Always check with your healthcare provider to determine if any adjustments to your medications are needed.

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.