Zafirlukast: what it treats, how to take it, side effects
Last updated September 3, 2026.
Zafirlukast is a leukotriene receptor antagonist - it blocks the natural substances that swell and tighten the airways. You may know it as Accolate. A daily preventive for asthma - not a rescue for the attack in progress.
What does it treat?
Asthma prevention - fewer symptoms over time, taken every day whether or not you feel them.
How do you take it?
Twice a day on an empty stomach - 1 hour before or 2 hours after meals, same times daily. Food blocks its absorption: the spacing is the design. Keep taking it even when breathing is fine - prevention works by staying in place. It never replaces your rescue inhaler. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: headache.
- Serious - call your doctor immediately: the liver set - nausea, loss of appetite, pain in the right upper part of the stomach, excessive tiredness - plus yellowing skin or eyes, dark urine, and itching; and the allergic set - rash, hives, swelling, trouble breathing.
Who should not take it?
Flag liver disease - the liver warning is this drug's known risk. Every other medication gets checked - interactions are real on this one. Do not breastfeed while taking it. If you become pregnant, call your doctor.
When is it an emergency?
Face or throat swelling, trouble breathing, or yellowing skin or eyes is urgent care. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What a Pymander AI doctor consult looks like
Illustrative example, not a real member's messages.
Common questions
Why the empty-stomach rule?
Absorption: food blocks zafirlukast from reaching the blood - taken with a meal, the dose mostly passes through. The spacing is the design: 1 hour before or 2 hours after eating, twice a day, same times daily. Anchoring to "before breakfast" and "well after dinner" is the habit that makes it automatic.
Is it a rescue inhaler replacement?
Never: it prevents symptoms over weeks; it does nothing for the attack in progress - the rescue inhaler stays carried everywhere. The honest measure of the preventive is exactly what the diary shows: rescue use falling. An attack still gets the rescue plan, and attacks that come often are a medication-review signal, not a tougher weekend.
What is the liver warning about?
The known risk of this drug: liver injury - the symptom set is specific: nausea, loss of appetite, pain in the right upper stomach, excessive tiredness, plus yellowing skin or eyes, dark urine, or itching. Those are call-immediately items. Liver disease in your history shapes the decision before the first dose.
Why take it every day when I feel fine?
Prevention logic: the drug keeps the airway-swelling signals blocked around the clock - the protection exists only while the level holds. Feeling fine is the drug working. Stopping means the protection drains over days and symptoms return to their old baseline - with no warning day to mark it.
Why did my doctor ask about breastfeeding?
Direct rule: do not breastfeed while taking zafirlukast. Pregnancy is the call-your-doctor version. Both belong to the prescriber conversation before the situation is live - the alternatives for asthma control in those windows exist, and the planning is the point.
What happens if I miss a dose of zafirlukast?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. The twice-daily rhythm forgives one late dose; the empty-stomach rule still applies to the makeup - an hour clear of food. Misses that cluster show up as symptoms creeping back: the diary notices first.