Zafirlukast is used to treat and prevent asthma attacks in adults and children as young as 5 years old. Do not give this medication to a child without a doctor's advice.
Zafirlukast may also be used for purposes not listed in this medication guide.
How to use
Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
Zafirlukast is usually taken once daily in the evening for prevention of asthma or allergy symptoms. Follow your doctor's instructions.
Take zafirlukast on an empty stomach, at least 1 hour before or 2 hours after a meal. Zafirlukast will not work fast enough to treat an asthma attack that has already begun. Use only a fast-acting inhalation medicine to treat an asthma attack. Talk with your doctor if any of your asthma medications do not seem to work as well in treating or preventing attacks. It may take up to several weeks before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve after several weeks of treatment. Asthma is usually treated with a combination of drugs. Use all medications as directed by your doctor. Read the medication guide or patient instructions provided with each medication. Do not change your doses or medication schedule without your doctor's advice, even if you have no asthma symptoms.
Call your doctor right away if you feel that this medicine is not working as well as usual, or if it makes your condition worse. If it seems like you need to use more of any of your medications in a 24-hour period, talk with your doctor.
Drug Class and Mechanism
Zafirlukast is a leukotriene (loo-koe-TRY-een) inhibitor. Leukotrienes are chemicals your body releases when you breathe in an allergen (such as pollen). These chemicals cause swelling in your lungs and tightening of the muscles around your airways, which can result in asthma symptoms.
Missed Dose
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
Storage
Store at room temperature away from moisture and heat.
Warnings/Precautions
Do not use this medication if you are allergic to zafirlukast.
To make sure you can safely take zafirlukast, tell your doctor if you have liver disease.
The chewable tablet form of this medication may contain up to 0.842 milligrams of phenylalanine. Talk to your doctor before using this form of zafirlukast if you have phenylketonuria (PKU).
Tell your doctor if you are pregnant or plan to become pregnant during treatment. Zafirlukast can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.
Possible Side Effects
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have a serious side effect such as:
worsening asthma symptoms;
mood or behavior changes, anxiety, depression, or thoughts about suicide or hurting yourself;
skin rash, bruising, severe tingling, numbness, pain, muscle weakness; or
nausea, stomach pain, loss of appetite, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).
Less serious side effects may include:
headache;
nausea, vomiting, diarrhea, stomach pain;
weakness;
dizziness;
muscle pain; or
fever, sore throat, cold symptoms.
More Information
Your pharmacist can provide more information about zafirlukast.
