Why is this medication prescribed?
Zafirlukast is used to prevent asthma symptoms. Zafirlukast is in a class of medications called leukotriene receptor antagonists (LTRAs). It works by blocking the action of certain natural substances that cause swelling and tightening of the airways.
How should this medicine be used?
Zafirlukast comes as a tablet to take by mouth. It is usually taken two times a day, 1 hour before or 2 hours after meals. Try to take zafirlukast at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take zafirlukast exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Do not use zafirlukast to treat a sudden attack of asthma symptoms. Your doctor will prescribe a short-acting inhaler to use during attacks. Talk to your doctor about how to treat symptoms of a sudden asthma attack.
Continue to take or use all other medications that your doctor has prescribed to treat your asthma. Do not stop taking any of your medications or change the doses of any of your medications unless your doctor tells you that you should.
Zafirlukast may help control asthma symptoms, but it does not cure asthma. Continue to take zafirlukast even if you feel well. Do not stop taking zafirlukast without talking to your doctor.
Other uses for this medicine
Zafirlukast is also sometimes used to treat allergic rhinitis (hay fever; runny nose, watery eyes, and other symptoms caused by an allergic reaction to pollen or other substances in the air). Zafirlukast is also sometimes used to prevent breathing difficulties during exercise in people who have asthma.
What special precautions should I follow?
Before taking zafirlukast,
- tell your doctor and pharmacist if you are allergic to zafirlukast or any other medications.
- tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: anticoagulants ('blood thinners') such as warfarin (Coumadin); aspirin or aspirin-containing products; calcium channel blockers such as amlodipine (Norvasc, in Caduet), diltiazem (Cardizem, Tiazac), felodipine (Plendil), isradipine (Dynacirc), nicardipine (Cardene), nifedipine (Adalat, Procardia, others), nimodipine (Nimotop), nisoldipine (Sular), or verapamil (Calan, Covera, Isoptin, Verelan); carbamazepine (Equetro, Tegretol); cisapride (Propulsid) (not available in the U.S.); cyclosporine (Neoral, Sandimmune); erythromycin (E.E.S, Erythrocin); phenytoin (Dilantin); theophylline (Theo-Dur, others); and tolbutamide. Other medications may also interact with zafirlukast, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list. Your doctor may need to change the doses of your medications or monitor you more carefully for side effects.
- tell your doctor if you have or have ever had liver disease.
- tell your doctor if you are pregnant or plan to become pregnant. If you become pregnant while taking zafirlukast, call your doctor.
- do not breastfeed while you are taking zafirlukast.
- you should know that your mental health may change in unexpected ways while you are taking zafirlukast. You should call your doctor right away if you experience any of the following symptoms: agitation, aggressive behavior, anxiety, irritability, unusual dreams, hallucinations (seeing things or hearing voices that do not exist), depression, difficulty falling asleep or staying sleep, restlessness, suicidal behavior (thinking about harming or killing yourself or planning or trying to do so), or tremor (uncontrollable shaking of a part of the body). Your doctor will decide if you should continue taking zafirlukast.
What special dietary instructions should I follow?
Unless your doctor tells you otherwise, continue your normal diet.
What should I do if I forget a dose?
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
What side effects can this medication cause?
Zafirlukast may cause side effects. Tell your doctor if this symptom is severe or does not go away.
Some side effects can be serious. If you experience any of the following symptoms or those listed in the SPECIAL PRECAUTIONS section, call your doctor immediately.
- loss of appetite
- pain in the right upper part of your stomach
- excessive tiredness
- lack of energy
- yellowing of the skin or eyes
- flu-like symptoms
- swelling of the eyes, face, lips, tongue, or throat
- difficulty breathing or swallowing
- pain, burning, numbness, or tingling in the hands or feet
Zafirlukast may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.
What should I know about storage and disposal of this medication?
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light, excess heat, and moisture (not in the bathroom) . Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
In case of emergency/overdose
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
Symptoms of overdose may include:
What other information should I know?
Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your response to zafirlukast.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.