• Basic Info
• Top Questions
• Clinical Info
• Interactions

Before using zafirlukast, tell your doctor if you are using any of the following drugs:

• aspirin;

• a blood thinner such as warfarin (Coumadin);

• tolbutamide (Orinase);

• erythromycin (E.E.S., E-Mycin, Ery-Tab, Erythrocin);

• theophylline (Elixophyllin, Respbid, Slo-Bid, TheoDur, and others);

• carbamazepine (Carbatrol, Tegretol); or

• phenytoin (Dilantin).

This list is not complete and there may be other drugs that can interact with zafirlukast. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

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 any of these serious side effects:

• worsening asthma symptoms;

• 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.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.