Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Accolate (Zafirlukast). If you are concerned about side effects, discuss the risks and benefits of Accolate (Zafirlukast) with your doctor.

The following side effects have been reported by at least 1% of people taking Accolate (Zafirlukast). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• Diarrhea
• headache
• muscle aches
• nausea
• rash
• trouble sleeping
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• general feeling of being unwell
• increased frequency of infections (e.g., lack of energy, Fever or chills, difficulty breathing, cough)
• itching
• joint pain
• signs of bleeding (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• flu-like illness, rash, pins and needles or numbness of arms or legs, and severe Sinusitis
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Accolate (Zafirlukast).