Zafirlukast (Oral route)
Leukotriene Pathway Inhibitor
Uses of This Medicine:
Zafirlukast is used to help control the symptoms of asthma and improve lung function. However, this medicine should not be used to relieve an asthma attack that has already started.
This medicine is available only with your doctor's prescription.
Before Using This Medicine:
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of zafirlukast in children. However, safety and efficacy have not been established in children younger than 5 years of age.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of zafirlukast in the elderly. However, elderly patients are more likely to have lower respiratory tract infections and unwanted side effects, which may require caution and an adjustment in the dose for elderly patients receiving zafirlukast.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Other medical problems—
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Asthma attack, acute—Should not be used to control acute asthma.
- Churg-Strauss syndrome (a rare blood condition)—Use with caution. May make this condition worse.
- Liver disease (including cirrhosis)—Should not be used in patients with this condition.
Proper Use of This Medicine:
Zafirlukast is used to prevent asthma attacks. It is not used to relieve an attack that has already started. For relief of an asthma attack that has already started, you should use an inhaled medicine that works quickly. If you do not have another medicine to use for an attack or if you have any questions about this, check with your doctor.
Use this medicine only as directed by your doctor. Do not use more of it and do not use it more often than your doctor ordered. Also, do not stop taking this medicine without telling your doctor. To do so may increase the chance of side effects.
This medicine usually comes with patient information leaflet. It is very important that you read and understand this information. Be sure to ask your doctor about anything you do not understand.
Food may change the amount of zafirlukast that is absorbed. It should be taken on an empty stomach, 1 hour before or 2 hours after a meal.
To work properly, zafirlukast must be taken every day at regularly spaced times, even if your asthma seems better.
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For asthma:
- Adults and children 12 years of age and older—20 milligrams (mg) two times a day.
- Children 5 to 11 years of age—10 mg two times a day.
- Children younger than 5 years of age—Use and dose must be determined by your doctor.
- For asthma:
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions While Using This Medicine:
It is very important that your doctor check the progress of you or your child at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.
You or your child may be taking other medicines for asthma along with zafirlukast. Do not stop taking or reduce the dose of the other medicines, even if your asthma seems better, unless you are told to do so by your doctor.
Check with your doctor if your or your child's symptoms do not improve or if your asthma gets worse.
Stop using this medicine and check with your doctor right away if you or your child have pain or tenderness in the upper stomach; pale stools; dark urine; loss of appetite; nausea; unusual tiredness or weakness; or yellow eyes or skin. These could be symptoms of a serious liver problem.
This medicine may cause a rare blood condition called Churg-Strauss syndrome. This usually occurs in patients who have asthma or are taking oral steroid medicines that is being stopped or the dose is being reduced or lowered. Tell your doctor right away if you or your child have the following symptoms: a feeling of pins and needles, flu-like symptoms, numbness of the arms or legs, rash, or pain and swelling of the sinuses.
This medicine may cause some people to be agitated, disoriented, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed and have problems with sleep. If you, your child, or your caregiver notice any of these side effects, tell your doctor or your child's doctor right away.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
Side Effects of This Medicine:
- Less common
- Cough or hoarseness
- fever or chills
- lower back or side pain
- painful or difficult urination
- Abdominal or stomach pain
- clay-colored stools
- dark urine
- loss of appetite
- unpleasant breath odor
- unusual tiredness or weakness
- vomiting of blood
- yellow eyes or skin
- Incidence not known
- Attack, assault, or force
- attempts at killing oneself
- dry mouth
- fear or nervousness
- feeling sad or empty
- fever with or without chills
- general feeling of tiredness or weakness
- irregular heartbeats
- lack of appetite
- large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
- loss of interest or pleasure
- seeing, hearing, or feeling things that are not there
- shakiness in the legs, arms, hands, or feet
- shortness of breath
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- trembling or shaking of the hands or feet
- trouble with concentrating
- trouble with sleeping
- unable to sleep
- unusual bleeding or bruising
- Less common
- Acid or sour stomach
- back pain
- difficulty with moving
- joint pain
- lack or loss of strength
- muscle aching or cramping
- muscle pains or stiffness
- stomach discomfort or upset
- swollen joints
- Incidence not known
- Hives or welts
- redness of the skin
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Last Updated: 8/5/2022