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Overview: Zafirlukast is used for the long-term treatment of asthma. Common side effects include headache and nausea. Tell your healthcare provider right away if you get severe nausea or a yellowish color to your skin or the whites of your eyes. Zafirlukast is used on a regular basis. It will not stop a sudden asthma attack. Always have your rescue inhaler with you.

Uses

What is zafirlukast used for?

Zafirlukast is commonly used for the long-term treatment of asthma.

Zafirlukast may also be used for other conditions as determined by your health care provider.

How does zafirlukast work (mechanism of action)?

Zafirlukast helps improve asthma symptoms by blocking substances in the body called leukotrienes that cause inflammation and swelling in the airways.

How is zafirlukast supplied (dosage forms)?

Brands and other names

  • Accolate

Dosage forms and strengths

  • 10 mg, 20 mg oral tablets

How should I store zafirlukast?

Zafirlukast should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place in the original container. Protect zafirlukast from light.

Side Effects

What are the most common side effects of zafirlukast?

The most common side effects of zafirlukast are listed below. These side effects can vary based on the age of the person taking the medicine. Tell your health care provider if you have any of these side effects that bother you.

  • Headache
  • Infection
  • Nausea
  • Diarrhea
  • Pain, such as belly pain

There may be other side effects of zafirlukast that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of zafirlukast?

While less common, the most serious side effects of zafirlukast are described below, along with what to do if they happen.

Severe Allergic Reactions. Zafirlukast may cause allergic reactions, which can be serious. Stop taking zafirlukast and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Sleep or Mood Problems. Zafirlukast may cause new or worsened mental health problems that affect your mood, thoughts, feelings, behavior, and general well-being. These effects can occur in people with or without a history of mental health problems and may continue even after stopping zafirlukast. Tell your health care provider if you have any of the following.

  • Unusual changes in your mood, behavior, or thinking
  • Feeling sad or depressed
  • Sleep problems

High Eosinophil Levels. Eosinophils are a type of white blood cell that helps to fight disease. In some people, zafirlukast can cause eosinophil levels to rise. Small increases in eosinophil levels do not usually cause any symptoms. However, large increases in eosinophil levels can cause serious adverse effects, including swelling (inflammation) of the lungs or blood vessels. Call your health care provider right away if you have any of the following symptoms of these conditions.

  • Chest pain
  • Fever or flu-like symptoms
  • Numbness or feeling pins and needles in the arms or legs
  • Skin rash
  • Shortness of breath or cough (worse than normal)
  • Sinus pressure or pain

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking zafirlukast. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Warnings & Precautions

Who should not use zafirlukast?

Allergies to Ingredients. People who are allergic to any of the following should not take zafirlukast.

  • Accolate
  • Zafirlukast
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific zafirlukast products they stock.

Liver Problems. Zafirlukast should not be used if your liver is not working as well as it should be. If there is a concern about the health of your liver, your health care provider may do tests to see if it is working well enough to take this medicine.

What should I know about zafirlukast before using it?

Do not take zafirlukast unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share zafirlukast with other people, even if they have the same condition as you. It may harm them.

Keep zafirlukast out of the reach of children.

Zafirlukast is a medicine used on a regular basis and is not to be used when a quick response to breathing problems is needed. Zafirlukast will not stop a sudden asthma attack. Always have your rescue inhaler with you for asthma attacks.

What should I tell my health care provider before using zafirlukast?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if zafirlukast is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • A history of mental health problems
  • Liver problems

Other Medicines and Supplements. Zafirlukast may interact with other medicines and supplements. Before taking zafirlukast, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how zafirlukast could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take zafirlukast while you are pregnant or trying to get pregnant.

If you become pregnant while taking zafirlukast, you can sign up for the MothersToBaby Pregnancy Studies conducted by the Organization of Teratology Information Specialists. Call 877-311-8972 or visit https://mothertobaby.org/ongoing-study/asthma. This registry collects safety information about the use of asthma medicines during pregnancy.

Breastfeeding. Do not take zafirlukast while you are breastfeeding. Zafirlukast can pass into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does zafirlukast interact with foods or drinks?

Zafirlukast should be taken on an empty stomach. Do not take zafirlukast within one hour before meals or within two hours after meals.

It is unknown if drinking alcohol will affect zafirlukast.

Does zafirlukast interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking zafirlukast.

  • Warfarin, which is a blood thinner
  • Phenytoin (Dilantin, Phenytek, and others), which is a medicine to control seizures
  • Carbamazepine (Carbatrol, Tegretol, and others), which is a medicine commonly used to treat seizures or nerve pain
  • Erythromycin (Ery-Tab and others), which is a medicine used for bacterial infections
  • Theophylline (Elixophyllin, Theo-24), which is a medicine for asthma or certain other breathing problems
  • Fluconazole (Diflucan), which is a medicine used for fungal infections
  • A calcium channel blocker, such as amlodipine (Norvasc) or nifedipine (Procardia), which is a medicine used for high blood pressure or other conditions
  • Cyclosporine (Gengraf, Neoral, Sandimmune, and others), which is a medicine that suppresses your immune system

Some other medicines may alter the blood levels of zafirlukast, and vice versa. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with zafirlukast. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much zafirlukast?

If you or someone else has used too much zafirlukast, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of zafirlukast?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.