Health Guide

Montelukast (By mouth)

Montelukast (mon-te-LOO-kast)

Prevents asthma attacks and treats allergies.

Brand Name(s):


There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use it if you had an allergic reaction to montelukast.

How to Use This Medicine:

Packet, Tablet, Chewable Tablet

  • Your doctor will tell you how much medicine to use. Do not use more than directed.
  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
  • Oral granules: Do not open the packet until you are ready to use it. You can give the oral granules in one of three ways.
    • Put the oral granules directly on a spoon, then into the person's mouth.
    • Mix the granules with baby formula or breast milk that is cold or room temperature. Do not mix the granules with any other liquid.
    • Mix the granules with applesauce, mashed carrots, rice, or ice cream. Do not mix the granules with any other type of soft food.
    • If the medicine is mixed with formula, breast milk, or food, use it right away. Do not save any mixed medicine to use later.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in the original container at room temperature, away from heat and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have liver disease, have a condition called phenylketonuria (PKU), or are allergic to aspirin.
  • This medicine will not stop an asthma attack that has already started. Your doctor may prescribe another medicine for a sudden asthma attack.
  • If you use a corticosteroid medicine to control your asthma, keep using it as instructed by your doctor.
  • If any of your asthma medicines do not seem to be working as well as usual, call your doctor right away. Do not change your doses or stop using your medicines without asking your doctor.
  • This medicine may cause some people to be agitated, disoriented, irritable, or reckless. It may also cause depression or suicidal thoughts. Tell your doctor if you have any unusual thoughts or behaviors that trouble you.
  • This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, red skin rash
  • Chest pain, or a fast, pounding, or uneven heartbeat
  • Numbness or tingling in the hands, arms, legs, or feet
  • Pain and swelling in your sinuses
  • Restlessness, anxiety, irritability, mood or behavior changes, or thoughts of hurting yourself or others
  • Sudden and severe stomach pain, nausea, vomiting, fever, lightheadedness
  • Unusual bleeding or bruising

If you notice these less serious side effects, talk with your doctor:

  • Cough, sore throat, or flu symptoms
  • Headache

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 7/4/2018
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