Montelukast

What Is Montelukast?

Montelukast is a medicine that blocks the action of leukotrienes, natural chemicals in the body that cause swelling, mucus, and tightening in the airways and nose.

Drug class: Leukotriene receptor antagonist (LTRA).

Approved Uses

Depending on the country and the label, montelukast is approved for:

• Asthma: regular (maintenance) treatment to help prevent asthma symptoms in adults and children, starting at about 12 months of age in some countries.
• Exercise-induced bronchoconstriction: prevention of airway narrowing that occurs during or after exercise, in people 6 years and older in some countries.
• Allergic rhinitis: relief of symptoms such as sneezing, runny nose, and nasal congestion, including seasonal and year-round allergies.

In the United States, the U.S. Food and Drug Administration (FDA) advises that montelukast be used for allergic rhinitis only when other treatments are not working or are not tolerated, because of the safety risks described later in this guide.

Montelukast is not a rescue medicine. It does not relieve sudden asthma symptoms.

Available Formulations and Strengths

Formulation	Common Strengths	Typical Age Group
Film-coated tablet	10 mg	Adults and teenagers (about 15 years and older)
Chewable tablet	4 mg, 5 mg	Younger children (strength depends on age)
Oral granules	4 mg per packet	Infants and toddlers (about 12 months to 5 years, depending on the country)

Strengths and age ranges differ by country and brand. Generic versions are widely available. Some chewable tablets contain phenylalanine, which matters for people with phenylketonuria (PKU). Check the label.

What Is the Recommended Dosage of Montelukast?

A licensed healthcare professional chooses the form and strength. The dose depends on:

• The condition being treated: asthma, exercise-induced symptoms, and allergic rhinitis have different instructions.
• Age: the strength and form are matched to the child’s age group, and adults and teenagers use the adult tablet.
• How well symptoms are controlled and any other medicines being used.
• Other health conditions, such as liver problems.

Body weight is not usually used to set the dose. Dose adjustments are generally not needed for mild to moderate kidney or liver problems, but tell your provider about any such conditions.

Dosage Forms

• Tablets
• Chewable tablets
• Oral granules

General Use Information

Montelukast is generally taken once a day. For asthma, it is typically taken in the evening. When used to prevent exercise-related symptoms, it is taken at a set time before exercise, and an extra dose should not be taken within 24 hours of the last one. It can be taken with or without food. The granules can be placed directly in the mouth or mixed with a small amount of soft, cold food, as the label directs.

Keep taking montelukast every day as prescribed, even if you feel well, and do not use it to replace an inhaled steroid unless a doctor directs you to.

How Montelukast Works

During an allergic or asthma reaction, the body releases leukotrienes. These chemicals cause the airways to narrow, swell, and produce extra mucus. In the nose, they cause swelling and a runny or stuffy nose.

Montelukast blocks the receptor that leukotrienes attach to, which helps reduce this swelling and tightening. This can lead to fewer asthma symptoms and fewer flare-ups over time.

Montelukast helps manage asthma and allergic rhinitis but does not cure them. It works best when used every day, and the benefit may take days to appear.

Is a Prescription Required to Buy Montelukast Online?

Yes. Montelukast is available by prescription only in most countries, including the United States.

Which Specialist Can Help?

• A pulmonologist (lung specialist) or allergist/immunologist often manages asthma and allergic conditions.
• A pediatrician or primary care provider commonly prescribes it for children and adults.
• An ear, nose, and throat (ENT) specialist may be involved for allergic rhinitis.

Buying Safely

• Buy only from licensed pharmacies that ask for a valid prescription.
• Be wary of sites that sell this medicine without a prescription or at prices that seem too low. Such products may be counterfeit, expired, badly stored, or have the wrong strength.
• Make sure the package is sealed, properly labeled, and has an expiration date. If anything looks odd, ask a pharmacist.

Side Effects of Montelukast

Many people tolerate montelukast well, but side effects can occur. Not everyone will have them.

Common Side Effects

• Headache
• Upper respiratory infections, such as colds, and cough
• Stomach pain or upset
• Diarrhea
• Fever
• Ear infection or ear pain (in children)
• Dizziness
• Rash
• Tiredness

Serious Side Effects

Serious side effects are uncommon but important.

• Mental health and behavior changes (neuropsychiatric events). These can include agitation, aggression, anxiety, depression, trouble sleeping, vivid dreams or nightmares, sleepwalking, irritability, hallucinations, and in rare cases thoughts of suicide or suicidal behavior. These effects have been reported in both children and adults, and they can happen soon after starting or later in treatment.
• Allergic reactions: rash, hives, swelling of the face, lips, or tongue, or trouble breathing.
• Blood vessel inflammation and related symptoms (such as a flu-like illness, numbness or tingling, severe sinus problems, or a worsening rash), which has been reported in a small number of people with asthma, often when steroid doses were lowered.
• Liver problems, shown by yellowing of the skin or eyes, dark urine, or severe stomach pain.
• Severe skin reactions, such as blistering or peeling skin.
• Bleeding or bruising more easily.

Safety Warning From Regulators

In 2020, the FDA added its strongest warning (a boxed warning) to montelukast about the risk of serious mental health side effects. Patients and caregivers should know the warning signs and watch for them.

When to Get Medical Help Right Away

Seek emergency care if there is:

• Any thought of suicide or self-harm, or talk of wanting to die
• Severe agitation, aggression, or hallucinations
• Swelling of the face, lips, tongue, or throat, or severe trouble breathing
• Yellowing of the skin or eyes with dark urine

Stop giving or taking montelukast and contact a healthcare professional right away if you notice new or worsening mood, behavior, or sleep changes, especially in a child. In a crisis, contact local emergency services or a crisis line.

Drug Interactions

Montelukast has few major interactions, but some medicines can change its levels. Give your specialist and pharmacist a full list of everything you use.

Prescription Medicine Categories

• Medicines that lower montelukast levels, such as phenobarbital and rifampin. A healthcare professional may need to review the combination.
• Medicines that raise montelukast levels, such as gemfibrozil (a cholesterol medicine).
• Other asthma and allergy medicines, including inhaled steroids, oral steroids, and other leukotriene medicines. Montelukast is often used alongside other treatments, but the combination should be directed by your doctor.
• Medicines that affect mood or sleep, which may add to mental health or sleep effects.

Over-the-Counter (OTC) Medicines

• Allergy medicines, such as antihistamines, are often used with montelukast, but check with a pharmacist before combining products.
• Cold and sleep aids may add to drowsiness or other effects.

Supplements and Herbal Products

• St. John’s wort and other herbal products can change how the body handles medicines. Ask before using them.
• Tell your healthcare professional about any supplement you use, including those for sleep or mood.

Do not start, stop, or change any medicine or supplement without telling your healthcare professional.

Safety & Important Considerations

Mental Health and Behavior Monitoring

Before starting montelukast, talk with your healthcare professional about the possible mental health effects and the benefits and risks for you or your child. People with a history of depression, anxiety, or other mental health conditions should discuss this with their provider before starting. Caregivers should watch children closely for changes in mood, behavior, or sleep.

Not for Sudden Symptoms

Montelukast does not treat a sudden asthma attack. Keep a fast-acting rescue inhaler on hand as directed, and get emergency help if breathing gets worse.

Do Not Replace Steroids on Your Own

Do not stop or lower an inhaled or oral steroid because you started montelukast unless your doctor tells you to.

Aspirin-Sensitive Asthma

People with asthma triggered by aspirin should continue to avoid aspirin and related pain medicines while on montelukast.

Liver Disease

Montelukast is processed by the liver. Tell your provider about any liver condition. Dose changes are usually not needed for mild to moderate liver problems, but it has not been well studied in severe liver disease.

Kidney Disease

No dose changes are typically needed for kidney disease, but share any kidney conditions with your provider.

Pregnancy and Breastfeeding

• Tell your healthcare professional if you are pregnant, planning pregnancy, or breastfeeding.
• Information about use in pregnancy is limited, so decisions should be made with a specialist.
• Montelukast may pass into breast milk.
• Uncontrolled asthma also poses risks in pregnancy.

Children and Older Adults

• Children: Approved ages and forms vary by country. Watch for mood, behavior, and sleep changes.
• Older adults: Dose adjustment is usually not needed, but other health conditions and medicines should be reviewed.

Conditions to Discuss Before Starting

Tell your healthcare professional if you have, or have had:

• Depression, anxiety, or other mental health conditions, or thoughts of self-harm
• Sleep problems or nightmares
• Liver disease
• Phenylketonuria (PKU), if using chewable tablets
• Allergy to any ingredient in the product
• Asthma triggered by aspirin

Monitoring

Your care team may:

• Track asthma or allergy symptoms and how often you need rescue medicine
• Ask about mood, behavior, and sleep at follow-up visits
• Check liver function in some patients

Who This Medication Is For

Montelukast is intended for:

• People with asthma who need regular, long-term treatment, as decided by their healthcare professional and within the label’s age limits.
• People who get breathing problems with exercise and need prevention.
• People with allergic rhinitis, in some cases after other treatments have not worked or have not been tolerated.

A specialist or primary care provider decides if it is appropriate after reviewing symptoms, past treatments, personal and family history of mental health conditions, and overall health.

Who Should Not Take Montelukast

Do not use this medicine if:

• You are allergic to montelukast or any other ingredient in the product.
• You need quick relief of a sudden asthma attack. Montelukast is not for this purpose.

Important Precautions

Use extra caution and speak with your specialist if you or your child has a history of depression, anxiety, mood changes, sleep problems, or thoughts of self-harm. Use extra caution with liver disease or PKU (for chewable tablets).

What to Do If You Miss a Dose

• If you miss a dose, skip it and take the next dose at the usual time.
• Never double up or take extra doses to catch up.
• For exercise prevention, do not take a second dose within 24 hours of the last one.
• If you often forget doses or are unsure what to do, contact a licensed healthcare professional or pharmacist.
• If symptoms worsen after a missed dose, follow your asthma action plan and get medical help if needed.

Related medications to Montelukast

Other medicines used for similar conditions include:

• Inhaled corticosteroids, often the main long-term asthma treatment
• Inhaled corticosteroid and long-acting bronchodilator combinations (ICS/LABA)
• Other leukotriene-pathway medicines, such as zafirlukast or zileuton
• Oral or nasal antihistamines for allergic rhinitis
• Nasal corticosteroid sprays for allergic rhinitis
• Biologic medicines for certain types of severe asthma

These options differ in how they are taken, how they work, and their side effects. Do not switch or stop treatment without guidance. Any change should be made after consulting a licensed medical specialist.

Storage Instructions

• Store at room temperature, usually about 68°F to 77°F (20°C to 25°C), unless the label says otherwise.
• Keep tablets and granules dry, in the original package, and away from moisture, such as steamy bathrooms.
• Protect from light and heat.
• For granules, give the dose within the time stated on the label after opening the packet (commonly within 15 minutes if mixed with food).
• Keep out of reach and sight of children and pets. Chewable tablets may look like candy, so store them safely.
• Dispose of expired or unused medicine as advised by your pharmacist or local disposal program.

Disclaimer:

This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Patients must consult a licensed pulmonologist, allergist, or other relevant medical specialist before starting, changing, or stopping treatment. Treatment decisions must be based on a full clinical evaluation by a qualified specialist. Always follow the prescribing information and Medication Guide provided with your medicine.