Leukotrienes are substances released by white blood cells in the immune system in response to contact with an allergen. They cause inflammation, mucus, and airway constriction (narrowing) which together cause symptoms such as wheezing, chest tightness, shortness of breath, and cough.
Leukotriene modifiers (a.k.a. leukotriene receptor antagonists) like Singulair prevent this from happening.
Singulair is available in tablet, granule, and chewable forms under its brand name. The drug is also available as a generic.
Uses
The U.S. Food and Drug Administration (FDA) has approved Singular for:
Prevention and treatment of asthma in people over 1 Acute prevention of exercise-induced bronchoconstriction (EIB, tightening of airways) in people 6 and older Relief of seasonal allergic rhinitis (hay fever) in people 2 and older who are intolerant of or didn’t respond well to other therapies Relief of perennial (year-round) allergic rhinitis in people 6 and older who are intolerant of or didn’t respond well to other therapies
In terms of their benefits to asthma symptoms specifically, leukotriene modifiers help by decreasing:
Bronchoconstriction Mucus production Inflammation
In clinical studies, these drugs have been shown to:
Provide clinical benefit when added to an inhaled corticosteroid Allow for a lower dose of an inhaled corticosteroid Improve how much air you can force from your lungs (FEV1, a measure of lung function) Decrease nighttime asthma symptoms Improve quality of life
However, there is some evidence that long-acting beta-agonists may provide more clinical benefits when added to an inhaled steroid compared to montelukast and other leukotriene modifiers.
Off-Label Uses
Singulair is often prescribed off-label (for a non-FDA approved use) for:
COVID-19 Atopic dermatitis (eczema) Chronic urticaria (hives) Chronic obstructive pulmonary disorder (COPD) Nasal polyposis Allergic bronchopulmonary aspergillosis (an abnormal immune reaction to a fungus)
Before Taking
Singulair is typically not the first asthma medication given. Your healthcare provider will likely recommend and have you try other options first.
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The initial treatment for mild forms of asthma is a short-acting beta agonist (SABA), also known as a rescue inhaler. You use this drug as needed for asthma attacks. However, if you try a SABA and cannot tolerate it, your healthcare provider may prescribe Singulair or another leukotriene modifier.
If your asthma is too severe for a SABA alone, you will typically also be given an inhaled corticosteroid. You use the ICS regularly to prevent symptoms and the rescue inhaler for attacks.
If asthma still isn’t managed, the next step is an add-on medication such as a leukotriene modifier, long-acting beta agonist (LABA), or long-acting muscarinic antagonists (LAMA). These medications are generally taken along with an ICS.
Singulair and other leukotriene modifiers are not as effective as inhaled corticosteroids, but they can be useful if an ICS alone doesn’t control your asthma symptoms.
Drugs like Singulair are also potential alternatives if you can’t or don’t want to take an ICS. One potential advantage of leukotriene modifiers is that, as oral medications, they may be easier to take.
Signs you may need an add-on therapy or change in asthma medication:
You use your rescue inhaler more than twice a weekYou wake up with asthma symptoms more than twice a monthYou refill your rescue inhaler more than twice a year
Singulair may be an appropriate option, but there are others. Discuss what’s best for you with your healthcare provider.
Precautions and Contraindications
Singulair isn’t an appropriate drug for everyone, and it can be dangerous if used inappropriately.
Singulair doesn’t replace your rescue inhaler and won’t stop an acute asthma attack. It’s used regularly to prevent asthma attacks from occurring.
If you have phenylketonuria, it may be best to avoid the chewable version of Singulair as it contains phenylalanine.
When Singulair is intended to replace an inhaled corticosteroid, you should gradually reduce your ICS use and not go off of the drug abruptly. Your healthcare provider and pharmacist can guide you through the transition process.
It’s possible to have an allergic reaction to montelukast or other ingredients in Singulair. If you’ve ever had an allergic reaction to this medication, you shouldn’t try it again.
Other Leukotriene Modifiers
The other leukotriene modifiers currently on the market include:
Accolate (zafirlukast) Zyflo (zileuton)
Like Singulair, these drugs are approved to treat allergies and prevent asthma attacks.
Dosage
Dosages and timing vary depending on your age, condition, and the form of Singulair you take.
All listed dosages are according to the drug manufacturer. Check your prescription and talk to your healthcare provider to make sure you are taking the right dose for you.
How to Take and Store
According to the manufacturer:
For asthma and allergies: Take Singulair once a day in the evening. For exercise-induced bronchoconstriction: Take Singulair at least two hours before a physical activity that may trigger symptoms.
Singulair can be taken with or without food.
Oral granules for children must be given within 15 minutes of opening the package, so don’t open it until it’s time to give it to your child, which you can do in one of three ways:
Spoon it right into their mouthDissolve it in a teaspoon of cold or room-temperature formula or breastmilk ONLYMix it with a spoonful of applesauce, mashed carrots, rice, or ice cream (cold or at room temperature)
Throw away any of the mixture that’s left.
You should store Singulair:
At room temperature (between 68 and 77 degrees F)In its original packagingIn a dry placeAway from lightOut of the site and reach of children and pets
Side Effects
Side effects are possible with any medication. Be sure you’re familiar with the side effects of Singulair and be alert for them when you start taking the medication.
Common
While Singulair and other leukotriene modifiers are generally well tolerated, common side effects include:
Upper respiratory infectionFeverHeadachesSore throatCoughAbdominal painDiarrheaEar infection or inflammationInfluenzaRunny noseSinus inflammation
If these side effects are bothersome, talk to your healthcare provider about them.
Severe
If you have any severe side effects, call your healthcare provider or get medical help right away. Potentially serious side effects of Singulair include:
Allergic reactionBlistering, peeling, or shedding skinFlu-like symptoms: Rash, numbness or pins and needles in the limbs, sinus pain and swellingEar pain and fever (in children)
Stop taking the drug and get medical attention right away if you experience any of these symptoms of a drug allergy:
Difficulty breathing or swallowingSwelling of the face, throat, tongue, lips, or eyesHoarsenessItchingRash or hives
Warnings and Interactions
The FDA ordered the manufacturers of Singulair and other leukotriene modifiers to add a black-box warning to their labels to make you aware of potential mental health risks associated with this class of drugs.
You, your healthcare provider, and people close to you should be aware of these potential side effects:
AgitationAggressionAnxiousnessDepressionDisorientationDisturbances in attentionDream abnormalitiesHallucinationsInsomniaIrritabilityMemory impairmentObsessive-compulsive symptomsRestlessnessSleepwalkingStutteringSuicidal thoughts, behaviors, and attemptsTicsTremor
While individuals with and without a history of such concerns may experience any of these while on Singulair, it is especially important that those who have had such issues in the past inform their healthcare providers before starting the drug.
If you notice any of these side effects while on Singulair, talk with your prescribing healthcare provider immediately. The FDA recommends that your healthcare provider consider discontinuing your prescription should that occur.
Singulair is not believed to interact negatively with other medications. Still, talk to your healthcare provider about all medications, supplements, and vitamins that you currently take.
A Word From Verywell
You should never accept that your current asthma treatment plan is only somewhat effective. If a SABA or ICS are not providing you adequate control, talk to your healthcare provider about whether Singulair or another add-on medication may be right for you.
Whatever medication you take, be sure you’re familiar with the side effects and taking them exactly as directed. Your healthcare provider or pharmacist can address any questions or concerns you may have.
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