Montelukast (Oral)


Montelukast is an oral tablet that exists as the brand-name drug Singulair. It is also available as a generic drug which is cheaper than the brand-name version of the drug but may not be offered in every form or strength as the brand-name drug.

Montelukast sodium is the active element in the Singulair drug. It belongs to a group of medicines known as Leukotriene Receptor Antagonists (LTRAs). As a Leukotriene receptor antagonist montelukast inhibits or blocks the action of the Cysteinyl Leukotriene (CystLT1) receptor in the lungs and bronchial tubes from binding to it. This helps to reduce bronchoconstriction caused by the leukotriene resulting in less inflammation and nasal congestion.

Leukotrienes are substances the body releases when you inhale an allergen such as dust or pollen. It causes swelling in the lungs and tightening of the muscles around your airways which then leads to asthma symptoms. Due to its mode of action, it is not advisable to use montelukast in the treatment of severe asthma attacks.

Montelukast is available in the form of a tablet that can either be consumed whole or as a chewable tablet. It can also be administered as pellets that can be taken with soft food or dissolved in a solvent. The drug is used together with other drugs for the treatment of asthma.

Montelukast oral tablet is used in the management and control of asthma symptoms like chest tightness, difficulty breathing, and coughing. It is also used to treat perennial (all through the year) and seasonal (occurring at certain times of the year) allergies which are characterized by sneezing and an itchy, stuffy and runny nose. Moreover, Montelukast is also used to avoid the occurrence of EIB (exercise-induced bronchoconstriction), a condition which comes about when the respiratory tract in the lungs constricts when and after exercising. Narrowing of the airways may result in bronchospasm during exercise, coughs, and labored breathing or wheezing.

Condition it treats

  • Asthma

Type Of Medicine

  • Leukotriene Receptor Antagonist

Side Effects

Side effects are the adverse and unwanted effects that may accompany the desired effects or intended purpose of a drug. The effects may occur in isolation, some simultaneously while others don't occur at all, depending on how the patient reacts to the medication. Some side effects are more frequently occurring than others which come about rarely.

The most frequently occurring side effects associated with using Montelukast are high temperature (fever), severe headache, cough, nasal congestion, skin rash, sore throat, general fatigue, abdominal (stomach) pain, feeling sick and diarrhoea, heartburn, upset stomach, ear infection or earache, sinusitis infection, hoarseness, upper respiration infection (infection in the throat and nose) and tooth pain.

However, these side effects should diminish or disappear within a short while, probably a few weeks or days. But in case they persist or get worse, report them to your pharmacist or healthcare provider.

Montelukast may also have some severe side effects. The symptoms of these effects are as listed below:

Neuropsychiatric disorders which cause behavioural or mood changes whose symptoms are: confusion, aggressive behaviour or hostility, feeling anxious, tremor, restlessness, sleepwalking, vivid or terrible dreams, trouble sleeping, agitation, suicidal feelings or behaviours (trying to end one's life), hallucinations of non-existent things, depression, memory impairment, attention deficit.

Systemic eosinophilia seen by an increase of the white blood cells in the body. This condition could have signs such as: symptoms of a flu including aching muscles, sweating, or fever; lack of feeling in the arms and legs.

Swollen blood vessels also called vasculitis characterized by symptoms like: inflammation of the sinuses accompanied by severe pain, tingling or numbness in the limbs, and signs of a flu.

Blood and lymphatic system disorders with symptoms of easy bruising, increased internal bleeding, prolonged hemorrhage from scratches or spots of blood in the feces or urine, unusual bleeding in the nose, mouth or rectum.

The Stevens-Johnsons syndrome whose symptoms are: spots or hives, pain on the skin, bloating of the face or tongue or painful skin rash.

Muscle spasms, shacking and tremors

Anaphylactic or allergic reactions, symptoms of which are: hives or rashes, labored breathing, severe dizziness, itching and swelling of the face, tongue or throat.


Montelukast drug appears as a tablet, a chewable tablet, and granules administered orally or by mouth. Montelukast usually is taken once a day with or without food. For the treatment of asthma, montelukast should be taken in the evening, but for breathing difficulties during exercise, it should be taken approximately 2 hours before the exercise session. However, while on medication with montelukast on a regular basis or once a day, avoid taking an extra dose before exercising. When using montelukast to treat allergic rhinitis, it may be taken at any time of day. Ensure you take montelukast at about the same time every day.

The dosage prescribed, drug strength and form, and frequency of taking the drug depend on certain factors which include age of the patient, form of illness and the severity of the disease. The generic Montelukast oral tablet exists in 10mg strength while the chewable tablet is in 4mg and 5 mg strengths. This also applies to the drug brand name Singulair. The usual adult (over the age of 15 years) dosage for asthma is a tablet of 10 milligrams taken once every day. For asthma in children below 15 years old but above 6 years old, the prescribed dosage is a tablet of 5 milligrams once each day. Children aged 2-5years old should take one chewable 4-milligram tablet on a daily basis. All doses for asthma should be taken in the evening.

The dosage for breathing complications during exercise (EIB) in adults is a 10-milligram tablet. For younger children, the dose is a 5-mg chewable tablet. All doses for Exercise-induced bronchoconstriction should be taken at least two hours before exercise. The drug is not recommended for children below 5 years old. For both conditions in older adults (seniors), your doctor may adjust the dosage to a lower dose to prevent drug build up in the body which may increase the possibility of adverse side effects. If you are taking the oral granules, you can either put them directly into the mouth and swallow or mix with a spoonful of liquid and consume.

Follow the instructions on the prescription label cautiously, and request your healthcare provider to clarify any part you may not comprehend. You should take Montelukast oral tablet precisely as prescribed by your doctor. Montelukast drug is meant for consistent, continuous treatment. You are therefore advised not to stop using the drug either abruptly or completely. This is because by doing so you may increase your possibility of more recurrent asthma attacks, lead to persistent or worsened allergy symptoms and adverse exercise-related breathing complications.

If you take an overdose of the drug, it could have adverse effects on your body. Signs of the drug overdose may include a headache; increased thirst; throwing up; hyperactive behavior like pacing; restlessness, drowsiness, twitching or tremors, and pain in the stomach area. If you experience any of the listed effects of having taken an overdose of the drug, inform your doctor instantly or report to a poison control center near you. In case you skip or miss taking a dose of montelukast, take the dose the moment you remember. Avoid taking more than one dose concurrently by trying to make up for the missed dose; instead, skip a missed dose if it coincides with your next scheduled dose.

Major drug interactions

If two drugs are taken concurrently, they may alter each other's effect on the body as they interact. These interactions may bring about change in the absorption of the drugs and reduce or boost the effectiveness of the drugs causing the drug not to function effectively. Other times interaction may lead to the development of new adverse effects hence you should be wary when using different drugs at the same time. Drugs that interact with Montelukast may affect its working and excretion in the body.

Using montelukast with other prescription drugs, over-the-counter medications, herbal products or vitamins can result in certain interactions and side effects. Your healthcare provider or pharmacist should advise on how to handle or avert these drug interactions. You may need some dose adjustments or close examination to avoid adverse effects. Here is a compiled list of some of the drugs that can cause significant drug interactions with Montelukast:

  • Idelalisib
  • Albuterol
  • Aspirin
  • Claritin
  • Benadryl
  • Gabapentin
  • Metformin
  • Lisinopril
  • Melatonin
  • Nexium
  • Prednisone
  • Tramadol
  • Xanax
  • Xyzal
  • Zyrtec
  • Ivacaftor
  • Carbamazepine
  • Clarithromycin
  • Crofelemer
  • Dabrafenib
  • Deferasirox
  • Elvitegravir
  • Erythromycin base
  • Fosphenytoin
  • Gemfibrozil
  • Iloperidone
  • Itraconazole
  • Ketoconazole
  • Letermovir
  • Lumacaftor
  • Mitotane
  • Nefazodone
  • Nitisinone
  • Rifabutin
  • Rifampin
  • St John's wort
  • Amobarbital
  • Aprepitant
  • Armodafinil
  • Atazanavir
  • Budesonide
  • Butalbital
  • Clobetasone
  • Cortisone
  • Cyclosporine
  • Darifenacin
  • Darunavir
  • Dasatinib
  • Dexamethasone
  • Diltiazem
  • Dronedarone
  • Efavirenz
  • Ethotoin
  • Eucalyptus
  • Fluconazole
  • Fluvoxamine
  • Griseofulvin
  • Hexobarbital
  • Hydrocortisone
  • Indinavir
  • Lapatinib
  • Marijuana
  • Mephobarbital
  • Mibefradil
  • Modafinil
  • Nilotinib
  • Pentobarbital
  • Phenobarbital
  • Primidone
  • Rifapentine
  • Ritonavir
  • Sitaxentan
  • Rifabutin
  • Rifampin
  • Topiramate
  • Troglitazone
  • Verapamil
  • Voriconazole
  • Zafirlukast

Let your pharmacist or healthcare provider know if you are taking any of the drugs listed above or any other medication you are currently using. Your doctor may recommend discontinuing or changing one of the drugs. They may also advise you to adjust the dosing schedule of either of the drugs or even withdraw both medicines. However, do not start or stop using any medication without directions from your healthcare provider.


First and foremost, ensure you report to your doctor or pharmacist if you are allergic to montelukast or any other medications. Let your doctor and pharmacist know about any prescription medicine and OTC drugs, vitamins, dietary supplements, and herbal products you may be using or you that you plan to take. With this information, your healthcare provider will decide whether to change your prescription or keep an eye on you more closely for interactions or side effects. Do not, however, alter your dose or discontinue taking any medicines without the authorization of your doctor. Tell your doctor if you have liver disease or had it in the past.

Montelukast is generally thought to be safe for expectant women because studies have shown that it does not pose any danger or cause problems with the unborn baby. Nevertheless, inform your doctor if you are pregnant or planning to conceive so that they can give you appropriate direction. The drug should be used with caution and prescribed only when potential benefits outweigh the risks. Little is known of whether montelukast is released into the human milk of a lactating mother. Caution is recommended when using Montelukast in breastfeeding women. Tell your doctor if you are nursing an infant or planning to so that they can advise you accordingly on whether to stop or continue using the medication.

Montelukast use may increase the possibility of mental health deterioration as several neuropsychiatric incidences have been reported. You should be aware that your mental health may change quite unexpectedly while you are taking montelukast. Contact your doctor straight away if you experience changes in behaviour or mood or any of the symptoms of a mental breakdown which include: agitation, insomnia, anxiety, hallucinations (seeing things or hearing voices that do not exist), aggressive behaviour, irritability, strange dreams, restlessness, suicidal actions or thoughts, sleepwalking, depression, or difficulty falling asleep or staying asleep among others.

Be cautious if you are taking the drug and have phenylketonuria (PKU), a condition whereby you must follow a particular diet to prevent mental retardation. Take note that the chewable tablets contain aspartame that make up phenylalanine.

Avoid using this drug if you have a sudden asthma attack or to treat asthmaticus, which is a severe asthma attack that does not respond to treatment with an inhaler. In such a case it is a medical emergency which needs immediate attention. Montelukast works over time and is not meant to relieve sudden attacks of asthma. Therefore, in case of an asthma attack or breathing complication, use your quick-relief inhaler as prescribes which you should always carry with you.

Taking montelukast may increase your risk of particular problems in the immunity system of the body. These include systemic Eosinophilia (an increase of the white blood cells) with vasculitis and Churg-Strauss syndrome. This syndrome could cause adverse effects such as lack of feeling in the limbs, or signs of flu-like muscle pains, sweating, and fever. Individuals who have been diagnosed with aspirin sensitivity should avoid aspirin or nonsteroidal anti-inflammatory drugs while taking montelukast.

Be careful to take montelukast drug precisely as prescribed or directed by your doctor. If you take an excess of the Montelukast drug or an overdose, contact your doctor without delay or local poison control center for advice as it could cause detrimental effects. Before beginning treatment, it is essential to read and understand the prescription label well to avoid an overdose. Take the prescription at the same time every day and ensure that you do not take more than one dose in 24 hours. You should also avoid skipping or missing any doses so that you reap maximum benefits from the drug. Do not stop taking, increase or reduce your dose without authorization from your healthcare provider or pharmacist. Keep on using this medication on a regular basis to keep your asthma and allergies in check. Avoid sharing your medicines with other people because your dosage may not be suitable for them to use.


Store montelukast tablets at room temperature between 68 and 77 degrees Fahrenheit (20-25 degrees Celsius). Keep the medicine away from excessive heat and direct light. Store montelukast drug in a cool, dry place and avoid moist/damp areas like bathrooms. Keep the medicine in its original container, tightly closed. Montelukast and all drugs should be kept out of sight and reach of children. Dispose or get rid of any Montelukast product that is no longer in use or expired (out of date) appropriately. Ensure you consult your healthcare provider on how to safely dispose of unused drugs in case you don't know how or for more details on the same.


Montelukast is a prescription drug mainly used in the long-term treatment of asthma in both children and adults. The drug is also be used to alleviate allergic rhinitis or allergy symptoms like a runny nose in children or sneezing in adults. Montelukast is, however, not intended for the treatment of unexpected occurrences of illness. Patients with asthma are advised to always carry a rescue inhaler with them in case of a sudden attack. Montelukast can also be used before exercise sessions to prevent a condition, exercise-induced bronchoconstriction, which leads to constricting of airways preventing air from reaching the lungs.

The drug is available as a brand name Singulair and also a generic drug which is administered orally. It exists in the form of an oral tablet that can either be swallowed whole or as a chewable tablet. It can also be administered as granules which can be mixed with soft food or dissolved in a liquid.

Montelukast belongs to a group of drugs known as leukotriene receptor antagonists (LTRAs). Leukotrienes are compounds in the body that cause swelling of the tissues of the lungs as a reaction to allergens or diseases like hay fever. Montelukast works by inhibiting the functioning of leukotrienes which cause lung inflammation, hence providing relief for asthma and signs of allergic reactions. It helps to keep the airways open by preventing them from narrowing. It further helps prevent breathing difficulties after or when exercising. Montelukast is used to manage asthma and symptoms of allergic rhinitis, but it does not cure these conditions.

Montelukast presents with side effects, some minor and others serious, but which can be dealt with by a doctor. You are required to follow strictly all directions given by your doctor or pharmacist on the dosage of montelukast and read the prescription label well. Take caution of all the disease and drug interactions while using this medication. Follow proper storage and disposal procedures for the drug. Montelukast is mainly used in combination with other medication in the treatment of asthma but is not a cure for it.