Montelukast

is prescribed to treat:

• Asthma and seasonal allergies • Various related conditions in the respiratory category • Associated symptoms and complications

It is an important medication that helps manage these conditions effectively.

Montelukast (Singulair) is a leukotriene receptor antagonist used for asthma maintenance, exercise-induced bronchoconstriction, and allergic rhinitis. It is taken as a once-daily tablet rather than inhaled, which accounts for much of its popularity — and its neuropsychiatric boxed warning has substantially changed how it should be positioned.

Mechanism of Action

Montelukast selectively blocks the cysteinyl leukotriene receptor CysLT1. Cysteinyl leukotrienes are inflammatory mediators produced by mast cells and eosinophils through the 5-lipoxygenase pathway, and they are potent bronchoconstrictors — considerably more so than histamine — as well as drivers of mucus secretion, eosinophil recruitment, and airway edema.

Blocking that receptor reduces bronchoconstriction and airway inflammation. Because leukotrienes are only one of several inflammatory pathways in asthma, montelukast is a partial rather than comprehensive anti-inflammatory: inhaled corticosteroids such as fluticasone or budesonide suppress a broader range of mechanisms and are consistently more effective as controller therapy.

The leukotriene pathway is disproportionately important in two specific groups: patients with exercise-induced bronchoconstriction, and those with aspirin-exacerbated respiratory disease, where NSAID exposure shunts arachidonic acid metabolism toward leukotriene production. In both, montelukast performs better than its average would suggest.

Montelukast is not a rescue medication. It has no bronchodilator effect in an acute attack, and patients must understand that albuterol remains the drug for acute symptoms.

Clinical Use

In asthma, guidelines place inhaled corticosteroids first for persistent disease. Montelukast is an alternative when inhaled steroids cannot be used or tolerated, and an add-on when they are insufficient — though a long-acting beta agonist added to an inhaled steroid generally outperforms montelukast as the first add-on.

Where montelukast earns a stronger position is exercise-induced bronchoconstriction, aspirin-exacerbated respiratory disease, and patients with concurrent allergic rhinitis, where a single oral tablet treats both the upper and lower airway. Inhaler technique is a persistent real-world problem, and an oral tablet sidesteps it entirely — a legitimate advantage for patients who cannot use a device reliably.

In allergic rhinitis, montelukast is less effective than intranasal corticosteroids and roughly comparable to oral antihistamines such as cetirizine or loratadine. Given the safety profile, it is not a first choice for rhinitis alone. The Florida allergies article covers the local picture, where year-round exposure changes the calculation, and the asthma and COPD in humid St. Pete article addresses climate-specific triggers. Our pulmonary team manages the more difficult asthma cases.

Monitoring and Follow-Up

The neuropsychiatric warning dominates monitoring. In 2020 the FDA added a boxed warning after continued reports of agitation, aggression, depression, sleep disturbance, vivid dreams, anxiety, hallucinations, and suicidal thoughts and behaviour — including in patients with no psychiatric history and including children. The agency explicitly advised reserving montelukast for allergic rhinitis only when other treatments are inadequate.

This changes practice concretely. Patients and, for children, parents should be told about these effects before the first dose rather than discovering them later, and asked about mood, behaviour, and sleep at follow-up. The symptoms typically resolve after stopping, but they are frequently attributed to something else — school stress, adolescence, an unrelated life event — precisely because nobody connects them to an allergy tablet. The FDA safety communication sets out the reasoning.

Otherwise there is no laboratory monitoring. Asthma control should be assessed objectively — symptom frequency, rescue inhaler use, night waking, activity limitation — rather than by impression, and a patient using a rescue inhaler more than twice a week is inadequately controlled regardless of what they report. The MedlinePlus montelukast entry covers the prescribing detail.

Expectation-setting matters here as much as anywhere. Montelukast produces a modest improvement for most patients rather than a dramatic one, and its effect is often not perceptible day to day in the way a bronchodilator is. Patients who expect to feel it working sometimes conclude it does nothing and stop, while those told to judge it over weeks by rescue inhaler use and night symptoms assess it far more accurately. It is also worth naming that a meaningful minority simply do not respond, since leukotrienes are only one inflammatory pathway among several — a non-responder is a reason to change approach, not to escalate the dose.

Special Populations

In children, montelukast is widely used because oral dosing is simpler than inhaler technique in young patients, but the neuropsychiatric risk applies to them too and parents deserve an explicit conversation. Behavioural change in a child on montelukast should prompt review of the drug rather than a behavioural referral.

In pregnancy, available data are reassuring and montelukast is continued when it is providing genuine benefit, since uncontrolled asthma poses a clear risk to both mother and fetus. No dose adjustment is needed in kidney impairment; significant hepatic impairment warrants caution. Montelukast should not be stopped abruptly in a patient whose asthma it is controlling without a replacement controller in place.

Timing is conventionally in the evening, which reflects the nocturnal pattern of asthma symptoms and the circadian rhythm of airway inflammation rather than anything about absorption. For exercise-induced bronchoconstriction specifically, a dose taken at least two hours before activity provides protection lasting up to 24 hours, which suits patients who exercise unpredictably better than a pre-exercise inhaler does. Tolerance does not develop to that protective effect, unlike with regular short-acting beta agonist use. If the evening dose is consistently forgotten, moving it to a time the patient will reliably remember is better than persisting with a theoretically optimal schedule nobody follows.

When to Contact Your Doctor

Report any change in mood or behaviour — new agitation, aggression, depression, anxiety, unusual dreams, sleepwalking, difficulty sleeping, or any thought of self-harm — promptly, and stop the drug pending review. In children this includes irritability, unusual outbursts, or a change in school performance. Increasing rescue inhaler use, night waking with symptoms, or reduced exercise tolerance indicate deteriorating control and need reassessment rather than a higher dose. Any severe breathing difficulty is an emergency, and montelukast has no role in treating it.

To review your asthma or allergy control, or whether montelukast is still the right choice for you, contact us or schedule a visit.