Montelukast

Leukotriene receptor antagonists

ATC code: R03DC03 (Montelukast)

Mechanism of action

Selective CysLT1 receptor antagonist. Blocks leukotriene D4 activity in the airways – a mediator responsible for bronchoconstriction, mucosal edema, mucus secretion, and eosinophil recruitment. Taken orally once daily.

Indications

Allergic rhinitis

Second line

Second-line for allergic rhinitis when antihistamines are insufficient. Less effective than intranasal corticosteroids. Per ARIA, may benefit patients with coexisting asthma and rhinitis – one drug addresses both conditions.

Sources

Asthma

Adjunct

Add-on to ICS when asthma is uncontrolled at step 2. As add-on therapy, it is inferior to LABAs (formoterol, salmeterol) per meta-analyses. Preferred in patients with comorbid allergic rhinitis or aspirin-exacerbated respiratory disease, where the leukotriene component of inflammation is more prominent.

In children 6-14 years, montelukast may be considered an alternative to low-dose ICS when parents firmly refuse inhalers.

Sources

Exercise-induced bronchoconstriction

Second line

For exercise-induced bronchoconstriction the first-line is a short-acting bronchodilator (SABA) inhaled 5-20 minutes before exercise (ATS 2013, , GEMA). Montelukast is an add-on option for those with persistent symptoms and for patients whose asthma is mainly exercise-driven; its once-daily dosing protects for up to 24 hours. It acts more slowly and less strongly than a SABA, so it does not replace the inhaler right before exercise.

Sources

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Immune support and respiratory infection care

Not recommended

Montelukast is a leukotriene receptor antagonist. It is prescribed for asthma (as a first-line alternative) and allergic rhinitis ( 2024 guidelines). For shortness of breath or allergy prevention outside asthma or allergic rhinitis, montelukast is not used. In 2020 the added a boxed warning to the label about severe neuropsychiatric side effects: depression, anxiety, insomnia, nightmares, aggression, and suicidal thoughts and attempts. The FDA recommended avoiding montelukast for mild allergic rhinitis when other options are available (antihistamines, intranasal corticosteroids). If montelukast was prescribed for shortness of breath without confirmed asthma, consider seeking a second opinion, especially in children and adolescents.

Sources

Practical notes

Timing and administration

For asthma – 10 mg in the evening (adults). Evening dosing was used in pivotal trials; changing the time is not recommended. For exercise-induced bronchoconstriction – take 2 hours before exercise. If the patient already takes montelukast nightly, no extra dose is needed before exercise.

Monitoring

No routine laboratory monitoring is required. Neuropsychiatric symptoms must be monitored – mood changes, aggression, sleep disturbance, suicidal ideation. In 2020, the added a black box warning requiring that patients and parents be informed. The drug is discontinued if such symptoms appear.

Drug–drug interactions

1 pair found. Sorted from critical to minor.

Minor

Amiodarone

Class III antiarrhythmics (Vaughan Williams)

Mechanism

No clinically significant direct interaction. Montelukast is metabolised by CYP2C8 and CYP3A4; amiodarone moderately inhibits CYP3A4. Montelukast AUC may rise slightly, without clinical consequences.

Symptoms

The combination usually causes no specific symptoms. Each drug's individual side effects remain.

Management

No dose adjustment needed. In asthma with atrial fibrillation, the combination is standard.

Sources

FDA: Cordarone (amiodarone HCl) prescribing information (2018)

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Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMA

Spanish Medicines Information Centre (CIMA)

Label dated: 06/01/2026

FDA / DailyMed

FDA — DailyMed Drug Labels

Label dated: 05/30/2025

Safety

Boxed warning

FDA black box (2020): serious neuropsychiatric events including suicidal thoughts and actions, depression, agitation, aggression, and sleep disturbances, including in children. Prescribers must weigh benefits and risks. Patients and caregivers are instructed to seek immediate medical attention for behavioral or mood changes.

Contraindications

Hypersensitivity to montelukast or any component

Serious adverse effects

Neuropsychiatric events – aggression, anxiety, depression, suicidal ideation (FDA black box)
Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis) – rare, when corticosteroid dose is reduced
Angioedema (isolated cases)

Common adverse effects

Headache
Abdominal pain
Diarrhea
Upper respiratory infections (in pediatric trials)

PregnancyFDA B

FDA category B. Animal studies showed no teratogenicity. Human data are limited but available registries have not identified increased malformation risk.

Breastfeeding

Compatible. Hale L3. Transfers into milk in small amounts; RID about 0.7-3%. Observational data do not document clinical problems in breastfed infants. The 2020 AEMPS alert on neuropsychiatric reactions (behavioural change, depression, self-harm ideation) refers to the patient taking the drug, not to infants exposed through milk. Mild infant irritability or sleep disturbance is possible but rare and usually self-limited.

Calculate RID Full profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Montelukast used for?

Montelukast is evaluated for the following indications with varying evidence strength: Exercise-induced bronchoconstriction (evidence tier B), Allergic rhinitis (evidence tier B), Asthma (evidence tier B). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Montelukast?

Common side effects of Montelukast (≥ 1 in 100): Headache, Abdominal pain, Diarrhea, Upper respiratory infections (in pediatric trials). See the Safety section for uncommon and serious reactions.

Is Montelukast safe during pregnancy?

FDA category B. FDA category B. Animal studies showed no teratogenicity. Human data are limited but available registries have not identified increased malformation risk.

Is Montelukast compatible with breastfeeding?

Who should not take Montelukast?

Montelukast is contraindicated in: Hypersensitivity to montelukast or any component. Full list in the Safety section.

Does Montelukast carry an FDA boxed warning?

Practical notes

Timing and administration

Monitoring

Drug–drug interactions

1 pair found. Sorted from critical to minor.

Minor

Amiodarone

Class III antiarrhythmics (Vaughan Williams)

Mechanism

No clinically significant direct interaction. Montelukast is metabolised by CYP2C8 and CYP3A4; amiodarone moderately inhibits CYP3A4. Montelukast AUC may rise slightly, without clinical consequences.

Symptoms

The combination usually causes no specific symptoms. Each drug's individual side effects remain.

Management

No dose adjustment needed. In asthma with atrial fibrillation, the combination is standard.

Sources

FDA: Cordarone (amiodarone HCl) prescribing information (2018)

Pair details →

Safety

Boxed warning

Contraindications

Hypersensitivity to montelukast or any component

Serious adverse effects

Neuropsychiatric events – aggression, anxiety, depression, suicidal ideation (FDA black box)
Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis) – rare, when corticosteroid dose is reduced
Angioedema (isolated cases)

Common adverse effects

Headache
Abdominal pain
Diarrhea
Upper respiratory infections (in pediatric trials)

PregnancyFDA B

FDA category B. Animal studies showed no teratogenicity. Human data are limited but available registries have not identified increased malformation risk.

Breastfeeding

Calculate RID Full profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Montelukast used for?

What are the side effects of Montelukast?

Common side effects of Montelukast (≥ 1 in 100): Headache, Abdominal pain, Diarrhea, Upper respiratory infections (in pediatric trials). See the Safety section for uncommon and serious reactions.

Is Montelukast safe during pregnancy?

FDA category B. FDA category B. Animal studies showed no teratogenicity. Human data are limited but available registries have not identified increased malformation risk.

Is Montelukast compatible with breastfeeding?

Who should not take Montelukast?

Montelukast is contraindicated in: Hypersensitivity to montelukast or any component. Full list in the Safety section.

Does Montelukast carry an FDA boxed warning?