Montelukast Viatris (Montelukast)

Montelukast acts on the leukotriene pathway to control airway inflammation and allergic symptoms.

• Asthma: improves long‑term control and reduces the frequency of exacerbations.
• Allergic rhinitis: relieves nasal congestion, sneezing and itchy eyes.
• Exercise‑induced bronchoconstriction: prevents airway narrowing triggered by physical activity.

• Montelukast selectively blocks the cysteinyl leukotriene receptor CysLT1, preventing leukotrienes D4, E4 and F4 from binding. This inhibition reduces bronchoconstriction, vascular permeability, and inflammatory cell recruitment in the respiratory tract, thereby improving airway patency and alleviating allergic inflammation.

Montelukast is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Headache: mild to moderate discomfort.
• Abdominal pain: intermittent stomach discomfort.
• Cough: occasional dry cough.
• Sore throat: mild irritation of the throat.
• Nasopharyngitis: common cold‑like symptoms.
• Diarrhoea: loose stools.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips or tongue.
• Allergic reactions: rash, itching or hives.
• Mood changes: agitation, depression or anxiety.
• Suicidal thoughts: rare but reported ideation.
• Hepatic dysfunction: elevated liver enzymes.
• Severe bronchospasm: paradoxical worsening of breathing.

Use Montelukast with clinical oversight and consider patient‑specific factors.

• Hypersensitivity: avoid if known allergy to montelukast or excipients.
• Psychiatric disorders: monitor for mood changes or suicidal ideation.
• Pregnancy: use only if potential benefit justifies potential risk, as data are limited.
• Pediatric use: follow age‑specific labeling and dosing recommendations.
• Drug interactions: review concomitant medications for enzyme inducers or inhibitors.
• Store at ambient temperature: keep in the original container, protect from moisture and heat.

Montelukast may interact with drugs that affect its metabolism or pharmacodynamic profile.

Major Interactions (Avoid)

• Phenobarbital: induces hepatic enzymes, reducing montelukast exposure.
• Rifampin: strong enzyme inducer that lowers plasma concentrations.
• St. John's wort: herbal inducer that may diminish therapeutic effect.

Moderate Interactions (Monitor Closely)

• Warfarin: potential alteration of anticoagulant effect.
• Beta‑blockers: may blunt bronchodilatory response.
• Other leukotriene modifiers: increased risk of adverse events.
• Fluconazole: enzyme inhibitor that could raise montelukast levels.
• Cyclosporine: possible pharmacokinetic interaction requiring observation.