Singulair®
Montelukast Sodium
Version 2025-04 · Last reviewed April 1, 2025 · Methodology
List Price
$250+ (brand historical)
With Insurance
$15–30
How It Works
Montelukast blocks leukotriene receptors — the receptors that trigger bronchoconstriction, mucus production, and sneezing in response to allergens. Leukotrienes are released by mast cells during allergic reactions; blocking their receptor prevents these downstream effects.
Why the side effects happen
The neuropsychiatric side effects (depression, suicidal thoughts, nightmares, aggression) are the most serious and least understood. CysLT1 receptors exist in the brain — particularly in the hippocampus and cortex. Blocking them may interfere with normal brain leukotriene signaling. The FDA added a black box warning in 2020 after years of post-marketing reports, though causality was disputed. The risk appears real enough to warrant the warning.
When Will I Feel It?
Bronchoprotection begins within 24 hours. Allergy symptom relief takes 3–7 days. Full seasonal allergy effect takes 4 weeks.
Bronchoprotection against exercise-induced bronchospasm begins within 24 hours.
Allergy symptom relief (sneezing, runny nose, nasal congestion) begins improving.
Full effect for allergic rhinitis. Re-evaluate whether singulair is needed or if antihistamines alone suffice.
Adherence Note
In 2020, the FDA added a black box warning for neuropsychiatric events (depression, suicidal thoughts, sleep disturbances, behavioral changes). Monitor for mood changes in yourself or children. For mild allergic rhinitis, an antihistamine is equally effective without the psychiatric risk.
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Common Side Effects
While taking this medication, you may experience the following common side effects. We've included tips on how to manage them.
Headache
18%Common and usually mild; typically resolves. Ensure adequate hydration.
Neuropsychiatric effects (anxiety, nightmares, agitation)
10–15%FDA BLACK BOX 2020: Stop immediately if any behavioral changes, mood changes, or suicidal thoughts occur.
Aggression / behavioral changes (children)
10%Document baseline behavior before starting. Inform school staff. Stop if aggression worsens.
Abdominal pain
4%Take with food; usually self-limited.
Fatigue
3%Usually mild; evening dosing may reduce daytime impact.
Serious Adverse Effects
- • BLACK BOX WARNING (2020): Serious neuropsychiatric events including suicidal thoughts and actions — FDA added this warning after 12 years of known signal
- • Depression — stop drug immediately and seek care if depressive symptoms emerge
- • Eosinophilic granulomatosis with polyangiitis (EGPA/Churg-Strauss) — rare vasculitis; watch for rash, nerve pain, or worsening respiratory symptoms
- • Anaphylaxis — rare hypersensitivity reaction; get emergency care if severe allergic reaction occurs
Drug Interactions
Moderate Interactions (Caution)
Food Interactions
When to Contact Your Doctor
This medication requires ongoing medical supervision. The following situations warrant a prompt conversation with your prescribing physician — do not wait for your next scheduled appointment.
Contact soon if you notice
- BLACK BOX WARNING (2020): Serious neuropsychiatric events including suicidal thoughts and actions — FDA added this warning after 12 years of known signal
- Depression — stop drug immediately and seek care if depressive symptoms emerge
- Eosinophilic granulomatosis with polyangiitis (EGPA/Churg-Strauss) — rare vasculitis; watch for rash, nerve pain, or worsening respiratory symptoms
- Anaphylaxis — rare hypersensitivity reaction; get emergency care if severe allergic reaction occurs
- Suicidal thoughts or self-harm in children — discontinue immediately and seek emergency care
Also discuss if you want to
- Review whether this medication is still appropriate for you
- Consider dosage adjustments based on response
- Explore lifestyle or non-drug alternatives
- Understand stopping or tapering options
- Plan monitoring labs and follow-up
In the US, call 911 or go to the nearest emergency room for severe symptoms. Poison Control: 1-800-222-1222.
Special Populations
Safety classifications for specific groups — discuss with your provider before use.
Animal data reassuring; limited human data. Use only if clearly needed.
Likely excreted in breast milk; monitor infant for sedation or behavioral changes.
Asthma and allergic symptoms can worsen during the menopause transition due to hormonal effects on airway inflammation. Progesterone has bronchodilatory properties, and its decline during perimenopause can increase airway reactivity. If asthma or allergy symptoms are worsening in the late 30s or 40s, hormonal changes may be contributing.
FDA 2020: black box warning for serious neuropsychiatric events including suicidal thoughts and actions. FDA states drug should not be used for mild allergic rhinitis when other options exist. Discuss risks explicitly with parents.
No specific concerns; standard dosing. Monitor for neuropsychiatric effects.
FDA Adverse Event Reports
Patient-filed reports from the FDA FAERS database · refreshed daily
Community Reports
User-reported experiences — anonymous & anecdotal
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Metabolic & Lifestyle Alternatives
Addressing Allergies & Asthma at the Root — Without Neuropsychiatric Risk
Allergen immunotherapy treats root cause; HEPA filtration and anti-inflammatory diet reduce inflammatory burden without any psychiatric side effects
Important context: Evidence quality varies across these approaches. Some are well-studied with randomized controlled trial data; others are based on observational or smaller studies. These interventions are not guaranteed to replace medication for all patients. Discuss with your doctor whether any of these are appropriate for your clinical situation.
Allergen immunotherapy (sublingual or injections)
Desensitization over 3–5 years
Modifies underlying immune response; reduces both allergy and asthma symptoms long-term; only treatment that changes disease course
HEPA air purification
True HEPA filter in bedroom and main living area
Reduces indoor allergen exposure by 50–90%; directly reduces allergic triggers
Saline nasal rinse (Neti pot)
Twice daily during allergy season
Clears allergens from nasal mucosa; reduces rhinitis symptoms significantly; zero side effects
Quercetin (500mg twice daily)
Natural leukotriene inhibitor
Inhibits mast cell degranulation; reduces histamine release; anti-leukotriene properties similar to montelukast mechanism
Vitamin D optimization
Target 40–60 ng/mL
Low vitamin D strongly associated with asthma severity; supplementation reduces asthma exacerbations
Global Prescribing & Pricing
Many European countries moved Singulair to second-line or restricted use after the 2020 FDA black box warning — US prescribing continued largely unchanged
United States
$15–30 (generic)/mo
Still widely prescribed despite 2020 black box; prescribing barely changed post-warning
FDA black box added March 2020; prescribers expected to counsel on neuropsychiatric risks but no mandatory restriction
Usually covered
United Kingdom
~$5–12/mo
NICE downgraded to second-line; significant prescribing decline after 2020
MHRA issued same neuropsychiatric warning; NICE guidelines pushed toward ICS (inhaled corticosteroids) as first-line
Covered by NHS with review
Germany
~$8–18/mo
Prescribing declined significantly post-2020 warning
BfArM issued strong warning; national prescribing guidelines shifted away from montelukast for mild disease
Covered by GKV
France
~$6–14/mo
ANSM warned early; prescribing rate lower than US throughout
ANSM issued neuropsychiatric alert in 2019 before FDA; clinical reviewers re-evaluated indications
Covered by Sécurité Sociale
Japan
~$10–22/mo
Lower use; behavioral first-line for pediatric asthma management
PMDA added neuropsychiatric warning; inhaled corticosteroids and trigger avoidance emphasized first
Covered by JHIS
The FDA knew about Singulair's neuropsychiatric signal as early as 2008. The black box warning wasn't added until 2020 — 12 years later. During that gap, the drug was prescribed to tens of millions of children. France's ANSM warned its physicians a full year before the FDA acted. US prescribing rates barely changed after the 2020 black box was added.
Clinical Trials & Funding
Understanding who funds research helps contextualize results. Industry-funded trials are not automatically invalid — they undergo the same FDA review — but declared conflicts and sponsor effects are worth knowing. All linked trials can be verified on ClinicalTrials.gov.
Funding Sources
Merck funded the pivotal approval trials for Singulair. Neuropsychiatric signals were reported to the FDA as early as 2008, but Merck did not proactively add warnings for 12 years. In 2020, the FDA added the strongest possible black box warning for neuropsychiatric events including suicidal thoughts and actions — for a drug prescribed to children as young as 6 months. A Senate investigation found Merck's internal communications showed awareness of these risks earlier than disclosed.
Declared Conflicts of Interest
Merck-funded key opinion leaders actively promoted Singulair for mild asthma over cheaper alternatives. The neuropsychiatric signal was downplayed in communications to physicians for years. After the black box was added in 2020, the FDA explicitly stated the drug should no longer be used for mild symptoms "when there are other options."
Key Efficacy Results
Modest improvement in FEV1 (lung function) and allergy symptoms; neuropsychiatric events in 10–20% of pediatric patients based on post-marketing data
Referenced Studies
Each study carries a Cochrane RoB-2 risk-of-bias badge — tap the badge for details.
Evidence & Transparency
Cochrane RoB-2 (Risk of Bias)
Badges reflect an editorial assessment using Cochrane's RoB-2 tool domains: randomization, intervention deviation, missing data, outcome measurement, and selective reporting. These are not certified Cochrane reviews. Learn more ↗
CMS Open Payments
Manufacturer payment disclosures are reported via the CMS Sunshine Act. Disclosure is legally required and does not imply bias or misconduct. Language uses "may," "suggests," or "appears" — never definitive clinical claims. CMS Open Payments ↗
Live Clinical Trials
Live from ClinicalTrials.gov · refreshed every 4 hours
Currently enrolling, active, and recently completed studies involving Montelukast Sodium. Data is pulled directly from the U.S. National Library of Medicine.
Recent Research
Live from PubMed · peer-reviewed literature · refreshed every 4 hours
Most recently indexed clinical trials and systematic reviews mentioning Montelukast Sodium in PubMed.
Source Documentation
Structured citations for referenced clinical trials
Each referenced trial is listed with its registry ID, funding source, and bias assessment. Use the copy button to generate a formatted citation.
| Trial | Registry ID | Cite |
|---|---|---|
| CAMP Trial (NIH/Merck) | NCT00393835 | |
| Montelukast in Chronic Asthma | PMID:9665136 | |
| Montelukast Neuropsychiatric Review (2021) | PMID:34019771 |
Bias ratings use Cochrane RoB-2 methodology. Editorial assessment — not a certified Cochrane review.
Our MethodologyMedical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Stopping This Medication Safely
Montelukast does not cause physical dependence. Symptoms may return when stopped. Most importantly: neuropsychiatric symptoms (anxiety, mood changes, aggression, nightmares) often improve dramatically within days of stopping.
What Published Research Shows About Stopping This Medication
This summarizes what published research documents — it is not personal medical advice. Any changes to your medication require discussion with your prescribing physician.
- ·Research shows no pharmacological taper is needed for montelukast
- ·For patients stopping due to neuropsychiatric side effects, research supports immediate discontinuation
- ·Switching to an alternative controller medication (inhaled corticosteroid) before or after stopping is documented in clinical guidelines
- ·Research recommends monitoring respiratory symptoms for the first 2–4 weeks after stopping
Warning Symptoms — Contact Your Doctor If You Experience:
- Suicidal thoughts or self-harm in children — discontinue immediately and seek emergency care
- Severe worsening of asthma or allergic reaction requiring urgent treatment
- Signs of Churg-Strauss (EGPA): rash, nerve pain, worsening symptoms with steroid taper
Never change or stop a medication without consulting your prescribing physician.
Questions for Your Doctor
Questions to Ask
- 1.Has the 2020 FDA black box warning about suicidal thoughts been explained to me/my child?
- 2.Is there a reason to use Singulair specifically over an inhaled corticosteroid, which does not carry neuropsychiatric risks?
- 3.For my child: what behavioral changes should I watch for, and what should I do if I see them?
- 4.Has allergen immunotherapy been discussed as a long-term solution?
- 5.What are the HEPA filtration and trigger-avoidance recommendations for my home environment?
Lab Tests to Request
- Spirometry / peak flow (asthma)
- Allergy skin testing or IgE RAST panel
- Vitamin D level
- Complete allergy trigger assessment
- Behavior/mood baseline documentation before starting (for children)
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Frequently Asked Questions About Singulair®
- What is Singulair® used for?
- Singulair® (Montelukast Sodium) is a Leukotriene Receptor Antagonist manufactured by Merck/Generic. FDA-approved indications include: Asthma (prophylaxis and chronic treatment); Seasonal allergic rhinitis; Exercise-induced bronchoconstriction; Perennial allergic rhinitis (6+ months).
- What are the common side effects of Singulair®?
- Common side effects of Singulair® include: Headache (18%); Neuropsychiatric effects (anxiety, nightmares, agitation) (10–15%); Aggression / behavioral changes (children) (10%); Abdominal pain (4%); Fatigue (3%).
- How much does Singulair® cost?
- Singulair® list price is approximately $250+ (brand historical). With insurance it typically costs $15–30; without insurance approximately $15–30 (generic).
- Who funded the clinical trials for Singulair®?
- Merck funded the pivotal approval trials for Singulair. Neuropsychiatric signals were reported to the FDA as early as 2008, but Merck did not proactively add warnings for 12 years. In 2020, the FDA added the strongest possible black box warning for neuropsychiatric events including suicidal thoughts and actions — for a drug prescribed to children as young as 6 months. A Senate investigation found Merck's internal communications showed awareness of these risks earlier than disclosed.
- How strong is the clinical evidence for Singulair®?
- Key studies: CAMP trial (NIH/Merck), PREVENT study, Merck PEAK trial. Modest improvement in FEV1 (lung function) and allergy symptoms; neuropsychiatric events in 10–20% of pediatric patients based on post-marketing data Potential conflicts of interest: Merck-funded key opinion leaders actively promoted Singulair for mild asthma over cheaper alternatives. The neuropsychiatric signal was downplayed in communications to physicians for years. After the .
- Are there non-drug alternatives to Singulair®?
- Allergen immunotherapy treats root cause; HEPA filtration and anti-inflammatory diet reduce inflammatory burden without any psychiatric side effects See the Alternatives tab for full details.
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