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Are you taking Montelukast for asthma or allergies? Here is everything you need to know about how it works, potential side effects, and why mental health monitoring is so critical.

Dr. Priya Sammani (MBBS)
Medically Reviewed by Dr. Priya Sammani (MBBS) ✓ Medically Reviewed
📅 Updated: Oct 21, 2026 • ⏱ 9 min read • Editorial Policy
Are you taking Montelukast for asthma or allergies? Here is everything you need to know about how it works, potential side effects, and why mental health monitoring is so critical.
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Do you or a loved one take Montelukast for asthma or pesky seasonal allergies? This common prescription medicine helps millions of people breathe easier every single day. But do you truly know how it works in your body or what signs to watch out for while taking it?

Understanding your prescription is one of the most powerful steps you can take for your health. Let us walk through everything you need to know about Montelukast in simple, plain English.

Key Takeaways at a Glance

  • Daily Prevention Only: Montelukast prevents asthma and allergy symptoms; it does not stop sudden attacks.
  • Keep Your Inhaler Close: Always carry your fast-acting rescue inhaler for sudden breathing trouble.
  • Monitor Mental Health: Watch for sudden mood changes, depression, or unusual thoughts while taking this medicine.
  • Consistency Matters: Take your tablet at the exact same time every day, exactly as your doctor instructed.
  • Talk to Your Doctor: Share a full list of your other medicines and health history before starting.
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What is Montelukast?

Simply put, Montelukast is a prescription medicine used to prevent and treat asthma and allergy symptoms. It blocks specific natural substances in your body called leukotrienes that cause your airways to swell and tighten. By stopping this swelling, the medicine makes breathing much easier for you.

You will often see this medicine sold under the brand name Singulair. It comes in oral tablet form and is widely prescribed by doctors around the world for both adults and children.

Crucial Safety Note:

You must never use Montelukast to treat a sudden, acute asthma attack. It does not work fast enough to open a closing airway during an emergency. Always keep your quick-relief rescue inhaler nearby for sudden breathing flare-ups.

Things to Tell Your Doctor Before Starting This Medicine

Before your doctor prescribes Montelukast, they need a complete picture of your medical history. Sharing your full health background ensures this medicine is safe and appropriate for your specific lifestyle and body.

You must tell your doctor right away if any of the following situations apply to you:

  • You have a history of liver disease or impaired liver function.
  • You have had an allergic reaction to Montelukast, aspirin, dyes, or any other medicines.
  • You are currently pregnant, planning to become pregnant soon, or trying to start a family.
  • You are breastfeeding a baby or nursing a young child.

Your doctor will review these details carefully. Based on your answers, they can decide if Montelukast is the right choice for your breathing care plan.

How to Use This Medicine Properly

For any medicine to work effectively, you must use it exactly as directed by your doctor. Following instructions prevents complications and maximizes your relief.

  • Swallow your tablet whole with a full glass of water.
  • Try to take your medicine at the exact same time every single day. Your doctor will tell you whether morning or night is best for you.
  • You can take this medicine with food or on an empty stomach. If it upsets your stomach, try taking it with a small meal.
  • Keep taking your medicine every day even if you feel completely fine, unless your doctor tells you to stop.
  • If you give this medicine to a child, follow pediatric dosage instructions carefully and never guess the amount.
  • Never share your prescription medicine with friends or family members, even if they have similar symptoms.

What should you do if you take too much?

If you think you or your child took more than the prescribed dose, do not panic, but do not ignore it either. Call your local emergency services or poison control center right away, or go straight to the nearest hospital emergency department.

What should you do if you miss a dose?

If you forget to take your pill at the usual time, simply skip that missed dose. Wait and take your next tablet at your normal scheduled time. Never take two doses at the same time to make up for a missed one.

Other Medicines That May Interact

Some medicines can change how Montelukast works in your body. Tell your doctor about every prescription drug, over-the-counter pill, vitamin supplement, and herbal product you take.

Medicine Category Common Examples
Seizure or epilepsy medicines Phenytoin, Phenobarbital, Carbamazepine
Certain antibiotic treatments Rifabutin, Rifampin

Things to Watch While Taking This Medicine

While taking Montelukast, pay close attention to how your body and mind feel. Staying aware helps you catch minor issues before they become serious problems.

Special Attention to Mental Health!

This is the single most important warning regarding Montelukast. Some people who take this medicine experience unexpected shifts in mood, behavior, and mental well-being. You and your family members should watch out for any unusual emotional changes.

  • Sudden feelings of nervousness, worry, or severe anxiety.
  • Feeling restless, agitated, or unusually irritable over small things.
  • New or worsening feelings of deep sadness or clinical depression.
  • Trouble falling asleep, staying asleep, or having vivid, scary nightmares.
  • Sudden aggressive outbursts, hostility, or unfriendly behavior.
  • Thoughts of self-harm, hurting others, or suicide.

Emergency Mental Health Warning:

If you or a family member notices any mood changes—especially thoughts of self-harm or suicide—take it very seriously. Contact your doctor right away or go to the nearest emergency room right away.

Possible Side Effects

Like all medicines, Montelukast can cause side effects, though not everyone experiences them. Some side effects are mild and go away on their own. This others require immediate medical attention.

Side Effect Type Description and Details
Serious Side Effects (Call Your Doctor Right Away)
Severe Allergic Reactions Rash, hives, itching, or swelling of your face, lips, tongue, or throat.
Mental Health Shifts Anxiety, depression, agitation, or thoughts of harming yourself.
Flu-Like Illness Fever, body aches, persistent cough, headache, and severe tiredness.
Nerve Sensations Pain, numbness, tingling, or a crawling sensation in your hands or feet.
Common Mild Side Effects (Report If They Persist)
Common Symptoms Mild headache, stomach ache, diarrhea, sore throat, or a runny nose.

How to Store and Dispose of Your Medicine

Proper storage keeps your medicine safe, potent, and effective throughout its shelf life.

  • Keep all medicines completely out of reach of young children and household pets.
  • Store your tablets at room temperature, ideally between 15°C and 30°C (59°F to 86°F).
  • Keep your medicine away from excess heat, bright light, and moisture. Do not store pill bottles in humid bathrooms.
  • Make sure the container lid is tightly closed after every use.
  • Never take tablets past their printed expiration date.

When you have leftover or expired pills, dispose of them safely so they do not harm the environment or animals. Do not flush pills down the toilet unless the label specifically instructs you to do so. If you are unsure, ask your pharmacist for guidance. The safest household disposal method is mixing unwanted pills with used coffee grounds or cat litter, sealing them inside a plastic bag, and placing them in your household trash bin.

💡 Take-Home Message

  • Montelukast is a daily preventive medicine for asthma and allergies. It cannot stop a sudden asthma attack.
  • Always keep your fast-acting rescue inhaler close by for unexpected breathing emergencies.
  • Monitor your mental health closely. Report any sudden mood changes, depression, or thoughts of self-harm to your doctor right away.
  • Disclose all other medicines, supplements, and health conditions to your doctor before starting treatment.
  • Keep taking your tablets exactly as prescribed, even when your symptoms disappear.

Sources & References:
1. Cleveland Clinic. Montelukast (Singulair): Uses, Side Effects & Dosages. Available from: https://my.clevelandclinic.org
2. Mayo Clinic. Montelukast (Oral Route) Proper Use and Precautions. Available from: https://www.mayoclinic.org
3. NHS UK. Montelukast for Asthma and Allergies. Available from: https://www.nhs.uk
4. U.S. Food and Drug Administration (FDA). Safety Announcements on Montelukast Neuropsychiatric Events. Available from: https://www.fda.gov
5. National Institutes of Health (NIH) / PubMed. Leukotriene Receptor Antagonists in Clinical Practice. DOI: 10.1016/j.chest.2020.05.551

❓ FAQ

Frequently Asked Medical Questions (FAQ)

Evidence-based clinical answers to common patient questions

Can I take Montelukast if I have a sudden asthma attack?

No, Montelukast is designed for long-term daily prevention and does not work fast enough to stop an active asthma attack. You should always use your quick-relief rescue inhaler for sudden breathing emergencies.

What time of day is best to take my Montelukast tablet?

You should take your tablet at the exact same time every single day. Many doctors recommend taking it in the evening, especially for patients whose asthma symptoms flare up at night.

What mental health side effects should I watch for?

Watch for sudden anxiety, agitation, aggression, vivid nightmares, new depression, or thoughts of self-harm. Contact your doctor right away if you notice any changes in your mood.

Can I stop taking Montelukast if my allergy symptoms go away?

No, you should keep taking your medicine daily even when you feel well. Stopping abruptly can cause your asthma or allergy symptoms to return. Always consult your doctor before stopping.

Is it safe to drink alcohol while taking Montelukast?

Moderate alcohol use usually does not interact directly with Montelukast, but alcohol can trigger asthma symptoms in some people. It is best to discuss your alcohol habits with your doctor.

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