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Singulair 10 mg film-coated tablets

Active Ingredient:
montelukast sodium
Organon Pharma (UK) Limited See contact details
ATC code: 
About Medicine
The Patient Information Leaflet (PIL) is the leaflet included in the pack with a medicine.
Last updated on emc: 03 May 2023

Below is a text only representation of the Patient Information Leaflet (ePIL).

The text only version may be available in large print, Braille or audio CD. For further information call emc accessibility on {phone} 0800 198 5000. The product code(s) for this leaflet is: PL 00025/0358.

Singulair 10mg Tablets

Package leaflet: Information for the user

Singulair® 10 mg film-coated tablets


Read all of this leaflet carefully before you start taking this medicine because it contains important information for you.
  • Keep this leaflet. You may need to read it again.
  • If you have any further questions, ask your doctor or pharmacist.
  • This medicine has been prescribed for you only. Do not pass it on to others. It may harm them, even if their signs of illness are the same as yours.
  • If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. See section 4.

What is in this leaflet

1. What Singulair is and what it is used for
2. What you need to know before you take Singulair
3. How to take Singulair
4. Possible side effects
5. How to store Singulair
6. Contents of the pack and other information

1. What Singulair is and what it is used for
What Singulair is

Singulair is a leukotriene receptor antagonist that blocks substances called leukotrienes.

How Singulair works

Leukotrienes cause narrowing and swelling of airways in the lungs and also cause allergy symptoms. By blocking leukotrienes, Singulair improves asthma symptoms, helps control asthma and improves seasonal allergy symptoms (also known as hay fever or seasonal allergic rhinitis).

When Singulair should be used

Your doctor has prescribed Singulair to treat asthma, preventing your asthma symptoms during the day and night.

  • Singulair is used for the treatment of adults and adolescents 15 years of age and older who are not adequately controlled on their medication and need additional therapy.
  • Singulair also helps prevent the narrowing of airways triggered by exercise.
  • In those asthmatic patients in whom Singulair is indicated in asthma, Singulair can also provide symptomatic relief of seasonal allergic rhinitis.

Your doctor will determine how Singulair should be used depending on the symptoms and severity of your asthma.

What is asthma?

Asthma is a long-term disease.

Asthma includes:

  • difficulty breathing because of narrowed airways. This narrowing of airways worsens and improves in response to various conditions.
  • sensitive airways that react to many things, such as cigarette smoke, pollen, cold air, or exercise.
  • swelling (inflammation) in the lining of airways.

Symptoms of asthma include: Coughing, wheezing, and chest tightness.

What are seasonal allergies?

Seasonal allergies (also known as hay fever or seasonal allergic rhinitis) are an allergic response often caused by airborne pollens from trees, grasses and weeds. The symptoms of seasonal allergies typically may include: stuffy, runny, itchy nose; sneezing; watery, swollen, red, itchy eyes.

2. What you need to know before you take Singulair

Tell your doctor about any medical problems or allergies you have now or have had.

Do not take Singulair
  • if you are allergic to montelukast or any of the other ingredients of this medicine (listed in section 6).

Warnings and precautions

Talk to your doctor or pharmacist before taking Singulair.

  • If your asthma or breathing gets worse, tell your doctor immediately.
  • Oral Singulair is not meant to treat acute asthma attacks. If an attack occurs, follow the instructions your doctor has given you. Always have your inhaled rescue medicine for asthma attacks with you.
  • It is important that you or your child take all asthma medications prescribed by your doctor. Singulair should not be substituted for other asthma medications your doctor has prescribed for you.
  • Any patient on anti-asthma medicines should be aware that if you develop a combination of symptoms such as a flu-like illness, pins and needles or numbness of arms or legs, worsening of pulmonary symptoms, and/or rash, you should consult your doctor.
  • You should not take acetyl-salicylic acid (aspirin) or anti-inflammatory medicines (also known as non-steroidal anti-inflammatory drugs or NSAIDs) if they make your asthma worse.

Patients should be aware that various neuropsychiatric events (for example behaviour and mood-related changes) have been reported in adults, adolescents and children with Singulair (see section 4).

If you develop such symptoms while taking Singulair, you should consult your doctor.

Children and adolescents

Do not give this medicine to children less than 15 years of age.

There are different form(s) of this medicine available for paediatric patients under 18 years of age based on age range.

Other medicines and Singulair

Tell your doctor or pharmacist if you are taking or have recently taken or might take any other medicines including those obtained without a prescription.

Some medicines may affect how Singulair works, or Singulair may affect how other medicines work.

Tell your doctor if you are taking the following medicines before starting Singulair:

  • phenobarbital (used for treatment of epilepsy)
  • phenytoin (used for treatment of epilepsy)
  • rifampicin (used to treat tuberculosis and some other infections)
  • gemfibrozil (used for treatment of high lipid levels in plasma)

Singulair with food and drink

Singulair 10 mg film-coated tablet may be taken with or without food.

Pregnancy and breast-feeding

If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking Singulair.


Your doctor will assess whether you can take Singulair during this time.


It is not known if Singulair appears in breast milk. You should consult your doctor before taking Singulair if you are breast-feeding or intend to breast-feed.

Driving and using machines

Singulair is not expected to affect your ability to drive a car or operate machinery. However, individual responses to medication may vary. Certain side effects (such as dizziness and drowsiness) that have been reported with Singulair may affect some patients’ ability to drive or operate machinery.

Singulair 10 mg film-coated tablets contain lactose and sodium

If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicinal product.

This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially ‘sodium-free’.

3. How to take Singulair

Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.

  • You should take only one tablet of Singulair once a day as prescribed by your doctor.
  • It should be taken even when you have no symptoms or have an acute asthma attack.

For adults and adolescents 15 years of age and older:

The recommended dose is one 10 mg tablet to be taken daily in the evening.

If you are taking Singulair, be sure that you do not take any other products that contain the same active ingredient, montelukast.

This medicine is for oral use.

You can take Singulair 10 mg with or without food.

If you take more Singulair than you should

Contact your doctor immediately for advice.

There were no side effects reported in the majority of overdose reports. The most frequently occurring symptoms reported with overdose in adults and children included abdominal pain, sleepiness, thirst, headache, vomiting, and hyperactivity.

If you forget to take Singulair

Try to take Singulair as prescribed. However, if you miss a dose, just resume the usual schedule of one tablet once daily.

Do not take a double dose to make up for a forgotten dose.

If you stop taking Singulair

Singulair can treat your asthma only if you continue to take it.

It is important to continue taking Singulair for as long as your doctor prescribes. It will help control your asthma.

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4. Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

In clinical studies with Singulair 10 mg film-coated tablets, the most commonly reported side effects (may affect up to 1 in 10 people) thought to be related to Singulair were:

  • abdominal pain
  • headache

These were usually mild and occurred at a greater frequency in patients treated with Singulair than placebo (a pill containing no medication).

Serious side effects

Talk with your doctor immediately if you notice any of the following side effects, which may be serious, and for which you may need urgent medical treatment.

Uncommon: the following may affect up to 1 in 100 people

  • allergic reactions including swelling of the face, lips, tongue, and/or throat which may cause difficulty in breathing or swallowing
  • behaviour and mood related changes: agitation including aggressive behaviour or hostility, depression
  • seizure

Rare: the following may affect up to 1 in 1,000 people

  • increased bleeding tendency
  • tremor
  • palpitations

Very rare: the following may affect up to 1 in 10,000 people

  • combination of symptoms such as flu-like illness, pins and needles or numbness of arms and legs, worsening of pulmonary symptoms and/or rash (Churg-Strauss syndrome) (see section 2)
  • low blood platelet count
  • behaviour and mood related changes: hallucinations, disorientation, suicidal thoughts and actions
  • swelling (inflammation) of the lungs
  • severe skin reactions (erythema multiforme) that may occur without warning
  • inflammation of the liver (hepatitis)

Other side effects while the medicine has been on the market

Very common: the following may affect more than 1 in 10 people

  • upper respiratory infection

Common: the following may affect up to 1 in 10 people

  • diarrhoea, nausea, vomiting
  • rash
  • fever
  • elevated liver enzymes

Uncommon: the following may affect up to 1 in 100 people

  • behaviour and mood related changes: dream abnormalities, including nightmares, trouble sleeping, sleepwalking, irritability, feeling anxious, restlessness
  • dizziness, drowsiness, pins and needles/numbness
  • nosebleed
  • dry mouth, indigestion
  • bruising, itching, hives
  • joint or muscle pain, muscle cramps
  • bedwetting in children
  • weakness/tiredness, feeling unwell, swelling

Rare: the following may affect up to 1 in 1,000 people

  • behaviour and mood related changes: disturbance in attention, memory impairment, uncontrolled muscle movements

Very rare: the following may affect up to 1 in 10,000 people

  • tender red lumps under the skin, most commonly on your shins (erythema nodosum)
  • behaviour and mood related changes: obsessive-compulsive symptoms, stuttering

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Singulair
  • Keep this medicine out of the sight and reach of children.
  • Do not use this medicine after the expiry date which is stated on the blister after EXP. The first two numbers indicate the month; the last four numbers indicate the year. The expiry date refers to the last date of that month.
  • Store in the original package in order to protect from light and moisture.
  • Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.

6. Contents of the pack and other information
What Singulair contains
  • The active substance is montelukast. Each tablet contains montelukast sodium which corresponds to 10 mg of montelukast.
  • The other ingredients are:
    Microcrystalline cellulose, lactose monohydrate (89.3 mg), croscarmellose sodium, hyprolose (E 463), and magnesium stearate.
    Film coating: hypromellose, hyprolose (E 463), titanium dioxide (E 171), red and yellow ferric oxide (E 172), and carnauba wax.

What Singulair looks like and contents of the pack

10 mg Singulair tablets are beige, rounded square, film-coated with SINGULAIR engraved on one side, MSD 117 on the other.

Blisters in packages of: 7, 10, 14, 20, 28, 30, 50, 56, 84, 90, 98, 100, 140, and 200 tablets.

Blisters (unit dose), in packages of: 49x1, 50x1 and 56x1 tablets

Not all pack sizes may be marketed.

Marketing Authorisation Holder and Manufacturer

The Marketing Authorisation Holder:

Organon Pharma (UK) Limited
The Hewett Building
14 Hewett Street
United Kingdom

The manufacturer:

Organon Pharma (UK) Limited
Shotton Lane
NE23 3JU

Information is given by:

Asthma UK
18 Mansell Street
E1 8AA

Alternatively phone the Asthma UK Helpline on 0300 222 5800, Monday to Friday, 9 am to 5 pm.

(Asthma UK is an independent charity working to conquer asthma and is not associated with Organon Pharma (UK) Limited.)

This medicinal product is authorised in the Member States of the EEA under the following names:

Austria, Belgium, Denmark, Finland, France, Greece, Spain, Sweden, Germany, Ireland, United Kingdom, Italy, Luxemburg, Netherlands, Portugal Singulair

This package leaflet was last revised in December 2022

© 2022 Organon group of companies. All rights reserved.


Organon Pharma (UK) Limited
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The Hewett Building, 14 Hewett Street, London, EC2A 3NP, UK
+44 (0) 208 159 3593
Medical Information e-mail
[email protected]
Customer Care direct line
+44 (0) 208 159 3500