Skip to Content

UK Edition. Click here for US version.


View full screen / Print PDF » Download PDF ⇩
Singulair® 10mg Film-coated Tablets
(montelukast sodium)
Your medicine is known by the above name, but will be referred to as
Singulair throughout this:
Patient Information Leaflet

• 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.

Read all of this leaflet carefully before you start taking this medicine.
• Keep this leaflet. You may need to read it again.
• If you have any further questions, please ask your doctor or pharmacist.
• This medicine has been prescribed for you. Do not pass it on to others. It may
harm them, even if their symptoms are the same as yours.
• If any of the side effects get serious, or if you notice any side effects not listed
in this leaflet, please tell your doctor or pharmacist.

• Any patient on anti-asthma medicines should be aware that if you develop
a combination of symptoms such as 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.

In this leaflet:
1) What Singulair is and what it is used for
2) Before you take Singulair
3) How to take Singulair
4) Possible side effects
5) How to store Singulair
6) Further information

Use in children
For children 2 to 5 years old, Singulair Paediatric 4 mg chewable tablets
and SINGULAIR Paediatric 4 mg granules are available.
For children 6 to 14 years old, Singulair Paediatric 5 mg chewable tablets
are available.

1) What Singulair is and what it is used for

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

Singulair is a leukotriene receptor antagonist that blocks substances called
leukotrienes. 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).
Your doctor has prescribed Singulair to treat asthma, preventing your
asthma symptoms during the day and night.
• Singulair is used for the treatment of patients who are not adequately
controlled on their medication and need additional therapy.
• Singulair also helps to prevent the narrowing of airways triggered by
• In those asthmatic patients in whom Singulair is indicated in asthma,
Singulair can also provide symptomatic relief of seasonal allergic

Please tell your doctor or pharmacist if you are taking or have recently
taken other medicines, including those obtained without a prescription.
Tell your doctor if you are taking the following medicines before starting
• 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)
Taking Singulair with food and drink
Singulair 10 mg may be taken with or without food.
Pregnancy and breast-feeding

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 the 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.

Use in pregnancy
Women who are pregnant or intend to become pregnant should consult
their doctor before taking Singulair. Your doctor will assess whether you can
take Singulair during this time.
Use in breast-feeding
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 breastfeed.
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
very rarely with Singulair may affect some patients’ ability to drive or
operate machinery.

2) Before you take Singulair

Important information about some of the ingredients of Singulair
Singulair 10 mg film-coated tablets contain lactose. If you have been told by
your doctor that you have an intolerance to some sugars, contact your
doctor before taking this medicinal product.

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

3) How to take Singulair

Take special care with Singulair
• If your asthma or breathing gets worse, tell your doctor immediately.

• 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.
• Always take Singulair as your doctor has told you. You should check with
your doctor or pharmacist if you are not sure.
• To be taken by mouth

• 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.

For adults and adolescents 15 years of age and older:
One 10 mg tablet to be taken daily in the evening. Singulair 10 mg may be
taken with or without food.

Do not take Singulair if you
• are allergic (hypersensitive) to montelukast or any of the other ingredients
of Singulair (see 6. Further information).

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

In asthmatic patients treated with montelukast, very rare cases of a
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) have been reported. You must tell your doctor
right away if you get one or more of these symptoms.
Ask your doctor or pharmacist for more information about side effects. If any
of the side effects gets serious, or if you notice any side effects not listed in
this leaflet, please tell your doctor or pharmacist.
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: By reporting side effects you can help
provide more information on the safety of this medicine.

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

5) How to store Singulair
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 product, ask your doctor
or pharmacist.

4) Possible side effects
Like all medicines, Singulair 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 (occurring in at least 1 of 100 patients and
less than 1 of 10 patients treated) 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).
The frequency of possible side effects listed below is defined using the
following convention:
Very common (affects at least 1 user in 10)
Common (affects 1 to 10 users in 100)
Uncommon (affects 1 to 10 users in 1,000)
Rare (affects 1 to 10 users in 10,000)
Very rare (affects less than 1 user in 10,000)
Additionally, while the medicine has been on the market, the following have
been reported:
• upper respiratory infection (Very common)
• increased bleeding tendency (Rare)
• allergic reactions including rash, swelling of the face, lips, tongue,
and/or throat which may cause difficulty in breathing or swallowing
• behaviour and mood related changes [dream abnormalities, including
nightmares, trouble sleeping, sleep walking, irritability, feeling anxious,
restlessness, agitation including aggressive behaviour or hostility,
depression (Uncommon); tremor, disturbance in attention, memory
impairment (Rare); hallucinations, disorientation, suicidal thoughts and
actions (Very rare)]
• dizziness, drowsiness, pins and needles/numbness, seizure
• palpitations (Rare)
• nosebleed (Uncommon) swelling (inflammation) of the lungs (very rare)
• diarrhoea, nausea, vomiting (Common); dry mouth, indigestion
• hepatitis (inflammation of the liver) (Very rare)
• rash (Common); bruising, itching, hives (Uncommon); tender red lumps
under the skin most commonly on your shins (erythema nodosum),
severe skin reactions (erythema multiforme) that may occur without
warning (Very rare)

joint or muscle pain, muscle cramps (Uncommon)
• fever (Common); weakness/tiredness, feeling unwell, swelling

• Keep all medicines out of the sight and reach of children.
• Do not use this medicine after the date shown by the six numbers
following EXP on the blister. The first two numbers indicate the month; the
last four numbers indicate the year. This medicine expires at the end of
the month shown.
• Do not store above 30°C. Store in the original package. Protect from light
and moisture.
• If the tablets become discoloured or show any other signs of deterioration,
you should seek the advice of your pharmacist who will tell you what to
• Medicines should not be disposed of via wastewater or household waste.
Ask your pharmacist how to dispose of medicines no longer required.
These measures will help to protect the environment.

6) Further information
What Singulair contains:
The active ingredient is montelukast.
Each tablet contains montelukast sodium which corresponds to 10 mg of
Each tablet also contains lactose monohydrate (89.3mg), microcrystalline
cellulose, magnesium stearate, hydroxypropylcellulose (E 463) and
croscarmellose sodium.
Film coating: hydroxypropylcellulose (E 463), red and yellow ferric oxide
(E172), hypromellose, titanium dioxide (E171) and carnauba wax.
What Singulair looks like and contents of the pack
Singulair 10mg Film-coated Tablets are biege, round square, biconvex with
‘MSD 117’ engraved on one side and “Singulair” on the other.
Singulair 10mg Film-coated Tablets are available as blister packs of 28
PL 10383/1930

Singulair 10mg Film-coated Tablets


Who makes and repackages your medicine?
Your medicine is manufactured by Merck Sharp & Dohme Ltd., Cramlington
Northumberland NE23 3JU. Procured from within the EU and repackaged
by Product Licence Holder: Primecrown Ltd, 4/5 Northolt Trading Estate,
Belvue Road, Northolt, Middlesex, UB5 5QS.
Leaflet date: 14.07.2015
Further information about asthma is available in the UK from:
Asthma UK, Providence House, Providence Place, London N1 ONT.
Alternatively phone the Asthma UK Adviceline on 08457 010203, Monday to
Friday 9 am to 5 pm, calls charged at local rate.
(Asthma UK is an independent charity working to conquer asthma and are
not associated with Merck Sharp & Dohme Limited or Primecrown Ltd.)
Singulair® is a registered trademark of Merck & Co., Inc., Whitehouse
Station, NJ, USA.

Expand view ⇕

Source: Medicines and Healthcare Products Regulatory Agency

Disclaimer: Every effort has been made to ensure that the information provided here is accurate, up-to-date and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This information has been compiled for use by healthcare practitioners and consumers in the United States. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate that the drug or combination is safe, effective or appropriate for any given patient. If you have questions about the substances you are taking, check with your doctor, nurse or pharmacist.