Singulair (Montelukast) is used to prevent and manage asthma symptoms and to relieve the symptoms of seasonal allergies, also known as seasonal allergic rhinitis or hay fever. It works by blocking the effects of leukotrienes, a substance produced by the body in response to certain "triggers" that cause narrowing and swelling of airways in the lungs. Montelukast usually starts to work within one day.

When used to prevent and manage asthma, it is important to understand that montelukast should not be used to relieve an asthma attack once it has started. People with asthma should always have their fast-acting asthma relief medication on hand to treat an asthma attack.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful to people to take this medication if their doctor has not prescribed it.

Singulair (Montelukast) can be taken with or without food.

The oral granules can be given either directly in the mouth or mixed with a spoonful of cold or room temperature soft food (e.g., apple sauce). The packet should not be opened until ready to use. After opening the packet, the full dose of oral granules must be given within 15 minutes. Do not store any oral granule and food mixture for later use. Do not mix the oral granules in liquid. Children may drink liquids after swallowing oral granules.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health.

Contact your doctor if you experience these side effects and they are severe or bothersome.

- Abdominal or stomach pain

- Diarrhea

- Dizziness

- Fever

- Headache

- Scaly and itchy skin

- Skin rash

- Thirst

- Weakness or unusual tiredness

Check with your doctor as soon as possible if any of the following side effects occur:

- Aggressive behavior (such as temper tantrums in children)

- Hyperactivity

- Pounding, fast, or irregular heartbeat

- Persistent or worsening flu-like symptoms, rash, pins and needles, numbness of the arms or legs, joint pain, and severe sinusitis

- Seeing things that are not there (visual hallucinations)

- Signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)

- Signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)

- Signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)

- Tremor

Who should NOT take this medication?

Do not take this medication if you are allergic to montelukast or any ingredients of the medication.

Can you stop Singulair abruptly?

If you stop taking the drug suddenly or don't take it at all: You increase your risk of more frequent and more severe asthma attacks. Asthma that is not treated can lead to increased lung damage. If you have allergies, their symptoms may not be reduced.

Can Singulair make you sleepy?

May cause psychiatric-type effects including agitation, aggressive behavior, anxiety, depression, abnormal dreams, and hallucinations. These have been reported in people of all ages taking Singulair. May cause dizziness or drowsiness and affect a person's ability to drive and operate machinery.