It can also relieve symptoms of seasonal allergies and indoor and outdoor allergies, and it can prevent exercise-induced bronchospasm in adults and children aged 6 years or more.
The drug is available in granules for infants aged 12 to 23 months, a cherry-flavored chewable tablet for children aged 24 months to 14 years, and a tablet that can be swallowed whole. The dose starts at 4 milligrams for infants, rising to 10 milligrams for those aged 15 and over.
How does it work?
Singulair can offer protection or relief from asthma and allergy symptoms.
Singulair blocks the action of leukotrienes.
Leukotrienes are fatty signaling molecules that the body produces when there is inflammation.
They are thought to play a key role in triggering the symptoms of asthma and hay fever. They contribute to the pathophysiology of asthma, causing inflammation and swelling in the airways, airflow obstruction, increased secretion of mucus, mucosal accumulation, and bronchoconstriction.
When asthma triggers, such as pollen, are inhaled, the body reacts by releasing leukotrienes.
Leukotrienes cause the lungs and airways to become red and swollen. The airway muscles tighten, resulting in asthma symptoms, including shortness of breath, wheezing, and coughing.
Singulair blocks the action of leukotrienes. It either prevents or reduces:
- Muscle contractions in the airway
- Inflammation and redness in the airways
- Asthma symptoms.
Leukotrienes also cause symptoms of allergy, such as hay fever, so Singulair is also effective for relieving hay fever symptoms.
The producers of Singulair say that it should be taken once a day, in the evening.
For people who are using it to prevent exercise-induced asthma, it should be taken 2 hours before exercise, and they should keep a rescue inhaler with them in case it is needed. They should not take an additional dose if they are already taking a daily dose.
Patients are advised to speak to their doctor before using Singulair to prevent asthma during activity.
Singulair does not act fast enough to deal with an asthma attack straight away, so it should not be used for a sudden asthma attack. A rescue inhaler should be used in this case.
The most common side effects include:
- Ear infection
- Sinus infection
- Sore throat
- Stomach pain
- Upper respiratory infection.
Other symptoms that should be reported to a doctor include a skin rash or hives, bruising, pain or muscle weakness, bleeding, and red or pinpoint spots under the skin.
Singulair has been linked to behavior and mood changes, hostility, aggression, agitation, vivid and unpleasant dreams, confusion, anxiety, hallucinations, sleepwalking, suicidal thoughts and actions, insomnia, tremor, and depression. Instances of this have been highlighted in the media.
The United States Food and Drug Administration (FDA) noted in 2015 that the manufacturers of the drug issued an early warning in 2008, and that investigations were under way into the complaints.
The FDA cautions people not to stop taking Singulair without first discussing this with their health care provider.
The Therapeutic Goods Administration in Australia reported 58 cases of neuropsychiatric adverse events between 2000 and 2013.
The FDA is still gathering information about these effects, but the number of possible reactions is very small compared with the number of doses taken each day worldwide, so it is not yet possible to establish a definite cause and effect.
Parents are cautioned to watch for changes in behavior.
Additional side effects include, rarely, a possible increase in certain white blood cells, and the risk of blood vessels becoming inflamed throughout the body. This can lead to numbness and tingling, flu-like symptoms, a rash, and inflamed sinuses.
If asthma symptoms get worse, if attacks become more severe, or if side effects occur, these should be reported to the doctor.
If Singulair triggers an allergic reaction, it is important to seek medical advice at once.
The cherry chewable tablets contain a component of aspartame known as phenylalanine. If a person could have a reaction to this substance, they should not use Singulair.