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Montelukast Side Effects

For the Consumer

Applies to montelukast: oral packet, oral tablet, oral tablet chewable

In addition to its needed effects, some unwanted effects may be caused by montelukast. In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking montelukast:

Less common
  • Abdominal or stomach pain
  • bloody nose
  • flu-like symptoms
  • general feeling of discomfort or illness
  • headache
  • joint pain
  • pain or tenderness around the eyes and cheekbones
  • shortness of breath or troubled breathing
  • sweating
  • tightness of the chest
  • trouble with swallowing
  • unusual tiredness or weakness
  • Pus in the urine
Incidence not known
  • Agitation
  • anxiety
  • attempts at killing oneself
  • breathing problems
  • confusion about identity, place, and time
  • constipation
  • fast, irregular, pounding, or racing heartbeat or pulse
  • feeling sad or empty
  • hives or welts
  • indigestion
  • itching, puffiness, or swelling of the eyelids or around the eyes, face, lips, or tongue
  • lack of appetite
  • pains in the stomach, side, or abdomen, possibly moving to the back
  • redness of the skin
  • shaking or trembling of the hands or feet
  • trouble with concentrating
  • unable to sleep
  • unpleasant breath odor
  • upper right abdominal or stomach pain
  • vomiting of blood
  • yellow eyes or skin

Some of the side effects that can occur with montelukast may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Less common
  • Acid or sour stomach
  • belching
  • blurred vision
  • change in near or distance vision
  • dental pain
  • earache
  • heartburn
  • lack or loss of strength
  • pain
  • skin rash, encrusted, scaly and oozing
  • stomach discomfort, upset, or pain
Incidence not known
  • Burning, crawling, itching, numbness, prickling, “pins and needles”, or tingling feelings
  • dreams that are unusual
  • increased tendency to bleed
  • large, flat, blue or purplish patches on the skin
  • muscle aching or cramping
  • sleepiness
  • swollen joints

For Healthcare Professionals

Applies to montelukast: oral granule, oral tablet, oral tablet chewable

Nervous system

Nervous system side effects have included headache (18% to 20%) and dizziness (2%). Isolated and rare reports of somnolence have been associated with the use of higher than recommended doses. Seizures have been reported very rarely. Paresthesias, hypoesthesia, and drowsiness and have been reported in postmarketing experiences.[Ref]


Respiratory system side effects have included influenza (4%), cough (3%), and nasal congestion (2%). In some studies, upper respiratory tract infection (28%) and worsened asthma (4% to 11%) were associated with the use of this drug. However, many patients with asthma have some or all of these symptoms, and a causal relationship has not been proven. Rhinorrhea, sinusitis, otitis, influenza, epistaxis, and pneumonia have also been reported.
Postmarketing reports have included thoracic and mediastinal disorders.[Ref]


Gastrointestinal side effects have included abdominal pain, dyspepsia, or infectious gastroenteritis in up to 3% of patients. Diarrhea has been associated with the use of higher than recommended doses.
Postmarketing reports have included vomiting.[Ref]


In general, montelukast is well tolerated. Asthenia, fatigue, or fever has been associated with the use of this drug in approximately 2% of patients. Varicella has also been reported.[Ref]


Dermatologic side effects have included rash, eczema, urticaria, and dermatitis. Postmarketing experience has included erythema multiform.
Postmarketing reports include Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).[Ref]

Churg-Strauss syndrome has been reported in association with montelukast therapy.[Ref]


Hepatic side effects have included elevated hepatic serum transaminases in approximately 2% of patients. Pancreatitis has been reported very rarely. Jaundice with elevated liver enzymes are described in a 42 year old man several months after starting montelukast therapy. Serum enzymes completely normalized 4 months after drug withdrawal.[Ref]

Postmarketing experience has reported rare cases of cholestatic hepatitis, hepatocellular liver injury and mixed pattern liver injury.[Ref]


Other side effects have included isolated cases of Churg-Strauss syndrome, a rare systemic vasculitis associated with asthma.[Ref]

Churg-Strauss syndrome is a rare granulomatous eosinophilic condition that involves the upper and lower airways and manifests as rhinitis, sinusitis and asthma. If untreated the syndrome may progress to systemic vasculitis, peripheral neuropathy and potentially fatal cardiac complications. In most cases, the condition emerged during withdrawal of oral corticosteroid therapy. A causative role for leukotriene receptor antagonists has not been ruled out.[Ref]


Musculoskeletal side effects have included myalgia, muscle cramps, and muscle aches. Postmarketing experience has reported arthralgia.[Ref]


Hematologic side effects have included increased bleeding tendencies and bruising. Thrombocytopenia has also been reported.[Ref]


Ocular side effects have included conjunctivitis.[Ref]


Psychiatric side effects have included agitation including aggressive behavior and hostility, anxiousness, dream abnormalities and hallucinations, depression, insomnia, irritability, restlessness, suicidal thinking and behavior (including suicide), and tremor.
Postmarketing reports include disorientation, insomnia, and somnambulism.[Ref]


Hypersensitivity side effects have included anaphylaxis, erythema nodosum, pruritus, urticaria, and very rarely hepatic eosinophilic infiltration. Postmarketing reports have included angioedema.[Ref]


Postmarketing reports have included palpitations and edema.


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8. McMorran M "Leukotriene receptor antagonists: suspected adverse reactions." Can Med Assn J 161 (1999): 868-70

9. Minciullo PL, Saija A, Bonanno D, Ferlazzo E, Gangemi S "Montelukast-induced generalized urticaria." Ann Pharmacother 38 (2004): 999-1001

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12. Goldstein MF, Anoia J, Black M "Montelukast-induced hepatitis." Ann Intern Med 140 (2004): 586-7

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14. Price D "Tolerability of montelukast." Drugs 59 (2000): 35-42

15. Wechsler ME, Finn D, Gunawardena D, Westlake R, Barker A, Haranath SP, Pauwels RA, Kips JC, Drazen JM "Churg-Strauss syndrome in patients receiving montelukast as treatment for asthma." Chest 117 (2000): 708-13

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18. Philip G, Hustad C, Noonan G, et al. "Reports of suicidality in clinical trials of montelukast." J Allergy Clin Immunol 124 (2009): 691-696.e6

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20. Sabbagh R, Sheikh-Taha M "Possible montelukast-induced angioedema." Am J Health Syst Pharm 66 (2009): 1705-6

Not all side effects for montelukast may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.