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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.

Major Side Effects

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

Minor Side Effects

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


The most common adverse reactions (incidence more than 5% and greater than placebo) were: Upper respiratory infection, fever, headache, pharyngitis, cough, abdominal pain, diarrhea, otitis media, influenza, rhinorrhea, sinusitis, otitis.[Ref]


Very rare (less than 0.01%): Churg-Strauss Syndrome[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]

Nervous system

Very common (10% or more): Headache (18.4%)
Common (1% to 10%): Dizziness (1.9%)
Postmarketing reports: Disturbance in attention, irritability, memory impairment, tremor, drowsiness, paraesthesia/hypoesthesia, seizures[Ref]


Common (1% to 10%): Rash (1.6%), atopic dermatitis, skin infection, eczema, urticaria
Postmarketing reports: Angioedema, bruising, erythema multiforme, erythema nodosum, pruritus, Stevens-Johnson syndrome/toxic epidermal necrolysis[Ref]


Common (1% to 10%): Abdominal pain (2.9%), dyspepsia (2.1%), dental pain (1.7%), gastroenteritis (1.5%), nausea, diarrhea, dyspepsia, gastroenteritis, tooth infection[Ref]


Common (1% to 10%): ALT increase (2.1%), AST increased (1.6%)
Postmarketing reports: Hepatic eosinophilic infiltration; cases of cholestatic hepatitis, hepatocellular liver-injury, and mixed-pattern liver injury. Most of these occurred in combination with other confounding factors, such as use of other medications, or when administered to patients who had underlying potential for liver disease such as alcohol use or other forms of hepatitis.[Ref]


Common (1% to 10%): Myopia, conjunctivitis[Ref]


Common (1% to 10%): Asthenia, fatigue (1.8%), fever (1.5%), trauma (1%), influenza, fever, otitis, viral infection, varicella, ear pain, otitis media
Uncommon (0.1% to 1%): Malaise
Postmarketing reports: Edema[Ref]


Common (1% to 10%): Influenza (4.2%), cough (2.7%), nasal congestion (1.6%), pharyngitis, sinusitis, laryngitis, infective rhinitis, acute bronchitis, rhinorrhea, pneumonia, upper respiratory infection, wheezing, tonsillitis
Postmarketing reports: Epistaxis, pulmonary eosinophilia[Ref]


Postmarketing reports: Palpitations[Ref]


Postmarketing reports: Enuresis in children[Ref]


Postmarketing reports: Increased bleeding tendency, thrombocytopenia[Ref]


Postmarketing reports: Anaphylaxis[Ref]


Postmarketing reports: Arthralgia, myalgia including muscle cramps[Ref]


Postmarketing reports: Agitation including aggressive behavior or hostility, anxiousness, depression, disorientation, dream abnormalities, hallucinations, insomnia, restlessness, somnambulism, suicidal thinking and behavior (including suicide)[Ref]


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

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23. 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

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.