generic for Singulair

Montelukast Side Effects

See also Warning section.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: numbness/tingling/shooting pain in the arms or legs, sinus pain/swelling, muscle weakness, uncontrolled muscle movements, stuttering.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
  • infectious gastroenteritis
  • chickenpox
  • viral infection
  • thrombocytopenic disorder
  • eosinophilia
  • acute confusion
  • obsessive-compulsive disorder
  • suicidal
  • suicidal ideation
  • stuttering
  • motor tic disorder
  • nightmares
  • agitation
  • depression
  • aggressive behavior
  • hostility
  • myopia
  • conjunctivitis
  • acute bacterial otitis media
  • hypersensitivity angiitis
  • pharyngitis
  • laryngitis
  • upper respiratory infection
  • sinusitis
  • nasal congestion
  • pneumonia
  • influenza
  • bronchitis
  • eosinophilic pneumonia
  • toothache
  • dyspepsia
  • gastroenteritis
  • hepatocellular damage
  • skin and skin structure infection
  • atopic dermatitis
  • eczema
  • erythema multiforme
  • toxic epidermal necrolysis
  • Stevens-Johnson syndrome
  • erythema nodosum
  • pruritus of skin
  • urticaria
  • arthralgia
  • myalgia
  • cramps
  • drowsy
  • memory impairment
  • hallucinations
  • seizure disorder
  • dizziness
  • insomnia
  • fever
  • fatigue
  • tremor
  • hypesthesia
  • skin rash
  • edema
  • headache disorder
  • epistaxis
  • palpitations
  • cough
  • nausea
  • vomiting
  • diarrhea
  • urinary incontinence
  • pyuria
  • abnormal hepatic function tests
  • nervousness
  • bruising
  • angioedema
  • hypersensitivity drug reaction
  • paresthesia
  • cholestatic hepatitis
  • rhinorrhea
  • general weakness
  • irritability
  • night terror
  • acute abdominal pain
  • pancreatitis
  • otitis
  • dream disorder
  • sleep walking disorder
  • disturbance of attention
  • symptoms of anxiety

Drug Interactions

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.