 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  do not work well.This medication must be used regularly to be effective. It does not work right away and should not be used to relieve sudden asthma attacks or breathing problems. If an asthma attack or sudden shortness of breath occurs, use your quick-relief inhaler as prescribed.This drug works by blocking certain natural substances (leukotrienes) that may cause or worsen asthma and allergies. It helps make breathing easier by reducing swelling (inflammation) in the airways. How to use Singulair oral Read the Medication Guide provided by your pharmacist before you start taking montelukast and each time you get a refill. If you have any questions, ask your doctor or pharmacist. Take this medication by mouth with or without food as directed by your doctor. The dosage is based on your age and medical condition. If you are using the chewable tablets, chew them thoroughly before swallowing. If your child cannot safely chew and swallow them, consult the doctor or pharmacist for advice. Take this medication at the same time each day. If you are taking this medication for asthma or for both asthma and allergies, take your dose in the evening. If you are taking montelukast to prevent only allergies, take your dose either in the </s>