Singulair is a once daily medication, taken usually in the evening before bedtime, that helps control asthma and allergies. Maintaining a daily dosage journal when on Singulair can benefit the patient and their doctor when the journal also contains details about symptoms that flare up or subside while on the medication. It is also helpful to log in the journal the dosage amount and time of dose each and every day; and even logging forgotten doses if that occurs so all relevant information about the medication and its effectiveness is in one location.