Montelukast is the generic version of Singulair. They contain the same active ingredient, montelukast sodium, and work identically in your body. The only real differences are price, manufacturer, and the inactive ingredients used to form the tablet.
Same Drug, Different Label
Singulair is the brand name originally developed and marketed by Merck. Montelukast is the generic name for the active compound in that medication. When you pick up a generic montelukast prescription, you’re getting the same drug at the same strength. The FDA requires generics to be bioequivalent to the brand, meaning they must deliver the same amount of active ingredient into your bloodstream at the same rate.
Both versions come in the same formulations: a 10 mg tablet for adults, 4 mg and 5 mg chewable tablets for children, and 4 mg oral granules for the youngest patients. Your pharmacist will typically dispense whichever version your insurance covers or whichever is cheapest.
The Price Gap Is Significant
Generic montelukast costs roughly $0.14 per 10 mg tablet. Brand-name Singulair runs about $9.69 per tablet at the same dose. That’s nearly 70 times more expensive. For most people, there’s no clinical reason to pay for the brand name. The one scenario where switching between manufacturers could matter is if you have a rare sensitivity to a specific inactive ingredient, since the fillers, colorings, and coatings differ between brand and generic versions.
For example, Singulair’s chewable tablets contain aspartame and cherry flavoring, which produce small amounts of phenylalanine. People with phenylketonuria (a metabolic condition) need to know this. Generic versions may use different fillers entirely, so checking the label matters if you have known sensitivities.
What Montelukast Does
Your immune system releases chemicals called leukotrienes when it encounters allergens, cold air, or exercise. These chemicals latch onto receptors in your airways and trigger inflammation, mucus production, and narrowing of the air passages. Montelukast blocks those receptors so leukotrienes can’t bind to them, which prevents the chain reaction before it starts.
This mechanism makes it useful for several conditions. It’s FDA-approved for ongoing asthma management in patients 12 months and older, prevention of exercise-triggered breathing difficulty in those 6 and older, seasonal allergies in patients 2 and older, and year-round allergies in patients as young as 6 months. It starts working within about a day for asthma symptoms, though a full trial of 4 to 8 weeks is typical before deciding whether it’s effective enough.
The Boxed Warning Both Versions Carry
In 2020, the FDA added its strongest possible warning to all montelukast products, brand and generic alike. The warning addresses serious mental health side effects, including suicidal thoughts, that have been reported in some patients. Because of this, the FDA now recommends montelukast only be used for allergies when other treatments haven’t worked or aren’t tolerated. For asthma, it remains an option when the benefits outweigh the risks.
The mood and behavior changes to watch for include agitation, hostility, depression, anxiety, confusion, vivid or bad dreams, hallucinations, trouble sleeping, sleepwalking, memory problems, obsessive-compulsive symptoms, and restlessness. Less commonly reported effects include tremor, stuttering, and uncontrolled muscle movements. These side effects apply equally to Singulair and every generic version, since they’re caused by the active drug itself, not anything specific to one manufacturer’s formulation.
If you or your child notice any of these changes after starting the medication, stop taking it and contact your prescriber promptly.
Switching Between Brand and Generic
If you’ve been taking Singulair and your pharmacy switches you to generic montelukast (or vice versa), you should not notice any difference in how well the medication works. The active ingredient and dose are the same. Occasionally, people report that a switch feels different, which can sometimes be traced to differences in how quickly a particular generic tablet dissolves, or to the placebo effect of seeing an unfamiliar pill. If symptoms genuinely worsen after a switch, it’s worth mentioning to your pharmacist, who can check whether a different generic manufacturer’s version is available.