Montelukast Side Effects: What You Need to Know

Montelukast (brand name Singulair) is a popular pill for asthma and allergic rhinitis. It works by blocking leukotrienes, chemicals that cause airway swelling. Most people feel better on it, but like any drug, it can bring unwanted reactions. Below is a quick guide to the side effects you might see and how to handle them.

Common Montelukast Side Effects

The most frequently reported complaints are mild and often go away on their own. Expect some of these:

• Headache – a dull throb that usually fades after a few days.
• Stomach upset – nausea, mild abdominal pain, or occasional diarrhea.
• Fatigue – feeling a bit more tired than usual, especially when you start the medication.
• Minor mood changes – some users notice irritability or a short‑term dip in mood.

These symptoms are usually not dangerous. If they linger past a week or get worse, talk to your pharmacist or doctor.

When to Seek Medical Attention

Serious reactions are rare, but they deserve immediate care. Call your doctor right away if you notice:

• Rash, hives, or swelling of the face, lips, tongue, or throat – signs of an allergic reaction.
• Sudden mood swings, depression, anxiety, or thoughts of self‑harm – Montelukast has been linked to rare neuropsychiatric events.
• Breathing problems that get worse after starting the pill, even if you have asthma under control.
• Unexplained fever, muscle aches, or joint pain that persists.

These warning signs can be serious, so don’t wait.

People with certain health conditions may be more sensitive. Kids under 5, patients with a history of mood disorders, or those taking medications that suppress the immune system should discuss risks with their clinician before starting Montelukast.

Drug interactions can also affect side‑effect chances. Antifungal meds (like ketoconazole), certain antibiotics, or other leukotriene modifiers may raise the level of Montelukast in your blood, increasing side‑effect risk. Always list every prescription, over‑the‑counter drug, and supplement you use.

If a side effect feels manageable, you can often mitigate it with simple tricks: take the pill with food to ease stomach upset, stay hydrated, and avoid alcohol if you feel extra drowsy. Keeping a short journal of symptoms helps you and your doctor spot patterns.

In most cases, the benefits of better breathing outweigh the mild side effects. Still, never ignore a new or worsening symptom – your health is worth the quick check‑in.

Got more questions? Your pharmacist can explain how Montelukast fits into your overall treatment plan, and your doctor can decide if an alternative (like inhaled steroids or a different leukotriene blocker) might be safer for you.

Bottom line: Montelukast works well for many, but stay alert to headaches, stomach upset, and fatigue. If anything feels off – especially rash, mood changes, or breathing trouble – reach out to a healthcare professional right away.