If you’ve been experiencing ongoing asthma or allergy symptoms, there’s a chance your doctor has mentioned leukotriene inhibitors as a potential treatment option.

Leukotrienes are chemical mediators released by the immune system. They are released in response to triggers. In people with overactive mast cells or underlying health conditions, leukotrienes can be released in higher amounts or at inappropriate times, contributing to ongoing allergy and asthma symptoms.

Leukotriene inhibitors are one treatment option that can help reduce inflammation and the risk of flare-ups.

In this article, we get into what you need to know about leukotriene inhibitors, from the most-prescribed medications, how they work, and important considerations you should know before you begin.

Let’s dive in.

What are leukotriene inhibitors?

Leukotriene inhibitors are also known as leukotriene modifiers or leukotriene receptor antagonists (LTRAs). They block the effects of leukotrienes or reduce their production.

Leukotrienes are chemical mediators released by immune cells like mast cells. They are released when these cells are triggered by things like pollen, dust mites, pet dander, respiratory infections, or physical exercise.

When they bind to their receptors, leukotrienes cause symptoms, including mucus production, narrowing of the airways, swelling, and congestion.

Leukotriene inhibitors are most commonly prescribed to treat:

• Hay fever (allergic rhinitis)
• Asthma (allergy-induced and exercise-induced)

People with mast cell conditions like mast cell activation syndrome (MCAS) and mastocytosis may also be prescribed leukotriene inhibitors. In these conditions, mast cells release multiple chemical mediators, including leukotrienes, which contribute to symptoms like wheezing and abdominal cramping.

Leukotriene inhibitors target this pathway, which means they may help reduce these symptoms in some people.

How leukotriene inhibitors work

Leukotriene inhibitors prevent leukotrienes from binding to receptors and causing symptoms. They can also reduce leukotriene production.

Most people only experience leukotriene-related symptoms in flare-ups. In these cases, leukotriene inhibitors offer relief. However, some people have overactive immune systems or other chronic health conditions that impact their immune function. This can cause long-lasting severe allergy and asthma symptoms that can impact their quality of life.

Taking leukotriene inhibitors is one management option, as they reduce the effects of leukotrienes in the body.

Types of leukotriene inhibitors

There are two types of leukotriene inhibitors, and they work differently:

• Leukotriene receptor antagonists block the receptors on the surface of cells, preventing leukotrienes from binding and causing symptoms.

• Leukotriene synthesis inhibitors block enzymes used to create leukotrienes, so the body doesn’t produce them in the first place.

{{pro-tip-1}}

Here are a few of the most commonly prescribed leukotriene inhibitors for asthma and allergies:

Montelukast

Montelukast (Singulair®) is primarily prescribed to manage asthma symptoms, including wheezing, difficulty breathing, chest tightness, and cough.

It is a leukotriene receptor antagonist, so it works by blocking leukotrienes from binding with receptors and causing inflammation. 

Montelukast is taken daily orally (tablet or drinkable granules) to prevent symptoms.

Possible side effects include:

• Headaches
• Heartburn
• Stomach pain
• Fatigue
• Diarrhea

Contact your doctor immediately if you notice any of these serious side effects:

• Difficulty breathing or swallowing
• Swelling of the face, tongue, throat, lips, or eyes
• Hoarse voice
• Itchy skin
• Hives
• Rash
• Flu-like symptoms
• Pins-and-needles, numbness, or tingling in your arms or legs

Montelukast can cause serious mental health side effects, which may occur during treatment or after stopping the medication. These can include changes in mood, behavior, or thinking, such as anxiety, irritability, sleep disturbances, memory problems, hallucinations, or suicidal thoughts.

Tracking changes in your baseline mental health while taking montelukast can help you identify potential side effects early.

Zafirlukast

Zafirlukast (Accolate®) is another leukotriene receptor antagonist prescribed to prevent asthma symptoms. It’s taken orally as a tablet.

Headache is a common possible side effect of zafirlukast.

Contact your doctor immediately if you notice any of these serious symptoms:

• Nausea
• Loss of appetite
• Pain in the upper-right area of the stomach
• Fatigue
• Itchiness
• Flu-like symptoms
• Rash
• Hoarse voice
• Swelling of the facial area
• Numbness, pain, burning, or tingling in the hands or feet 
• Yellowing of the skin or eyes (jaundice)

Zafirlukast can cause mental health changes, including anxiety, irritability, sleep disturbances, unusual dreams, hallucinations, depression, restlessness, or suicidal thoughts or behavior.

If you notice any of these symptoms, contact your doctor as soon as possible. They will advise whether you should continue taking zafirlukast.

Zileuton

Zileuton (Zyflo®) is a leukotriene synthesis inhibitor primarily used to manage asthma symptoms, including wheezing, shortness of breath, and coughing. It works by blocking the enzymes needed to create leukotrienes in the body.

It’s taken as a tablet, and there’s also an extended-release option.

Possible side effects of zileuton include:

• Headache
• Heartburn
• Diarrhea
• Muscle pain
• Nose and throat irritation
• Facial pain or fullness

Some side effects may be more serious. Contact your doctor if you experience:

• Rash
• Hives
• Vomiting
• Fatigue
• Itching

Zileuton can affect liver function, so monitoring is usually required while taking this medication. It may not be prescribed to you if you have liver disease.

Contact your doctor right away if you experience symptoms that could suggest liver problems, such as:

• Dark urine
• Pain in the upper abdomen
• Loss of appetite
• Unusual fatigue
• Yellowing of the skin or eyes (jaundice)
• Flu-like symptoms

Taking leukotriene inhibitors safely

Leukotriene inhibitors are not a safe choice for everyone. Before taking the medication, be sure to tell your doctor if:

• You are taking other medications, as there may be contraindications
• You have liver disease
• You have a mental health condition
• You are breastfeeding, pregnant, or plan to become pregnant

It is possible to take too much leukotriene inhibitor medication and experience overdose symptoms. To avoid overdose, only take the dose you are prescribed. Never take two doses at once if you miss one.

Signs of overdose range in severity from nausea and headache to difficulty breathing and seizure. If you or a loved one takes too much medication, call 911 immediately. 

Always store leukotriene inhibitors in a dry, room-temperature place out of the reach of children. Avoid moisture and direct sunlight.

{{inline-cta-1}}

Frequently asked questions

What do leukotrienes do?

Leukotrienes are inflammatory mediators made by white blood cells. They bind with leukotriene receptors, sometimes causing unwanted effects, including asthma symptoms or allergy-like symptoms.

They also cause symptoms in some people with mast cell conditions like MCAS.

Is Claritin a leukotriene inhibitor?

No, Claritin is not a leukotriene inhibitor.

Claritin (loratadine) is a second-generation antihistamine that blocks histamine from causing unwanted effects in the body.

Both histamine and leukotrienes act as mediators in the inflammation cascade, which is why taking Claritin may result in a similar effect as taking a leukotriene inhibitor.

How can you block leukotrienes naturally?

There is only limited evidence showing that diet or supplements can meaningfully reduce leukotriene activity in the body.

For this reason, approaches like dietary changes or supplements should not be relied on as a substitute for prescribed treatments such as leukotriene inhibitors.

If you are considering supplements or significant dietary changes, speak to your doctor first to make sure they are safe for you.

Disclaimer: Human Health is a health tracking platform and does not provide medical advice, diagnosis, or treatment. The information on this site is intended to support, not replace, conversations with qualified healthcare professionals.

Sources:

1. Leukotriene modifiers, Cleveland Clinic
2. Physiology, Leukotrienes (2023)
3. Leukotriene receptor antagonists (2023)
4. Montelukast, MedlinePlus
5. Zafirlukast, MedlinePlus‍
6. Zileuton, MedlinePlus