Allergies occur when the immune system treats a harmless
foreign protein as an invader. The immune system mounts a full-scale response
to the protein. This response involves releasing inflammatory chemicals. These
chemicals recruit the involvement of other cells and promote more inflammation.
What Are Leukotrienes?
Leukotrienes are fatty immune system chemicals that come from
dietary omega-3 and omega-6 fatty acids. They play a key role in some of the
more severe symptoms of allergic rhinitis and allergy-induced asthma.
The symptoms of allergic rhinitis may include:
- swelling of the nasal passages
- increased mucus production
- a stuffy or runny nose
- itchy skin
In people with asthma, leukotrienes bind with receptors on
muscle cells. This causes the smooth muscles of the windpipe to contract. When
airways are constricted, people with asthma experience shortness of breath and
How Do Leukotriene Modifiers Work?
Drugs that modify the production or activity of leukotriene
are known as leukotriene inhibitors, leukotriene receptor antagonists, or
leukotriene modifiers. Some of these drugs work by limiting the production of
leukotrienes. Others block leukotrienes from binding to their receptors on
smooth muscle cells. If the fatty signaling molecules cannot bind with their
cellular targets, they cannot trigger muscle contraction.
Drugs such as montelukast
(Singulair) and zafirlukast
(Accolate) are widely prescribed to treat exercise and allergy-induced asthma.
A third drug called zileuton
(Zyflo) indirectly inhibits leukotriene synthesis. Montelukast is also
prescribed for the treatment of year-round and seasonal allergic rhinitis.
These drugs are usually taken by mouth.
When Would Your Doctor Prescribe Leukotriene Modifiers?
Inhaled corticosteroids are the most effective treatment.
These drugs offer comprehensive relief from the various symptoms of allergic
rhinitis, so they’re considered first-line treatment. However, in cases where people
experience both allergy-induced asthma and allergic rhinitis, leukotriene
modifiers may be considered first-line treatment.
Leukotriene modifiers are one of several types of drugs used
to treat allergies or asthma. However, they’re still considered second-line
treatment. They were introduced in the 1990s. They were the first new class of
drugs for the treatment of asthma and allergies in 30 years. Some studies have shown that
leukotriene modifiers provide an effective singular, first-line therapy for the
control of mild asthma in children.
Side Effects of Leukotriene Modifiers
Although they’re widely prescribed and considered relatively
safe, leukotriene modifiers cause side effects in some people. Possible side
effects listed for the drug montelukast, for instance, include changes in mood
and increased suicidal thoughts.
The U.S. Food and Drug Administration (FDA) initiated an
inquiry into these and other neuropsychiatric effects in 2008. In 2009,
they concluded that existing clinical trials reveal an increased risk of
developing insomnia among users of this class of drugs, compared to a placebo.
According to the FDA, information gathered from people after
the public release of these drugs indicates an increased risk of:
- dream abnormalities
- suicidal thinking and behavior
The FDA concluded its review by noting, “neuropsychiatric
events were not commonly observed,” at least not in clinical trials, although
the FDA also noted that these trials weren’t specifically designed to detect
Leukotriene modifiers can help people manage severe asthma
and the symptoms of allergies. You should make sure you understand all of the
possible side effects before you start a new medication. You should always let
your doctor know if you’re concerned about any symptoms you’ve developed after
starting a new medication.