Asthma Medication Side Effects

Possibilities differ depending on the class, dose, and delivery

As with all drugs, asthma medications are known to have side effects. The range of possibilities is wide, from oral thrush to nervousness to glaucoma. Side effects can vary depending on the drug class, the dose, and how it's delivered (by inhalation or by mouth).

Side Effects of Asthma Medications

Verywell / Laura Porter

Most asthma medications are well tolerated, though, and the benefits of treatment outweigh the consequences. There may be times, however, when a side effect is severe enough that a dose adjustment or different drug entirely is called for.

Inhaled Corticosteroids

Inhaled corticosteroids (commonly known as inhaled steroids) are prescribed to help prevent the symptoms of asthma. When used regularly, they help decrease the frequency and severity of asthma attacks. However, they will not relieve an attack once it has started.

Inhaled corticosteroids can cause both local side effects (limited to a part of the body) and systemic side effects (affecting the entire body). Systemic effects tend to be more severe and are typically associated with long-term use.

Among the possibilities:

The use of a spacer on the mouthpiece of an inhaler may reduce the risk of side effects from inhaled corticosteroids. Rinsing and gargling after use may also prevent hoarseness and oral thrush.

Short- and Long-Acting Beta Agonists

Short-acting beta agonists (SABAs) like albuterol are typically used as rescue medications to provide quick relief of asthma symptoms. By contrast, long-acting beta-agonists (LABAs) like Severant (salmeterol) continue to work for 12 hours or more.

The side effects are much the same for SABAs and LABAs, since the two drug classes share similar mechanisms of action, including:

  • Increased heart rate
  • Headache
  • Dizziness
  • Anxiety
  • Nervousness or tremors
  • Rash

Though the side effects tend to resolve quickly with SABAs, they can often persist with LABAs. The same can occur when either type of beta agonist is used excessively.

While overusing a rescue inhaler can increase your risk of a severe asthma attack, that risk is multiplied if you overuse a LABA. So serious is the concern that the Food and Drug Administration (FDA) was prompted to issue a black box warning in 2003 advising consumers about the risk of fatal asthma attacks when using the combination inhaler Advair (fluticasone/salmeterol).

Oral Corticosteroids

Oral corticosteroids typically are prescribed for people who've experienced or are at risk of a serious asthma attack. While steroids are delivered intravenously in a hospital setting, they are given in oral form if your symptoms are severe but do not require hospitalization.

Side effects are similar to those of inhaled steroids, albeit more common and severe.

Possible side effects, particularly with long-term use of oral corticosteroids, may include:

  • Weight gain
  • Fluid retention
  • High blood pressure
  • Elevated blood sugar
  • Growth suppression in children
  • Osteoporosis (bone density loss) in adults
  • Muscle weakness
  • Cataracts
  • Glaucoma
  • Type 2 diabetes

Fluid retention and elevated blood sugar are also common side effects in those taking oral corticosteroids for a short time.

If you require an oral steroid like prednisone two or more times per year, your asthma is not being well controlled. See your healthcare provider and discuss whether an adjustment of treatment is needed.

Leukotriene Modifiers

Singulair (montelukast) and other leukotriene modifiers work by blocking inflammatory chemicals called leukotrienes, which can trigger bronchoconstriction (narrowing of the airways) leading to an asthma attack.

Common side effects of leukotriene modifiers include:

  • Stomach upset
  • Headache
  • Flu-like symptoms
  • Nervousness
  • Nausea or vomiting
  • Nasal congestion
  • Rash

In most cases, side effects develop within the first month of treatment. Children using leukotriene modifiers may also experience hyperactivity.

Leukotriene modifiers also carry the risk of serious mental health side effects, and in 2020 the the FDA issued a black box warning about these risks. The FDA recommended that healthcare providers carefully weigh the potential risks and benefits before prescribing it for asthma.

Mental health side effects that can occur with leukotriene modifiers include:

  • Agitation
  • Aggression
  • Depression
  • Sleep disturbances
  • Suicidal thoughts
  • Suicide

Contact your healthcare provider immediately if you think you are experiencing a mental health side effect while taking this medication.

Mast Cell Stabilizers

Cromolyn sodium and Alocril (nedocromil) are older therapies used to treat mild persistent asthma. These drugs work by preventing mast cells, a type of white blood cell, from secreting an inflammatory substance called histamine into the bloodstream.

Cromolyn sodium and Alocril are well tolerated, with most side effects decreasing with use. These include:

  • A bad taste in the mouth
  • Cough
  • Itchy or sore throat
  • Headache
  • Nasal congestion
  • Anaphylaxis (rare)

Anaphylaxis is a whole-body, potentially life-threatening allergic reaction. If not treated immediately, people with anaphylaxis may experience shock, coma, asphyxiation, heart or respiratory failure, and even death.

When to Call 911

Call for emergency help if you experience some or all of the following after a mast cell stabilizer or immunomodulator, as these are signs of anaphylaxis:

  • Rash or hives
  • Wheezing
  • Shortness of breath
  • Rapid or irregular heartbeats
  • Dizziness, lightheadedness, or fainting
  • Swelling of the face, tongue, or throat
  • A feeling of impending doom


Xolair (omalizumab) is an immunomodulator delivered by injection. The aim of the treatment is to prevent the immune system from over-responding to an asthma trigger.

Because immunomodulators suppress parts of the immune system, you may be prone to frequent mild-to-moderate infections.

Among other common side effects of immunomodulators are:

  • Swelling and pain at the injection site
  • Itchiness
  • Rash
  • Fatigue
  • Common cold
  • Ear infections
  • Upper respiratory tract infections
  • Sinusitis
  • Acid reflux
  • Headache
  • Sore throat
  • Alopecia (hair loss)
  • Anaphylaxis (rare)

A Word From Verywell

If you do not know how to use your asthma medications correctly or are having problems taking them properly, speak with your healthcare provider. Be honest about what you are experiencing. The same applies if a side effect is persistent or worsening. By working together, you and your practitioner will be able to find the right combination of drugs to control your asthma without significantly impacting your quality of life.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Pat Bass, MD
Dr. Bass is a board-certified internist, pediatrician, and a Fellow of the American Academy of Pediatrics and the American College of Physicians.