If severe symptoms of asthma do not respond to other medications, a doctor may administer magnesium sulfate to relax bronchial muscles and expand airways.

Asthma is a common condition. According to the Centers for Disease Control and Prevention (CDC) in the United States, asthma affects around 20.4 million adults and 6.1 million children in the country.

Asthma causes inflammation in the airways, or bronchial tubes, which move air in and out of the lungs. The inflammation triggers the body to produce excess mucus. The presence of mucus can restrict the flow of air and affect a person’s breathing.

Symptoms of asthma can include coughing, wheezing, chest tightness, and shortness of breath. They may come and go, and the severity of asthma can vary considerably from person to person.

When symptoms suddenly get worse, doctors call this an asthma attack, a flare-up, or an exacerbation of symptoms.

Many medications can treat or prevent symptoms of asthma. For a severe or life-threatening flare-up, a doctor may use magnesium sulfate.

In this article, we discuss asthma treatments and when magnesium sulfate can help. We also describe the side effects.

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People can inhale magnesium sulfate using a nebulizer.

There is currently no cure for asthma. Treatment aims to relieve symptoms and prevent flare-ups.

Many people with asthma must take medications regularly. It is often necessary to identify and avoid factors that trigger symptoms.

Doctors work closely with people with asthma to tailor a treatment plan. This may involve a combination of quick-relief medications for flare-ups and long-term medications to prevent symptoms from returning.

A person usually uses an inhaler to absorb these drugs, but some come in tablet form.

Asthma medications can include:

  • bronchodilators, which open up the airways
  • corticosteroids, which reduce inflammation and mucus production within the airways
  • anticholinergics, which reduce muscles tightness around the airways
  • antibiotics, which help treat lung infections that can trigger symptoms

For severe or life-threatening flare-ups that do not respond to other treatments, a doctor may administer magnesium sulfate.

Magnesium sulfate is a bronchodilator. It relaxes the bronchial muscles and expands the airways, allowing more air to flow in and out of the lungs. This can relieve symptoms of asthma, such as shortness of breath.

Doctors mainly use magnesium sulfate to treat people who are having severe asthma flare-ups.

They usually administer the medication through an intravenous (IV) injection or infusion. In some cases, a person can inhale the drug using a nebulizer.

Magnesium sulfate is not a first-line treatment for asthma flare-ups. Doctors typically only administer the drug in the emergency department, when other treatments have not succeeded.

The scientific evidence supporting the use of magnesium sulfate in the treatment of severe asthma is mixed.

Authors of a 2013 study recruited 508 children from British hospitals who had severe flare-ups of asthma that had not responded to standard inhaled treatment.

The researchers randomly assigned the children to receive either nebulized magnesium sulfate or a placebo, in addition to standard asthma medications.

They concluded that nebulized magnesium sulfate in combination with standard treatment did not produce a clinically significant improvement in the children’s asthma symptoms.

However, the authors noted that children with more severe asthma symptoms showed the most significant response to magnesium treatment.

In 2014, another large British trial set out to establish how effectively magnesium sulfate could reduce asthma symptoms.

The authors recruited 1,109 adults with severe acute asthma and randomly assigned participants to receive either IV magnesium, nebulized magnesium, or standard therapy alone.

The researchers were reportedly unable to demonstrate a “clinically worthwhile benefit” of magnesium sulfate treatment. However, they found some “weak evidence” that IV magnesium sulfate could reduce the number of hospitalizations due to asthma attacks.

The findings of a systematic review, published in the same year, were more positive. The researchers analyzed data from 14 trials that had compared IV magnesium sulfate treatment to placebos in adults with acute asthma.

The authors determined that IV magnesium sulfate treatment reduced the number of hospital admissions and improved lung function in people with acute asthma that had not responded to standard treatments.

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Nausea may be a side effect of magnesium sulfate.

Possible side effects of magnesium sulfate can include:

  • skin flushing
  • nausea
  • vomiting
  • muscle weakness
  • respiratory problems
  • low blood pressure
  • confusion
  • an irregular heartbeat
  • coma

Magnesium sulfate can also interact with some medications. It is essential for people to inform healthcare professionals of all the medications that they are currently taking.

A range of medications, including inhaled bronchodilators and corticosteroids, can treat and prevent symptoms of asthma.

If a severe flare-up of symptoms has not responded to other treatments, a doctor may use IV magnesium sulfate. They typically administer this drug in the emergency department.

Scientific evidence for the effectiveness of magnesium sulfate is inconsistent, but it may help to reduce the likelihood that a person experiencing a severe asthma attack will need to be admitted to the hospital.