Terbutaline (formerly Bricanyl® and Brethine)

Reviewed by: HU Medical Review Board | Last updated: December 2021

Editor's Note: The brands Bricanyl® and Brethine are no longer sold in the United States. Terbutaline is still sold as a generic but is not available as a brand name drug. This drug has a black box warning.

Terbutaline is a bronchodilator, a drug that helps relax the muscles in the airways to make breathing easier. It may be prescribed to treat respiratory conditions related to bronchial asthma, such as wheezing, shortness of breath, and tightness in the chest.1

It is given in tablet or injection form. Terbutaline was used to treat bronchial asthma and bronchospasm that may occur with bronchitis and emphysema.1

What is the active ingredient?

The active ingredient is terbutaline sulfate.

How does it work?

Terbutaline works on the beta-2 adrenergic receptor cells on the smooth muscles in the small tubes inside the lungs. It causes the smooth muscle to relax. By relaxing airway muscles, it helped increase the flow of air through the bronchial tubes of the lungs. This reduces symptoms such as wheezing and shortness of breath.1

Pulmonary function tests usually improve for up to 6 hours after use.1

What are some of the possible side effects?

The most common side effects of terbutaline are:1

  • Nervousness or restlessness
  • Increased potassium levels in the blood
  • Increased blood glucose

Less common symptoms include:

  • Increases in blood pressure, faster heartbeat
  • Headache, dizziness
  • Drowsiness or insomnia
  • Nausea and dry mouth

Things to know

Terbutaline includes a black boxed warning from the US Food and Drug Administration (FDA). This is the strictest warning from the FDA. It has this warning because it should not be used in pregnant women in preterm labor, except in rare cases. It should be used with caution in people with heart disease, diabetes, glaucoma, hyperthyroidism, low potassium (hypokalemia), and seizures.

Terbutaline may also interfere with many types of common prescription drugs, including beta-blockers, drugs used to control diabetes, and certain antidepressants.


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