Formoterol, also known as eformoterol, is a long-acting β2 agonist (LABA) used as a bronchodilator in the management of asthma and chronic obstructive pulmonary disease (COPD).

Formoterol has an extended duration of action (up to 12 h) compared to short-acting β2 agonists such as salbutamol (albuterol), which are effective for 4 h to 6 h. Formoterol has a relatively rapid onset of action compared to other LABAs, and is effective within 2-3 minutes.

In November 2005, the US Food and Drug Administration (FDA) released a health advisory alerting the public to findings that show the use of long-acting β2 agonists could lead to a worsening of wheezing symptoms in some patients.

[6] Nowadays, available long-acting β2 agonists include salmeterol, formoterol, bambuterol, and sustained-release oral salbutamol.

Inhaled formoterol works like other β2 agonists, causing bronchodilation by relaxing the smooth muscle in the airway so as to treat the exacerbation of asthma.