Formoterol

What it is

Formoterol is a long-acting beta-2 agonist that relaxes airway smooth muscle, with an onset that is fast but an effect that lasts many hours. It is used in asthma and COPD to keep the airways open through the day and night. In asthma it is a maintenance treatment, not a substitute for a reliever used alone.

Used for

• Asthma
• COPD

What to know while taking it

In asthma it is prescribed only in combination with an inhaled steroid, because a long-acting bronchodilator used without one leaves the underlying airway inflammation untreated and worsens outcomes; combination inhalers exist so the two cannot be separated by accident. In COPD it is also used without one. A faster heart rate, palpitations and tremor can occur, and beta-blockers such as bisoprolol and metoprolol work against it and may reduce its effect. Like other beta-2 agonists it can lower blood potassium, so potassium is the marker to keep an eye on.

When to see a doctor

Breathlessness or wheeze that is getting worse despite regular use, or a need for reliever inhaler that keeps climbing, means see a doctor. Sustained palpitations, an irregular heartbeat, or marked weakness and cramping also warrant review.

Worth knowing

• Only together with an inhaled steroid
• Can raise the heart rate

Markers to watch

• Potassium