Along with its needed effects, formoterol may cause some unwanted or undesirable effects. Often, formoterol users who use their medication properly, never experience any unwanted effects. The severity and duration of these effects are dependant on many factors including duration of therapy, dose, route of administration and individual response. Common:

• headache
• tremor
• dizziness
• dry mouth
• slight palpitations (awareness of heart beat)

Uncommon:

• muscle cramps and pain
• feeling nervous or tired
• agitation
• difficulties in sleeping

Rare:

• allergic reaction (rash, swelling of face and throat)
• cardiac arrythmias (e.g., atrial fibrillation, supraventricular tachycardia, estrasystoles)
• hypokalemia
• worsening of asthma symptoms

Check with your pharmacist or doctor if mild effects persist and become bothersome or if more severe effects occur.

Formoterol is a long-acting bronchodilator that acts at specific receptors called beta2-adrenergic receptors. Stimulating these receptors makes breathing easier by opening the small air passages in the lungs. Formoterol starts to improve breathing within 1 to 3 minutes. This fast onset of action is similar to that seen with short-acting bronchodilators. The bronchodilating effect of formoterol typically lasts for 12 hours. This duration is similar to that seen with other long-acting beta2-agonists.

 Long-acting beta2-adrenergic agonists (LABA), such as formoterol may increase the risk of asthma-related death. This increased risk was determined based on the evidence from a large study done in the United States with another LABA called salmeterol. Because of this risk, LABAs like formoterol must never be used alone to treat asthma. They should be used as add-on therapy for patients with asthma who continue to have poor asthma control despite an optimal dose of inhaled corticosteroids (ICS). In asthma, formoterol must be used together with an appropriate dose of inhaled corticosteroid .

• Maximum benefit cannot be achieved unless the inhalation device is used correctly. Even if you have used this device before, you should have your technique reassessed by your pharmacist and read the patient instructions that are provided with each inhaler.
• Formoterol should be used as an additional therapy to low-to-medium dose inhaled corticosteroids. Do not use Formoterol as monotherapy in asthma patients or as a substitute for oral or inhaled corticosteroids. Corticosteroids should not be stopped when Formoterol is initiated.
• Formoterol can be used to treat acute symptoms (Oxeze® only; NOT Foradil®), however, medical attention should be sought if patients find that relief bronchodilator treatment becomes less effective or that they need more inhalations than usual.

Do not use formoterol:

• If you are allergic to it or to other bronchodilators such as salbutamol

Caution is advised in:

• heart disease
• high blood pressure
• overactive thyroid
• history of seizures
• pheochromocytoma
• low blood levels of potassium or magnesium

Drug interactions: Make sure your doctor and pharmacist know that you are on the following:

• diuretics or water pills
• any medications that affect heart rhythm such as: amiodarone, quinidine, sotalol
• some antibiotics, such as: erythromycin, clarithromycin

Use in pregnancy: Human data is limited.  If you suspect that you might be pregnant, consult your doctor. 

Use in breastfeeding: Human data is limited.  It is unlikely that the amount in breast milk would present problems to the infant, but always check with doctor or pharmacist before use.