SIDE EFFECTS: Shakiness (tremor), nausea, headache, nervousness, dizziness, dry mouth, or trouble sleeping may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur: muscle weakness/cramps, increased thirst/urination.

Seek immediate medical attention if any of these rare but very serious side effects occur: chest pain, severe dizziness, fainting, fast/irregular heartbeat.

Rarely, this medication has caused severe (possibly fatal), sudden worsening of breathing problems (paradoxical bronchospasm). If you have trouble breathing or experience sudden wheezing, use your quick-relief inhaler and seek immediate medical attention.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the Perforomist (formoterol fumarate inhalation solution) Side Effects Center for a complete guide to possible side effects »

PRECAUTIONS: Before using formoterol, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: diabetes, heart problems (e.g., irregular heartbeat, angina), high blood pressure, liver problems, overactive thyroid (hyperthyroidism), seizures.

Formoterol may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can infrequently result in serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that require immediate medical attention. The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may affect the heart rhythm (see also Drug Interactions section). Before using formoterol, tell your doctor or pharmacist if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using formoterol safely.

Before having surgery, tell your doctor or dentist that you are using this medication.

This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is not known if this drug passes into breast milk. Consult your doctor before breast-feeding.