Before taking this medication, inform your doctor if you are allergic to mometasone or formoterol; or to arformoterol; or if you have any other allergies in general.
Before using this medication, tell your doctor or pharmacist your medical history. Especially if you have had any of the following; current/past infections (such as tuberculosis, herpes), high blood pressure, heart disease (such as chest pain, heart attack, irregular heartbeat), overactive thyroid (hyperthyroidism), seizures, bone loss (osteoporosis), eye problems (such as cataracts, glaucoma), diabetes, swelling of an artery (aneurysm), a certain tumor of the adrenal gland (pheochromocytoma).
Formoterol may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.
The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using this product, tell your doctor or pharmacist of all the drugs you take and 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 this medication safely.