Before using this medication, tell your doctor or pharmacist if you are allergic to mometasone or formoterol; or to arformoterol; 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: 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 adrenal gland tumor (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.

This medication may mask signs of infection. It can make you more likely to get infections or may make current infections worse. Stay away from anyone who has an infection that may easily spread (such as chickenpox, COVID-19, measles, flu). Talk to your doctor if you have been exposed to an infection or for more details.

If you have switched from a corticosteroid taken by mouth (such as prednisone tablets) to this inhaler within the past 12 months, or if you have been using this product in higher-than-usual doses for a long time, it may be more difficult for your body to respond to physical stress. Before having surgery or emergency treatment, or if you get a serious illness/injury, tell your doctor or dentist that you are using this medication or have used a corticosteroid taken by mouth within the past 12 months. Tell your doctor right away if you develop unusual/extreme tiredness or weight loss. Carry a warning card or medical ID bracelet that says you use (or have used) corticosteroid medications.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This medication may temporarily slow down a child's growth if used for a long time. However, poorly controlled asthma can also slow down growth. See the doctor regularly so your child's height can be checked.

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).

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

It is unknown if this medication passes into breast milk. Consult your doctor before breastfeeding.