Formoterol belongs to the class of medications known as bronchodilators. It helps to open airways and make breathing easier. It is used to treat and prevent symptoms of asthma for people 6 years of age and older who are also using inhaled corticosteroids but are still experiencing regular or frequent breakthrough symptoms of asthma (e.g., cough, wheeze, tightened airways). It is also used to prevent asthma symptoms that are caused by exercise.

Do not stop using corticosteroids if you are prescribed formoterol.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

Long-term maintenance therapy:

• Adults: The usual dose of inhaled formoterol is 6 µg or 12 µg twice daily inhaled every 12 hours. Some people may need 24 µg twice daily, as directed by their doctor. The maximum recommended daily dose is 48 µg.
• Children 6 to 16 years old: The usual dose is 6 µg or 12 µg twice daily inhaled every 12 hours. The maximum recommended daily dose is 24 µg.

Prevention of asthma caused by exercise:

• Adults and children (6 years of age and older): The usual dose is 6 µg or 12 µg before exercise.

Formoterol should not be used to treat acute symptoms; it is meant for prevention purposes only.

The effectiveness of the medication depends on the proper use of the device for adequate delivery. Have your doctor or pharmacist instruct you in how to use the device correctly.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important that this medication be used exactly as prescribed by your doctor. If you use this medication regularly and forget a dose, administer it as soon as you remember. If it has been more than 6 hours since your last dose, skip the missed dose and go back to your regular schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

6 µg/metered dose
Each inhalation contains a white-to-off-white or slightly yellow nonhygroscopic crystalline powder of formoterol fumarate dihydrate 6 µg. Nonmedicinal ingredients: lactose monohydrate 1000 µg/metered dose (this amount does not normally cause problems in lactose-intolerant people). Turbuhaler of 60 doses with a light greenish-blue turning grip.

12 µg/metered dose
Each inhalation contains a white-to-off-white or slightly yellow nonhygroscopic crystalline powder of formoterol fumarate dihydrate 12 µg. Nonmedicinal ingredients: lactose monohydrate 1000 µg/metered dose (this amount does not normally cause problems in lactose-intolerant people). Turbuhaler of 60 doses with a dark greenish-blue turning grip.

Do not use formoterol if you:

• are allergic to formoterol or any ingredients of this medication
• are allergic to, or intolerant of, inhaled lactose
• have abnormal heart rhythms associated with fast heart rate
• are not using a corticosteroid inhaler

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• agitation
• dizziness
• headache
• nausea
• nervousness
• palpitations
• restlessness
• trembling or shaking of hands or feet
• trouble sleeping

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• chest pain
• increased blood pressure
• skin rash
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• symptoms of low potassium levels (e.g., muscle weakness, muscle spasms, or an abnormal heart rhythm)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• lumpy skin rash or hives anywhere on the body
• shortness of breath or chest tightness
• signs of a serious allergic reaction (sudden wheezing or difficulty breathing; chest pain or tightness; hives; swelling of the face, lips, or eyes)
• sudden shortness of breath or wheezing after inhalation
• symptoms of a severe asthma attack (e.g., severe increase in shortness of breath, wheezing, cough)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Asthma-related death: Do not stop using corticosteroid medications when you are prescribed formoterol. Formoterol is not a substitute for inhaled corticosteroids. When long-acting bronchodilators, such as formoterol, are used without inhaled (or oral) corticosteroids, there is an increased likelihood of death occurring due to severe asthma symptoms.

Asthma treatment: Do not stop or reduce your dosage of inhaled medications without consulting your doctor, even if you feel better after starting treatment with formoterol. Parents and guardians of children and adolescents who have been prescribed formoterol need to be aware of the importance of consistent and correct use of the medication, the importance of continuing to use the anti-inflammatory medications (corticosteroids) the doctor has prescribed, and the warning signs of worsening asthma such as increased use or reduced effectiveness of formoterol.

Formoterol is intended for the maintenance treatment of asthma only and should not be used in place of a short-acting reliever medication (a "rescue medication") for treatment of acute asthma symptoms. Be sure you have discussed with your doctor and clearly understand what to do in the event of asthma flare-ups. If you find you need to use your short-acting inhaler more often, your condition seems to worsen, or the relief from the formoterol doesn't last as long as it used to, call your doctor. These may be signs that your asthma is worsening, and they need to be evaluated by your doctor.

Bronchospasm: Occasionally, inhaled medications may cause the airways to spasm and close up, making breathing even more difficult (bronchospasm) and can be life-threatening. If you experience increased difficulty breathing after using a dose of formoterol, seek immediate medical attention.

Diabetes: Formoterol can cause increased blood glucose. If you have diabetes or are at risk of developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Drowsiness/reduced alertness: Since in rare cases formoterol may cause dizziness, be cautious when operating dangerous machinery or driving cars until you have determined how formoterol affects you.

Heart rhythm: Rarely, formoterol can cause changes to the normal rhythm of the heart, including an irregular heartbeat called QT prolongation. QT prolongation is a serious life-threatening condition that can cause fainting, seizures, and sudden death. If you are at risk for heart rhythm problems (e.g., people with heart failure, angina, low potassium or magnesium levels), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Monitoring asthma: Talk to your doctor about ways for you to monitor your asthma at home, such as a peak flow meter. Peak flow meters measure the amount of air you can expel in a short time and can help you identify when your asthma might be flaring up even before you begin to experience symptoms.

Thyroid: People with an overactive thyroid gland (hyperthyroidism) are more likely to experience side effects from formoterol. If you have thyroid disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Worsening symptoms: If you find you need to use your short-acting ("rescue") inhaler more often or if your condition seems to worsen, call your doctor. If you have not been given instructions beforehand, contact your doctor immediately about what to do if any of the following situations occur (they may be signs of seriously worsening asthma):

• decreased effectiveness of short-acting, inhaled bronchodilators such as salbutamol, terbutaline, or fenoterol (less than 4 hours of relief)
• need for more inhalations than usual of short-acting, inhaled bronchodilators

Pregnancy: The safety of formoterol during pregnancy has not been established. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if formoterol passes into breast milk. If you are breast-feeding and are using this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of formoterol have not been established for use by children less than 6 years of age. Children and adolescents appear to be more likely to experience asthma symptoms causing hospitalization when they use formoterol.

There may be an interaction between formoterol and any of the following:

• amiodarone
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• antihistamines (e.g., chlorpheniramine, diphenhydramine, dimenhydrinate)
• antipsychotics (e.g., chlorpromazine, haloperidol, ziprasidone)
• atomoxetine
• beta-2 agonists (e.g., indacaterol, olodaterol, salmeterol, vilanterol, terbutaline)
• beta-blockers (e.g., atenolol, carvedilol, propranolol, timolol)
• caffeine
• cannabis
• corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
• decongestants (e.g., naphazoline, oxymetazoline, phenylephrine, pseudoephedrine)
• disopyramide
• diuretics (e.g., furosemide, hydrochlorothiazide)
• dronedarone
• epinephrine
• general anesthetics (medications used to put people to sleep before surgery)
• lenvatinib
• levothyroxine
• linezolid
• MAO inhibitors (e.g., moclobemide, phenelzine, rasagiline, tranylcypromine)
• methadone
• methylphenidate
• modafinil
• nabilone
• norepinephrine
• ozanimod
• procainamide
• propafenone
• quinine
• selpercatinib
• terbutaline
• theophyllines (e.g., aminophylline, theophylline)
• tricyclic antidepressants (e.g., amitriptyline, desipramine, doxepin)
• vandetanib

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.