What to Know About Asmanex (Mometasone)

An inhaled corticosteroid for the prevention of asthma attacks

Asmanex (mometasone) is an inhaled medication used daily for the long-term control of asthma symptoms. It belongs to a class of drugs called corticosteroids that reduce airway inflammation. By controlling inflammation, you will be less sensitive to asthma triggers and less likely to have an asthma attack.

Asmanex is available as either an aerosolized metered-dose inhaler (MDI) or a non-aerosolized dry powder inhaler (DPI). It is one of several inhaled corticosteroids your doctor will consider if you are unable to control your asthma with a rescue inhaler alone.

There are no generic versions of Asmanex in the United States.

The correct technique for using the Asmanex Twisthaler.
Daniel More, MD


Asmanex in an inhaled corticosteroid (a.k.a. steroid) that alleviates inflammation in the airways⁠. Because of their limited exposure, inhaled steroids are less likely to than oral corticosteroids that treat inflammation systemically (throughout the entire body).

Asmanex is not used to treat acute asthma symptoms but rather to temper airway inflammation and hyperresponsiveness so that that attacks don't occur in the first place.

There are two versions of Asmanex approved by the U.S. Food and Drug Administration (FDA):

  • Asmanex HFA is approved for the treatment of asthma in adults and children 12 years of age and over.
  • Asmanex Twisthaler is approved for the treatment of asthma in adults and children 4 and over.

Asmanex may be used on its own as a daily controller medication. If needed, an inhaled long-acting beta-agonist (LABA) may be added to the treatment plan if Asmanex is unable to provide sustained control of symptoms.

In fact, an increasing number of experts, including the Global Initiative for Asthma (GINA), endorse the combined use of an inhaled steroid and LABA rather than a stepped approach to treatment.

Neither Asmanex HFA nor Asmanex Twisthaler is inherently "better" than the other. There are pros and cons to each device that you need to discuss with your doctor to make an informed choice.

Asmanex HFA
  • Requires hand-breath coordination

  • Spacers can be used to reduce the risk of oral thrush

  • Needs to be primed to prevent clogging

  • Cannot be used in younger children

  • Requires twice-daily dosing

  • Generally fewer side effects

Asthmanex Twisthaler
  • Does not require hand-breath coordination; you simply inhale

  • Cannot accommodate a spacer

  • Does not need to be primed

  • Can be used in children as young as four

  • Requires once-daily dosing in most cases

  • Generally more side effects

Asmanex is one of several FDA-approved inhaled corticosteroids used in the treatment of asthma. Others options include:

Off-Label Uses

Asmanex is not approved for the treatment of chronic obstructive pulmonary disease (COPD) but is used off-label by some pulmonologists to help sustain control of COPD exacerbations.

An application was submitted to the FDA requesting approval of the combination drug Dulera—which pairs Asmanex's active ingredient (mometasone) with a LABA (formoterol)—for the treatment of severe COPD. Research is ongoing.

Other studies are investigating the combined use of mometasone with another LABA called indacaterol in the treatment of COPD.

Before Taking

Inhaled steroids like Asmanex are commonly added to the treatment plan if you are unable to control your asthma with a short-acting beta-agonist (SABA), also known as a rescue inhaler.

According to the American Lung Association, your asthma is being poorly controlled if you experience any of the following:

  • You have asthma symptoms two or more days per week.
  • Your asthma awakens you at night more than twice a month.
  • You use your rescue inhaler more than twice weekly.
  • Normal everyday activities are being impaired by asthma.
  • Your lung function, as measured by your peak flow or forced expiratory volume in one second (FEV1), has worsened despite treatment.

While the frequency of attacks or SABA use may be enough to motivate for treatment, your doctor will still want to measure your lung function using in-office spirometry and other pulmonary function tests (PFTs).

These tests can help characterize the disease more accurately and determine if you have mild, moderate, or severe asthma. These classifications are used to direct treatment decisions and ensure that you are neither being undertreated nor overtreated.

Precautions and Considerations

The only absolute contraindication to Asmanex use is a known allergy to mometasone or any of the other ingredients in the inhaler. People with a severe milk allergy should avoid Asthamex Twisthaler as it contains milk powder.

Because inhaled steroids suppress the immune system, they can reduce the body's ability to fight certain bacterial, viral, fungal, or parasitic infections. This includes pneumonia, candidiasis (thrush), tuberculosis, and herpes simplex. It is best to treat and clear any active infection before starting Asmanex.

Asmanex can also increase a child's vulnerability to common childhood infections like chickenpox and measles. Because the drug suppresses the immune system, children who get these infections will often get them worse than others. To avoid this, be sure to have your child vaccinated for chickenpox and measles prior to starting Asmanex.

Asmanex can decrease bone mass density and inhibit growth in younger children. The drug should be used with caution in people with pre-existing osteopenia or osteoporosis. Children using Asmanex should be regularly monitored for impaired growth, although the loss in height or bone size is generally minimal).

Asmanex can cause changes in vision with long-term use. The drug should be used with extreme caution in people with glaucoma or cataracts. Vision tests should be regularly performed to check for changes in vision.

Asmanex should also be used with caution people with pre-existing adrenal insufficiency (Addison's disease) because the drug can further suppress the production of the hormone cortisol and trigger an adrenal crisis.


The recommended dosage of Asmanex varies by formulation, age, and whether you have been exposed to corticosteroids in the past.

Asmanex HFA

Asmanex HFA is prescribed as a twice-daily dose in adults and children over 12. It is available in a 100-microgram (mcg) and 200 (mcg) formulation, the choice of which is determined by your prior corticosteroid use.

Recommended Dosage Asmanex HFA
Prior Corticosteroid Use Recommended Dose
None 100 mcg, two inhalations twice daily
Inhaled medium-dose corticosteroids 100 mcg, two inhalations twice daily
Inhaled high-dose corticosteroids 200 mcg, two inhalations twice daily
Oral corticosteroids 200 mcg, two inhalations twice daily

Asmanex Twisthaler

Asmanex Twisthaler can be used in children as young as 4. Depending on one's age and prior treatments, the drug may be needed once or twice daily.

Asmanex is available in a 110-mcg and 220-mcg formulation. As a rule, the lowest effective dose should always be used to minimize the risk of side effects. If the dose is unable to control your symptoms, it can be increased under the direction of a doctor.

Never increase or decrease your Asmanex dose without first speaking with your doctor.

Recommended Dosage Asmanex Twisthaler
Age and/or Previous Therapy Recommended Starting Dose Maximum Daily Dose
Adults and children over 12 who only used a rescue inhaler 220 mcg once daily in the evening 440 mcg
Adults and children over 12 who used inhaled corticosteroids 220 mcg once daily in the evening 440 mcg
Adults and children over 12 who used oral corticosteroids 440 mcg once in the evening 880 mcg
Children 4 to 11 110 mcg once daily in the evening  110 mcg

How to Take and Store

It can take up to two weeks before you feel the full effects of Asmanex HFA or Asnamex Twisthaler. To achieve the optimal response, you need to take Asmanex every day in evenly spaced doses.

Once-daily doses should be taken at the same time every evening. Twice-daily doses should be taken 12 hours apart, once in the morning and once in the evening.

If you miss a dose of Asmanex, take it as soon as you remember. If it is near the time of your next dose, skip the missed dose and continue as normal. Never double up.

Asmanex HFA and Asmanex Twisthaler can be both stored at room temperature, ideally between 66 degrees F and 77 degrees F. If traveling, it is OK to store your inhaler at temperatures of up to 86 degrees F for a short period of time. Never incinerate or puncture Asmanex HFA as this can cause an explosion.

Whichever inhaler you ultimately use, it is important to use it correctly so that you get the right amount of mometasone into the airways.

Using Asmanex HFA

  1. If using the inhaler for the first time (or if you have not used it in more than five days), prime the device by spraying it into the air four times. If you have used the inhaler within five days, priming is not necessary.
  2. Shake the inhaler vigorously for five seconds.
  3. Take the cap off and add a spacer to the mouthpiece if you use one.
  4. Exhale fully and place the mouthpiece in your mouth, wrapping your lips to form a tight seal.
  5. Breathe in deeply through your mouth as you simultaneously depress the inhaler.
  6. Hold your breath for about 10 seconds, then exhale slowly.
  7. Wait 30 seconds, shake the canister, and repeat steps 4 to 6.
  8. Once completed, rinse your mouth with water. Do not swallow.
  9. Replace the cap.

The mouthpiece and spacer should be cleaned once weekly using a dry wipe. Do not submerge the inhaler in water.

Asmanex HFA as equipped with a built-in dose counter; there are 120 doses per inhaler. With every puff you take, the counter will indicate how many doses are left. When the dose counter reads "020," it is time to order a refill.

Using Asmanex Twisthaler

  1. Twist off the cap of the inhaler canister in a counter-clockwise direction.
  2. When the cap is removed, a single dose is automatically loaded.
  3. Exhale to completely empty the lungs.
  4. Place the mouthpiece into your mouth, making a tight seal with your lips.
  5. Inhale with a single long, deep breath.
  6. Remove the mouthpiece and hold your breath for 10 seconds.
  7. Exhale slowly.
  8. To load the next dose, screw the cap back on in a clockwise direction. Then, twist it off once again in a counter-clockwise direction.
  9. Repeat steps 3 through 7.
  10. Rinse your mouth thoroughly with water. Do not swallow.
  11. Replace the cap.

Asmanex Twisthaler does not need to be cleaned regularly, but you may want to wipe the mouthpiece with a tissue or dry cloth after each use.

There are 30 inhalations in each 110-mcg Twisthaler and 120 inhalations in each 220-mcg Twisthaler. You will need to refill your prescription when the dose counter reads "10" for the 110-mcg Twisthaler and "020" for the 220-mcg Twisthaler.

Side Effects

As with all drugs, Asmanex may cause side effects. Many of the side effects are mild and will resolve as your body adapts to treatment. Call your doctor if any side effect persists or worsens.

There tend to be more side effects with Asmanex Twisthaler than with Asmanex HFA. This may inform the choice of drug you finally decide to use.


Among the common side effects of Asmanex HFA and Asmanex Twisthaler affecting at least 3% of user are (in order of frequency):

Asmanex HFA
  • Common cold

  • Headache

  • Flu

  • Sinus infection

Asmanex Twisthaler
  • Headache

  • Hay fever

  • Sore throat

  • Upper respiratory infections

  • Sinus infection

  • Oral thrush

  • Irregular periods

  • Muscle ache

  • Back ache

  • Upset stomach

  • Stomach pain

  • Nausea

Asmanex HFA can also cause oral thrush in less than 1% of cases. A spacer can help reduce the risk as can rinsing your mouth thoroughly after each treatment.


The long-term use of any corticosteroid can lead to side effects, some of which may be severe or irreversible. These include eye problems, bone loss, and adrenal insufficiency. Call your doctor if you develop any of the following while on Asmanex:

On rare occasions, Asmanex can also cause a potentially life-threatening, whole-body allergy known as anaphylaxis. If not treated immediately, anaphylaxis can lead to shock, coma, heart or respiratory failure, and death.

Anaphylaxis is always considered a medical emergency.

When to Call 911

Seek emergency care if you experience any of the following signs and symptoms of anaphylaxis after using Asmanex:

  • Hives or rash
  • Shortness of breath
  • Wheezing
  • Rapid or irregular heartbeats
  • Dizziness or lightheadedness
  • Confusion
  • Swelling of the face, tongue, or throat
  • A sense of impending doom

Warning and Interactions

Never stop Asmanex without first speaking with your doctor. Doing so can trigger withdrawal symptoms and potentially trigger an asthma attack. This is especially true if you take high doses daily.

To avoid withdrawal, your doctor may need to reduce the dose gradually over the course of several weeks.

One case in which use of Asmanex HFA or Asmanex Twisthaler needs to cease temporarily is oral thrush. Continuing treatment can make the condition worse.

If you experience any infection while on Asmanex therapy, including respiratory infections such as flu or pneumonia, call your doctor immediately. You may need to stop treatment temporarily until the infection is appropriately treated and cleared.

Drug Interactions

Asmanex HFA and Asmanex Twisthaler utilize a liver enzyme called cytochrome P450 (CYP450) for metabolization. Because a wide variety of other drugs also rely on CYP450 for metabolization, there is a risk of interaction as the drugs "compete" for the available enzyme.

This can lead to increases or decreases in the concentration of one or both drugs. Increased drug concentrations can lead to more and/or more severe side effects, while low concentrations can reduce the effectiveness of a drug.

Among the interactions of concern are:

Some interactions may require a dose adjustment or the separation of doses by one or more hours. Others may require a drug substitution or no action at all.

To avoid interactions, let your doctor know about any and all drugs you are taking whether the prescription, over-the-counter, herbal, or recreational.

A Word From Verywell

Asmanex can be an effective tool in the long-term treatment of asthma, but only if you use it as prescribed. Current research suggests that at least 30% of people with asthma fail to adhere to daily inhaled steroids, translating to a 34% increase in asthma-related hospitalization.

If you have problems adhering to treatment, let your doctor know. In some cases, the doctor may be able to prescribe combination inhalers that ease the daily rigor of medication-taking or find drugs with fewer side effects and greater tolerability.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Merck & Co. Asmanex HFA 100 mcg (mometasone furoate) inhalation aerosol Asmanex HFA 200 mcg (mometasone furoate) inhalation aerosol for oral use. Updated April 2014. 

  2. Merck & Co. Asmanex Twisthaler 110 mcg, 220 mcg (mometasone furoate inhalation powder). Updated January 2008.

  3. Global Initiative for Asthma. Global strategy for asthma management and prevention. Updated 2019.

  4. Doherty DE, Tashkin DP, Kerwin E, et al. Effects of mometasone furoate/formoterol fumarate fixed-dose combination formulation on chronic obstructive pulmonary disease (COPD): results from a 52-week phase III trial in subjects with moderate-to-very severe COPD. Int J Chron Obstruct Pulmon Dis. 2012;7:57-71. doi:10.2147/COPD.S27320

  5. Tashkin DP, Doherty DE, Kerwin E, et al. Efficacy and safety of a fixed-dose combination of mometasone furoate and formoterol fumarate in subjects with moderate to very severe COPD: results from a 52-week Phase III trial. Int J Chron Obstruct Pulmon Dis. 2012;7:43-55. doi:10.2147/COPD.S27319

  6. Barjaktarevic IZ, Arredondo AF, Cooper CB. Positioning new pharmacotherapies for COPD. Int J Chron Obstruct Pulmon Dis. 2015;10:1427-42. doi:10.2147/COPD.S83758

  7. American Lung Association. Assess and monitor your asthma control. Updated February 28, 2019.

  8. Rostaing L, Malvezzi P. Steroid-based therapy and risk of infectious complications. PLoS Med. 2016;13(5):e1002025. doi:10.1371/journal.pmed.1002025

  9. Liyanage CK, Galappatthy P, Seneviratne SL. Corticosteroids in management of anaphylaxis; a systematic review of evidence. Eur Ann Allergy Clin Immunol. 2017;49(5):196-207. doi:10.23822/EurAnnACI.1764-1489.15

  10. Rogers L, Reibman J. Stepping down asthma treatment: How and when. Curr Opin Pulm Med. 2012;18(1):70-5. doi:10.1097/MCP.0b013e32834db017

  11. Matoulkova P, Pavek P, Maly J, Vicek J. Cytochrome P450 enzyme regulation by glucocorticoids and consequences in terms of drug interactionExp Opin Drug Metabol Toxicol. 2014 Jan 23:10(3):425-35. doi:10.1517/17425255.2014.878703

  12. Lindsay JT, Heaney LG. Nonadherence in difficult asthma - Facts, myths, and a time to act. Patient Prefer Adherence. 2013;7:329-36. doi:10.2147/PPA.S38208