What to Know About Asmanex (Mometasone)

An inhaled corticosteroid for preventing asthma attacks

Asmanex (mometasone) is an inhaled medication prescribed for the long-term management of asthma symptoms. It belongs to a class of drugs called corticosteroids, which work by reducing inflammation in the airways, decreasing sensitivity to asthma triggers, and lowering the risk of an asthma attack. As such, it is regarded as a controller medication for asthma.

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 healthcare provider 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 (ICS) that alleviates inflammation in the airways⁠. 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.

Two versions of Asmanex are approved by the Food and Drug Administration (FDA):

  • Asmanex HFA for treating asthma in adults and children 5 and over
  • Asmanex Twisthaler for treating asthma in adults and children 4 and over

Asmanex typically is used daily on its own. However, if it doesn't provide sustained control of symptoms, an inhaled long-acting beta-agonist (LABA) may be added.

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

Neither Asmanex HFA nor Asmanex Twisthaler is inherently better than the other. Each device has pros and cons that you should discuss with your healthcare provider in order to determine which version is best for you.

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 by young 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 4

  • Requires once-daily dosing in most cases

  • Generally more side effects

Besides Asmanex, there are several inhaled corticosteroids approved by the FDA to treat asthma, among them:

Note that while daily use of an ICS is the preferred treatment for persistent asthma, some people over 12 who have mild persistent asthma may be able to use inhaled steroids, along with a short-acting bronchodilator, on an as-needed basis when asthma worsens, according to updated recommendations for asthma treatment issued by the National Institutes of Health in December 2020. Talk to your healthcare provider about this change in the guidelines to find out if it affects your treatment.

Off-Label Uses

Although it's not approved to treat chronic obstructive pulmonary disease (COPD), some pulmonologists use Asmanex off-label to help control COPD exacerbations.

Dulera, a combination drug containing Asmanex's active ingredient (mometasone) and formoterol (a long-acting beta agonist, or LABA) is sometimes used to treat severe COPD.

Before Taking

Inhaled steroids like Asmanex commonly are added to an asthma action plan when a short-acting beta-agonist (SABA), also known as a rescue inhaler, is not effective in controlling symptoms and preventing asthma attacks.

According to the American Lung Association, asthma is poorly controlled if:

  • 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.
  • Your asthma is interfering with normal daily activities.
  • Your lung function, as measured by your peak flow or forced expiratory volume in one second (FEV1), gets worse despite treatment.

Although an increase in symptoms or the need to use your rescue inhaler may be enough to indicate adding Asmanex to your treatment plan, your healthcare provider likely will measure your lung function using in-office spirometry and other pulmonary function tests (PFTs) before prescribing the drug.

These tests 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 is a known allergy to mometasone or any of the other ingredients in the inhaler. People with a severe milk allergy should not use Asmanex Twisthaler as it contains lactose powder that may be contaminated with milk protein.

Asmanex can decrease bone mass density and slow growth in younger children and so those using Asmanex should be regularly monitored for impaired growth; note that even if this occurs, any loss in height or bone size is generally minimal, and any slowed growth in children on inhaled steroids is compensated for later on and they attain the same height as children who did not use inhaled steroids.

People with pre-existing osteopenia or osteoporosis should use Asmanex with caution.

With long-term use, Asmanex can cause changes in vision. People with glaucoma or cataracts should be extremely cautious about using it and should undergo regular vision tests to check for changes in eyesight.

Asmanex should also be used with caution by 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 depends of several factors: formulation, age, and whether you have been exposed to corticosteroids in the past.

Asmanex HFA

Asmanex HFA is prescribed as a twice-daily dose for adults and children over 12. It is available in a 100-microgram (mcg) and 200 mcg formulation, as well as a 50-mcg formulation for children between 5 and 11. Your healthcare provider will take your prior corticosteroid use into consideration when determining the dose of Asmanex they will prescribe for you.

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

Children as young as 4 can use Asmanex Twisthaler. Depending on age and prior treatment, 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 does not effectively control symptoms, it can be increased under the direction of a medical professional.

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

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 to feel the full effects of Asmanex HFA or Asnamex Twisthaler. To achieve the optimal response, both should be taken 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's almost time for your next dose, skip the missed dose and continue as normal. Never double up.

Both Asmanex HFA and Asmanex Twisthaler can be stored at room temperature, ideally between 66 degrees F and 77 degrees F, and well out of sight and reach of children and pets. When 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 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 comes 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

As with Axmanex HFA, there can be a slight learning curve when you first start to use 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 fully to completely empty your lungs of air.
  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. Because they are breathed in and therefore directly target the lungs, however, inhaled steroids are less likely to cause side effects than oral corticosteroids that treat inflammation systemically (throughout the entire body).

Asmanex Twisthaler is associated with more side effects than Asmanex HFA. That said, most of the side effects of both drugs tend to be mild and will resolve as the body adapts to the medication. Call your healthcare provider if any side effect persists or worsens.


Among the common side effects of Asmanex HFA and Asmanex Twisthaler affecting at least 3% of users 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 causes oral thrush in fewer than 1% of people who take it. Using a spacer and rinsing your mouth thoroughly after each use can help reduce this risk.


Long-term use of any oral (not inhaled) corticosteroid has been associated with some side effects that can be severe or irreversible. These include eye problems, bone loss, and adrenal insufficiency. Call your healthcare provider 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

If stopped abruptly, Asmanex can trigger withdrawal symptoms and potentially trigger an asthma attack. This is especially true if you take high doses. Do not stop taking the drug without talking to your healthcare provider first, as they may need to reduce your dose gradually over the span of several weeks.

If you experience any infection while on Asmanex therapy, including respiratory infections such as flu or pneumonia, call your practitioner immediately. You may need to stop treatment temporarily until the infection is appropriately treated and cleared. This is especially true of oral thrush, which could get considerably worse if you continue to use Asmanex.

Drug Interactions

Asmanex HFA and Asmanex Twisthaler rely on a liver enzyme called cytochrome P450 (CYP450) for metabolization. Because a wide variety of other drugs also depend on CYP450 in this way, 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 healthcare provider know about any and all drugs you are taking, whether they are 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 at least 30% of people with asthma do not use inhaled steroids as prescribed, which translates to a 34% increase in asthma-related hospitalization.

If you have trouble sticking to your asthma treatment, let your healthcare provider know. They may 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.

11 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.
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By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.