How do you use pMDI? A Step-by-Step Guide

Studies show that over 70% of patients with asthma or COPD use their inhaler incorrectly, which can significantly reduce the medication's effectiveness [1.7.1]. Learning how to use pMDI devices properly is crucial for managing respiratory conditions.

Quick Summary

Mastering the correct technique for a pressurized metered-dose inhaler (pMDI) is essential for effective treatment of asthma and COPD. Key steps include priming, shaking, coordinating breath, and holding your breath.

Key Points

• Priming is Essential: Always prime a new pMDI, or one that hasn't been used recently, by shaking and spraying it away from you [1.5.3].

• Slow and Steady: pMDIs require a slow, deep inhalation over 3-5 seconds, starting at the same time you press the canister [1.5.5].

• Hold Your Breath: After inhaling the medicine, hold your breath for at least 10 seconds to allow it to deposit in the lungs [1.2.5].

• Spacers Improve Technique: Using a spacer or holding chamber removes the need for perfect hand-breath coordination and improves drug delivery [1.3.2, 1.6.5].

• Shake Before Every Puff: Shake the inhaler vigorously for 10-15 seconds before each use to ensure the medication is properly mixed [1.2.5].

• Exhale First: Always breathe out fully before placing the inhaler in your mouth to make room for a deep inhalation [1.7.4].

• Rinse After Use: If using a steroid inhaler, rinse your mouth with water and spit to prevent oral thrush [1.2.5].

What is a pMDI?

A pressurized metered-dose inhaler, or pMDI, is a device that delivers a specific, measured amount of medication directly into the lungs [1.5.2]. It consists of a pressurized canister containing the medication suspended in a propellant, fitted into a plastic mouthpiece actuator [1.8.1, 1.5.3]. For decades, pMDIs have been a cornerstone of treatment for respiratory conditions like asthma and Chronic Obstructive Pulmonary Disease (COPD). The main challenge with pMDIs is the need for coordination between pressing the canister and inhaling the medication, a step where many users make mistakes [1.8.3].

Before You Start: Priming Your pMDI

Priming your inhaler is a critical step to ensure you receive the full dose of medication. It's necessary when the inhaler is new, has been dropped, or hasn't been used for a week or more [1.5.3, 1.5.4]. The medicine and propellant can separate over time, and priming ensures they are properly mixed [1.5.3].

1. Remove the cap and check the mouthpiece for any foreign objects [1.2.5].
2. Shake the inhaler vigorously for about 5-10 seconds [1.5.2, 1.5.6].
3. Point the inhaler away from your face [1.5.3].
4. Press down on the canister to release a spray. The number of sprays needed for priming varies by brand; new inhalers often require four sprays, while re-priming may only need two. Always check the instructions that came with your specific device [1.5.3, 1.5.4].

How to Use a pMDI: The Standard Technique

Correct technique is vital for the medication to reach deep into your lungs where it's needed.

1. Prepare: Stand or sit up straight to allow your lungs to expand fully [1.3.4]. Remove the mouthpiece cap [1.2.3].
2. Shake: Hold the inhaler upright and shake it well for 10-15 seconds before each puff [1.2.5].
3. Exhale: Breathe out fully and gently, away from the inhaler, to empty your lungs [1.2.5, 1.7.4].
4. Position: Place the mouthpiece between your teeth without biting and close your lips to form a tight seal [1.2.3].
5. Inhale and Actuate: As you begin to breathe in slowly and deeply through your mouth, press down firmly on the canister one time [1.2.5, 1.5.5].
6. Continue Inhaling: Keep breathing in steadily and deeply for about 3-5 seconds [1.5.5]. This slow, deep breath is crucial and is often where errors occur [1.7.4].
7. Hold: Remove the inhaler from your mouth and hold your breath for at least 5-10 seconds, or for as long as is comfortable [1.2.2, 1.2.5]. This allows the medication to settle in the airways.
8. Exhale Slowly: Breathe out slowly, away from the inhaler [1.2.2].
9. Wait: If a second puff is prescribed, wait about 30 seconds to a minute, shake the inhaler again, and repeat the steps [1.2.2].
10. Rinse: If you used an inhaler containing a steroid, rinse your mouth with water, gargle, and spit it out to reduce the risk of side effects like thrush [1.2.2, 1.2.5].

Using a pMDI with a Spacer

A spacer, or valved holding chamber, can make using a pMDI much easier and more effective, especially for children and those who struggle with coordination [1.6.5]. It holds the medication cloud after it's released, so you can inhale it without perfect timing [1.3.2].

1. Assemble: Remove the caps from the inhaler and spacer. Shake the inhaler and insert its mouthpiece into the opening at the end of the spacer [1.4.2].
2. Exhale: Breathe out gently, away from the spacer [1.4.6].
3. Inhale: Place the spacer's mouthpiece in your mouth, sealing your lips around it. Press the inhaler once to release a puff into the chamber [1.4.1]. Then, breathe in slowly and deeply over 3-5 seconds [1.4.2]. If the spacer makes a whistling sound, you are breathing in too quickly [1.4.2].
4. Hold: Hold your breath for 10 seconds [1.4.2].
5. Tidal Breathing (Alternative): An alternative to the single breath is tidal breathing. After pressing the inhaler, simply breathe in and out normally through the spacer mouthpiece for about 4-6 breaths [1.4.2, 1.4.6].
6. Repeat: If another puff is needed, wait 30-60 seconds before repeating the process [1.4.6].

Comparison: pMDI vs. Dry Powder Inhaler (DPI)

While pMDIs are common, they aren't the only option. Dry powder inhalers (DPIs) are another major type.

Feature	Pressurized Metered-Dose Inhaler (pMDI)	Dry Powder Inhaler (DPI)
Inhalation Technique	Requires a slow, deep inhalation coordinated with actuation [1.6.5].	Requires a quick, forceful inhalation to draw the powder out [1.6.5].
Propellant	Uses a chemical propellant to push the medicine out [1.5.3].	Breath-actuated; contains no propellant [1.6.5].
Coordination	High level of hand-breath coordination required [1.8.1].	No coordination needed; just a powerful inhalation [1.6.5].
Spacers	Should always be used with a spacer for optimal delivery [1.6.5].	Not used with spacers [1.6.5].
Moisture Sensitivity	Generally not sensitive to environmental moisture.	Powder can clump if exposed to moisture or if you exhale into the device [1.3.1, 1.6.5].
Dose Counter	Many do not have a built-in dose counter [1.6.5].	Most have a built-in dose counter [1.6.5].

Common Mistakes and How to Avoid Them

Studies reveal that a vast majority of users make at least one error [1.7.4]. Awareness is the first step to correction.

• Poor Coordination: Pressing the canister before or after inhaling. Fix: Use a spacer to eliminate the need for perfect timing [1.3.1].
• Incorrect Inhalation: Breathing in too fast. pMDIs need a slow, steady breath. Fix: Practice a slow 3-5 second inhalation. A spacer that whistles can provide feedback if you're too fast [1.4.2].
• Forgetting to Exhale First: Not fully breathing out before inhaling means your lungs don't have enough space for a deep breath of medication [1.7.4]. Fix: Make a conscious effort to empty your lungs before each puff.
• Not Holding Breath: Exhaling too soon prevents the medicine from settling in the airways [1.7.4]. Fix: Count to 10 in your head after inhaling.
• Not Shaking the Inhaler: Medication can settle, leading to an inconsistent dose [1.3.2]. Fix: Shake vigorously for 10-15 seconds before every single puff.

Cleaning and Storing Your pMDI

Regular cleaning prevents medication buildup and blockages. Clean your inhaler's plastic actuator at least once a week.

1. Disassemble: Remove the metal canister. Do not get the canister wet [1.2.5].
2. Rinse: Rinse only the plastic mouthpiece and cap under warm running water [1.2.5].
3. Dry: Shake off excess water and let it air-dry completely overnight [1.2.5]. A wet actuator can cause medication buildup.
4. Reassemble: Put the canister back inside once the actuator is dry.

Store your inhaler at room temperature, away from extreme heat, cold, or moisture [1.5.4].

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Disclaimer: This article provides general guidance. Always follow the specific instructions from your healthcare provider and the manufacturer of your inhaler device. For more information and resources, you can visit Asthma + Lung UK.

Conclusion

Mastering how to use your pMDI is as important as the medication itself. By following these steps for priming, using, and cleaning your device—and by considering a spacer to simplify the process—you can ensure that you are getting the full benefit of your prescribed respiratory therapy. Regular practice and periodic technique checks with your doctor or pharmacist are essential for long-term success and better disease control.

Frequently Asked Questions

Why do I need to shake my pMDI before using it?

You need to shake your pMDI because the medication is a suspension in a propellant. Shaking it for 10-15 seconds mixes the two, ensuring you get a consistent and correct dose with each puff [1.2.5, 1.3.2].

What is a spacer and should I use one?

A spacer (or holding chamber) is a tube that attaches to your pMDI. It holds the medication cloud after you spray it, making it easier to inhale the full dose without needing perfect timing. They are highly recommended to improve medication delivery and reduce side effects [1.6.5, 1.3.2].

How do I know if my pMDI is empty?

Many pMDIs do not have dose counters. The best way is to track your doses. Divide the total number of puffs in the canister (written on the box or canister) by the number of puffs you take each day to know how many days it will last. Do not rely on floating it in water, as this is inaccurate [1.9.2, 1.6.5].

What's the most common mistake when using a pMDI?

One of the most common and critical errors is poor coordination—not pressing the canister and inhaling at the same time [1.8.3]. Other frequent mistakes include not exhaling fully before use and inhaling too quickly [1.7.4].

How long should I hold my breath after inhaling?

You should hold your breath for 5 to 10 seconds, or for as long as you can comfortably do so. This allows time for the medication to settle deep within your lungs [1.2.2, 1.2.5].

Do I need to clean my inhaler?

Yes, you should clean the plastic actuator of your pMDI at least once a week. Remove the metal canister, rinse the actuator with warm water, and let it air-dry completely to prevent blockages [1.2.5].

What is the difference between a pMDI and a DPI?

A pMDI uses a propellant to push the medicine out and requires a slow, deep breath. A Dry Powder Inhaler (DPI) is breath-activated and requires a quick, forceful inhalation to get the medicine out. Spacers are used with pMDIs but not DPIs [1.6.5].