How to Tell If Your Inhaler Is Empty: Counters and Expiry

The most reliable way to tell if your inhaler is empty is to read its dose counter. If it has no counter, keep count of every puff you take and compare that with the number printed on the label. Once the counter reads zero, or you have used the labeled number of puffs, replace the inhaler even if it still sprays. Shaking it, spraying it into the air, tasting it or floating the canister in water are not reliable checks.

Why can’t you tell by shaking or spraying it?

A metered-dose inhaler (the “puffer” type with a metal canister) holds medicine mixed with a propellant. As the medicine runs low, the canister can keep releasing a spray that looks and sounds normal but carries little or no medicine. The US label for the albuterol (salbutamol) inhaler Ventolin HFA explains that the canister keeps working after the counter reaches 000, but the right dose in each puff can no longer be assured.

That is the real risk. You think you are taking your reliever during a flare, but you are mostly breathing in propellant. Because you cannot see the medicine inside, MedlinePlus warns that people who judge by spraying or tasting may keep using an inhaler after it is empty.

How do you read a dose counter?

Many inhalers now have a counter or dose window that counts down as you use them. Two examples from US labels:

Ventolin HFA (albuterol): the counter starts at 204 on the 200-puff size, or 064 on the 60-puff size, and drops with every spray. The label says to refill when it reads 020 and to throw the inhaler away at 000.
Advair Diskus (fluticasone and salmeterol powder): the counter goes down by one with each dose, and the last numbers, 5 to 0, show in red as a warning.

Counters look different from one device to the next, and some are marked only in steps of 10 and do not change after every dose, so read the leaflet that came with yours. Get in the habit of glancing at the counter before each use, and order a replacement when it reaches the warning zone, not when it hits zero.

Priming also uses puffs. Ventolin HFA, for example, needs 4 test sprays into the air before first use, and again if it has not been used for more than 14 days or has been dropped. Those sprays come off the counter too.

How do you count puffs if your inhaler has no counter?

Some inhalers still have no counter, so you need to keep track yourself. MedlinePlus describes a simple counting method that works like this:

Find the total number of puffs on the canister or box. Many hold 200, but check yours.
Work out how many puffs you take each day. For example, 2 puffs twice a day is 4 puffs a day.
Divide the total by your daily puffs. A 200-puff inhaler used at 4 puffs a day lasts about 50 days.
Write the start date on the canister, or put it in your phone, and note when it should run out. Refill well before that date.

Take priming sprays off the total as well. This method works for a preventer you use on a set schedule. A reliever you use only when needed has no daily pattern, so count each puff as you take it. A tally on the box or a note on your phone works. When you get close to the total, switch to a new one.

Why is the float test not recommended?

You may have heard the old trick of dropping the metal canister into a bowl of water: if it sinks it is full, and if it floats it is nearly empty. It does not work well. How a canister sits in water depends on its size, design and contents, not just on how much medicine is left, so different products float in different ways. MedlinePlus lists floating the canister with spraying and tasting as checks that do not really work.

There is a second reason to skip it. MedlinePlus says not to wash the canister or put it in water. When you clean a metered-dose inhaler, you take the canister out first and rinse only the plastic mouthpiece, then let it air-dry.

How do you know when Rotacaps or other dry powder inhalers are empty?

Dry powder inhalers come in two main kinds.

Capsule devices

With capsule inhalers, such as Asthalin Rotacaps used in a Rotahaler, each capsule holds one dose. Your supply is simply the number of capsules left in the strip.

The thing to check is whether each capsule was fully used. After you inhale, open the device and look at the capsule shell. If powder is still inside, follow your leaflet, which may tell you to breathe in again. Some capsule devices are built around this: the US label for the Spiriva HandiHaler tells users to breathe in twice from each capsule to get the full dose. The same label says not to leave capsules open to air, not to store them inside the device and not to swallow them.

Multi-dose powder inhalers

Devices that hold many doses inside, such as a Diskus (called Accuhaler in the UK), a Flexhaler or a Turbuhaler, have a built-in counter or dose window. Treat zero as empty. Keep these devices dry. The Advair Diskus label says never to wash it and to throw it away 1 month after opening the foil pouch, or when the counter reads 0, whichever comes first.

Do inhalers expire?

Yes. Every inhaler has an expiration date on the canister, box or pouch, and labels such as Ventolin HFA’s say not to use it after that date. Some devices also have a shorter “use within” period once the foil wrapper is opened, like the 1-month limit for the Diskus. Check your leaflet, and write the opening date on the device if it has one of these limits.

Temperature matters too. Ventolin HFA is labeled for storage at 68°F to 77°F (20°C to 25°C), with short periods between 59°F and 86°F (15°C and 30°C) allowed. A glove box in summer or a car in winter is a poor place to keep a spare. Check the dates and counters on spares regularly, for example when you change your clocks.

Why should you keep a spare reliever inhaler?

Albuterol and levalbuterol (levosalbutamol) are quick-relief medicines that open the airways during a flare, and finding your inhaler empty in the middle of an attack is dangerous. A practical setup looks like this:

one reliever you carry every day, in a bag, pocket or backpack
a backup at home, at work, or with the school nurse for children
a refill ordered as soon as the main inhaler’s counter enters its warning zone

If you buy your reliever online, allow for shipping time. Delivery to the US takes about 6 to 15 days, and customs can add delays, so order before you are down to the last few puffs. The Asthalin Inhaler contains albuterol (salbutamol) and is made and licensed in India by Cipla. It comes in packs of three or more, from $30. See other options in our asthma inhalers range, and our guide to types of asthma inhalers explains which inhaler does what. Like all prescription asthma medicines, a reliever should be used under your doctor’s care.

Featured in this article

Asthalin Inhaler

Starting at just $30.00

A spare is a safety net, not a reason to use more. If you are going through reliever inhalers faster than before, your asthma needs a review, not just another refill. The Ventolin HFA label notes that needing more doses than usual can be a sign that asthma is getting worse.

When to see a doctor

See your doctor soon if:

you need your reliever more often than usual, or you are finishing canisters faster than before
your reliever does not seem to work as well or its effect does not last as long
asthma symptoms wake you at night
you are not sure how to use your device or read its counter (a pharmacist can also check this)

Call 911 or get emergency care if you are very short of breath, cannot speak in full sentences, your lips or fingernails look blue or gray, or your reliever is not helping. Do not keep puffing on an inhaler you suspect is empty while your symptoms get worse.

Frequently asked questions

Does an inhaler still spray when it is empty?

Often, yes. A metered-dose canister can keep releasing propellant after the medicine is used up, so a spray is not proof that medicine is left. Go by the counter or your puff count.

How many puffs are in an inhaler?

It depends on the product. Many albuterol inhalers hold 200 puffs, and some smaller ones hold 60. The number is printed on the canister or box.

Can I use an inhaler after its expiration date?

Labels say not to. Replace an expired inhaler, and check the dates on any spares you keep in a bag, desk or drawer.

Do priming sprays use up doses?

Yes, priming sprays leave the canister and are counted. Ventolin HFA’s 200-puff canister, for example, starts its counter at 204. Prime only when your leaflet says to, such as before first use, after a long gap or after dropping it.

This article gives general information and does not replace advice from your doctor or pharmacist. Prescription medicines, including asthma inhalers, should be used under a doctor’s care. Always follow the leaflet that comes with your inhaler.