Hand sanitizers expire as the alcohol concentration dissolves with time. Once it drops below 60 percent alcohol, it will not be as effective in destroying germs.
The manufacturer estimates how long it would take for the percentage of the current active ingredient to drop below 90 percent of the percentage indicated on the label. That time estimated becomes the expiration date.
However, expired hand sanitizer can still be very useful, especially if it has not yet been opened. Take a look at your hand sanitizer packaging.
You will see a date of expiration which is usually written on top or back. Since the Food and Drug Administration (FDA) controls hand sanitizer it is legally required to have an expiry date and lot number.
This expiry date indicates the period of time that research has verified that the active ingredients of the sanitizer are safe and reliable. Normally the standard is typically two or three years beforehand sanitizer expires.
Sanitizer can still have some effectiveness past its expiration date because it still contains alcohol (the active ingredient). Even if its concentration has dropped below its original percentage, the product is not unsafe to use, but it is less effective, or even ineffective.
In most hand sanitizers – gel and foam – the active sterilizing ingredients are ethyl alcohol and isopropyl alcohol.
The Centers for Disease Control and Prevention (CDC) advises the use of hand sanitizers that contain at least 60 percent alcohol Reliable Source.
The active component of the hand sanitizer, alcohol, is a volatile liquid that quickly evaporates when exposed to air. Although common hand sanitizer containers protect the alcohol from the air, they are not airtight, so evaporation can occur.
As the alcohol evaporates over time, the percentage of the active ingredient of your hand sanitizer decreases which makes it less effective. although hand sanitizer may still work after it has expired, the best option is to replace it after the expiration date has been reached, because it will be less effective.