Expiry date of medicines

The shelf life or expiry date of a medicine is the length of time it is effective and safe. This only applies when the medicine is still packaged in the original container and stored correctly.

Commercially packaged medicines that are in their original packaging have expiry dates printed on the package or label so you know when to use them by. This may say:

• expiry
• expiry date
• expires
• exp
• exp date
• use by
• use before.

Note: You can't rely on an expiry date if the medicine has been repackaged or hasn't been stored as recommended by the manufacturer.

Medicines that are repackaged by your pharmacy, may not always have an expiry date but they'll have a dispensing date. It's best not to keep these for any longer than 6 to 12 months after the dispensing date.

No, it's best not to use a medicine that has expired. The shelf life or expiry date of a medicine is the length of time testing has shown it stays effective and safe when properly stored.

• Heat, air, light and moisture can affect the safety of a medicine and how well it works.
• The use of a medicine past its expiry date may result in a lower dose of the active ingredient than that stated on the label (this is particularly relevant to antibiotics).
• It may also lead to an increased risk of contamination (for medicines containing preservatives, such as eye drops or creams). 

The expiry date usually means that you should not take the medicine after the end of the month given. For example, if the expiry date is July 2020, you should not take the medicine after 31 July 2020.

If your medicine has a ‘use by’ or ‘use before’ date instead of an expiry date, this usually means that you should not take the medicine after the end of the previous month. For example, if the use by date is July 2020, you should not take the medicine after 30 June 2020.

If your pharmacist has given you any other instructions about using or disposing of your medicine, you should also follow these. For example, your pharmacist may label a medicine “discard 7 days after opening”. Any medicine that's left in the container after this time should be returned to your pharmacist to dispose of, even if it's within the manufacturer's expiry date.

Some medicines are given a short expiry date due to them being less stable or there being greater risk if they are used for a longer time.

• Prepared antibiotic mixtures: When the pharmacist adds water to powdered antibiotic, it changes the stability of the product. The pharmacist will give it an expiry date of 1 or 2 weeks, depending on the product.
• Eyedrops: These are usually given an expiry date of 4 weeks after first opening the container, because your eyes are particularly sensitive to any bacteria that might get into the eyedrops.

Depending on the medicine, expiry dates may be set for a fixed time after manufacture (unopened) and also during use (opened), but the dates are specific to the container. Different packaging provides different protection and some containers are designed with desiccants (a substance used as a drying agent) to improve stability.

The stability of some medicines depends on where they are stored at home. In New Zealand, this is often bathrooms and kitchens. Because they can have extremes of temperature and humidity, this may not be the best place to store your medicines. Always store your medicines as recommended on the label.

Many medicines are repackaged into blister packs or sachets, to help you remember to take them. When a medicine is repackaged, the new package may not provide the same environment for medicine. This means the manufacturer’s expiry date no longer applies and the pharmacist may add a new, shorter expiry date than that originally set on the package.

If you have medicines that have passed their expiry date, take them to your pharmacist, who can dispose of them safely for you. You should never throw unused or expired medicines in the rubbish bin or flush them down the toilet.