How long do cat medications really last?
Our customer service department gets a lot of emails from cat lovers about every type of question you can imagine about cats. Recently, they forwarded some emails they thought were suited to me, the Irreverent Veterinarian. They knew that I would speak the truth regardless of pet owners or other veterinarians liked it or not.
The topic that I'll address today is… How Long Do Expired Medications Really Last?
All medications have an expiration date on their label. A common question that clients ask is… can they use expired medications for their cats? Are they still good?
There are several factors that can affects the “shelf life” including exposure to light, lack of appropriate refrigeration, and eventually… the chemical instability of the product that can occur with time. This last is the part that can be hard to determine with many products.
It can be nearly impossible to tell when the chemical stability of a product is altered. With some liquid medications - it can be obvious by a color change or change in consistency.
Most veterinarians, physicians and pharmacists well tell you to honor the expiration date on the package. That is the safest way to ensure that the medication is stable. To be honest, many worry that there are liability issues involved if they tell you a medication is okay to use and it is not. This is understandable. I would not want to tell you that a medication is still good and it doesn't work to later find out that it didn't work putting your pet at risk.
Here is some information about the expirations of some medications types:
Pills and Capsules
The expiration of a medication varies based on several factors including the type of medication and the manufacturer. Most oral pills or capsules expire in 1 to 2 years from date of manufacturing. Are they good longer than this?
The honest answer is… probably most oral pill or capsule medications are good for longer than their expiration dates. How long? I don't know. For some medications, I would feel comfortable using on my own pets if they were expired by 1 to 2 years. Longer than 2 years, then I'd replace. If my pet was REALLY ill - then I would NOT use any expired medication. If my pet was… itching and it was 3 am and all I had was some expired Benadryl - I'd probably try it. This is what I would do and does not mean that it is right or wrong.
Liquid Oral Medications
Most liquid medications that are not reconstituted also have a shelf life of 1 to 2 years but once reconstituted (mixed with water - such as powered amoxicillin is mixed with water) - most expire in about 7 to 14 days depending on the specific product. Most will have a longer shelf life if they are refrigerated. However, there are a few liquid medications that are less stable if refrigerated and they should clearly say so on the package.
The shelf life once reconstituted is real. If your vet mixes the liquid and says it expires in 7 or 14 days - then I'd honor that. However, if there is no color or odor change and it is a few days beyond that date - it is probably okay. But this is not a medication that will last long.
Medication still in powder form is probably still good for 1 to 2 years beyond the expiration on the label.
Injectable medications are generally considered less stable and often have shorter shelf lives than oral pill or capsule medication. Some unopened medications can chemically be stable for at least 1 year beyond the expiration. Once opened, it is best to honor the labeled expiration date.
Before you use any liquid medication - make sure that the color is the same and there are no abnormalities. If it was previously clear and it is now cloudy - even if it has NOT expired - I'd question the stability of this medication.
Follow the recommendations on the bottle for best results regarding the shelf life.
There are liquid medications (such as insulin) that are made in smaller vials - so if you are using small quantities in a month - consider asking the pharmacist if it is available in smaller portions (which are generally less expensive) to minimize waste.
Many insulin medications expire 30 days form the date you open them. This is the safest way to use the expiration dates on the package. The consequences to using insulin that is bad can be dangerous.
My Final Thoughts - Should you use expired medications?
If your pet is critically ill - I'd say no - don't use ANY expired medications. Get new medication. It is not worth the risk of a reaction or problem from using expired medications.
What are your thoughts? Email me!
The Irreverent Veterinarian is a columnist that regularly contributes to . The goal is to add a balanced and alternative view of some controversial pet issues. As happens with all of us, veterinarians can't always say what they really think without offending some clients. This commentary allows vets to say what they think and give you, the pet owner, the opportunity to consider another view. All opinions are those of the Irreverent Veterinarian and not the views of and are not endorsed by .