Is it “ok” to use expired fish meds? (Let me explain)

[SwimmingBlueberry]

So I used to have like 4 nano tanks about a year ago and of course being a fish keeper for 2 years you accumulate some fish meds. Well a year ago I got out of the hobby and traded it for the reptile hobby. Well now I’m doing both. I have a container full of opened medications and I’m wondering if they are ok cause most of them expired last year. 
 

here’s the meds I have 

ich x (big full bottle only used 1-3 times) expired 4/23

Methylene blue expired 11/23

X2 kanaplex expired 7/23

metroplex 7/23

melafix and pimafix expired unknown 

full packet of maracyn expired 9/23

 

i really hate to buy more meds..

 

[Tlindsey]

On 6/19/2024 at 10:17 PM, SwimmingBlueberry said:

So I used to have like 4 nano tanks about a year ago and of course being a fish keeper for 2 years you accumulate some fish meds. Well a year ago I got out of the hobby and traded it for the reptile hobby. Well now I’m doing both. I have a container full of opened medications and I’m wondering if they are ok cause most of them expired last year. 
 

here’s the meds I have 

ich x (big full bottle only used 1-3 times) expired 4/23

Methylene blue expired 11/23

X2 kanaplex expired 7/23

metroplex 7/23

melafix and pimafix expired unknown 

full packet of maracyn expired 9/23

 

i really hate to buy more meds..

 

Not to sure but the methylene blue may be good for atleast a couple more years. 

[SwimmingBlueberry]

That’s the one medication I only had to use one time! And it spilled in a bag so now I only have a tiny bit lol

[Colu]

On 6/20/2024 at 4:10 AM, SwimmingBlueberry said:

That’s the one medication I only had to use one time! And it spilled in a bag so now I only have a tiny bit lol

With medication they become less effective after the expiry date given  the fact that some of them have been expired for over a year I would bin them 

[TOtrees]

This is a good question. While I'm not a doctor or vet, or wet vet, I did more than my share of time in biology and chem, and that time helps to inform how I view meds.  I don't have to quote or cite the below, because I just made it 🙂

Caveat: the rate at which product effectiveness diminishes is almost certainly not linear, at least not over the entire 100 to 0 percent range. More likely, it's stable for a period of time, then diminishes curvilinearly, and tails off to the right. Like this:

Returning to your question, can you use expired meds? My point in making the above is to illustrate that the med doesn't have a magical off switch, at which point it stops working. If the medicine remains 100% up to the expiry date (maybe it's 110 or 120 % effective prior to that?), then days and weeks after the expiry it's still going to be 90 or 95 % effective (picking relative percentages to make a point). Tweaking the dosage would bring the amount of viable (not expired) active ingredient back up to the medically proven concentration. But you don't know how much extra to add, and no one will stick their neck out to tell you.