When it comes to medications, dates matter; or at least that’s what the manufacturers and doctors would have you believe.
With adult heartworms and heartworm disease being potentially fatal, dog owners often wonder, is this the case with dog heartworm medicine too?
While most people are very careful with expiry dates, others have a casual approach. So what if your dogs heartworm preventatives expired last week? Last year? Is it still safe and effective to use?
Well, we weren’t sure either, so our team, including registered vets, put hours of research into finding out the answer.
Today we will uncover the mystery behind expiration dates and determine whether these time limitations actually matter for a heartworm preventative.
KEY TAKEAWAY AND SHORT ANSWER
- A study (1) conducted by the Food and Drug Administration proved that most human drugs are effective even 15 years after the expiry date.
- Although there hasn’t been much research on the stability of expired dog heartworm medicine, we can refer to a study that put the validity of one brand of dog heartworm medication at around 24 months if kept dry at 25-30 degrees c temperature (2).
- Liquid medicine tends to degrade at a rapid rate once the bottle is opened. Studies put the timeframe for its degradation at around 2 weeks.
Does dog heartworm medicine expire? And is it safe to use after expiry? Let’s explore the evidence in more detail.
Can You Give Your Dog Expired Heartworm Medication?
Well, it depends; how far past the expiration date we are talking about.
When it comes to human medication, it’s common for people to use it a few weeks past the expiration date.
And judging by what the studies say, it’s perfectly safe for the most part.
In fact, a study (1) conducted by the Food and Drug Administration proved that drugs are effective even 15 years after the expiry date.
However, this is only true for pills and tablets that have been stored in the fridge for all those years.
On the other hand, liquid medicine degrades and become generally unusable after two weeks, so it’s best to dispose of them after use.
While the overall potency of a drug may decrease over time, this is only by a tiny degree; most of the original effectiveness is still there.
This revelation came after rigorously testing more than 100 drugs only to discover that they had not even lost 10 % of their effectiveness after more than a decade when kept in cool, dry and dark conditions.
Still, we wouldn’t recommend using medication if it’s decades past expiry, especially if it is one crucial for yours or your dogs wellbeing.
If you’re planning on giving expired heartworm medicine to your dog, make sure it’s not in liquid form.
As mentioned before, liquid medicines degrade at a rapid rate and should be discarded two weeks after use.
Also, make sure to avoid using medications that are months or years past the expiry date; a few days past expiry is fine, but a week past is risky.
Although there hasn’t been much research on the stability of expired heartworm medicine, we can refer to a study that put the validity of generic medication at around 24 months if kept dry at 25-30 degrees c temperature (2).
If these conditions are achieved, we can say that the pill should be good for about 2 years.
On the other hand, medicine stored in slightly damper conditions at 40 degrees c will be stable for only 6 months.
These studies lead many people to believe that expiration dates do not imply a date after which the medicine is unusable.
Instead, it appears to be a marketing tactic to keep us permanently restocking your medicinal supplies.
But of course, we can’t verify how much truth there is in that statement, besides those studies, so it’s ultimately up to you how much risk there is.
For something as essential and important to a dog’s life as heartworm medicine, our personal feeling would be to not risk it for our furry friends (whereas for other medicines, we’d feel much more comfortable)
Is it Safe to Give a Dog Heartworm Medications After the Expiration Date?
As long as the medicine is in solid form (Pills, tablets, capsules), it should probably be safe.
However, nobody can guarantee that the medication will be effective or even safe at that point.
The medicine might even become toxic after the expiry date, so giving it to your dog might put him at risk of severe side effects or potential diseases.
To put things simply, do it at your own risk.
Again, we wouldn’t due to the importance of heartworm medicine for our dogs.
Get it wrong and it could be life threatening for our cuddly pals.
Is Expired Heartworm Medication Still Effective?
Expired heartworm medication might still be effective past its expiration date.
However, as mentioned earlier, most medications lose potency after 24 months, provided they are stored in cool, dry conditions. (and this is usually the expiry date on heartworm meds)
If we were you, given all the scientific evidence, we wouldn’t use it if it is older than 2 years or past the expiry on the label (set usually at 2 years from manufacture).
Before that? Again, it’s down to your risk tolerance.
More so, the possibility of side effects and diseases makes using expired heartworm medicine a risky prospect.
After all, you wouldn’t want your dog to suffer just because you don’t want to buy new heartworm medicine, would you?
If the heartworm medicine has long expired and isn’t effective, it’s the same as your dog being left untreated.
You may want to know how long can a dog live with heartworms untreated and make your mind up if it’s worth the risk (spoiler alert – it isn’t).
Heartworm Prevention Medications – FAQ’s
Can You Give a Dog Liquid Heartworm Medication After it Has Expired?
Absolutely not. Liquid medicine tends to degrade at a rapid rate once the bottle is opened. Studies put the timeframe for its degradation at around 2 weeks, so using it past this point is not only ineffective but also detrimental to your dog’s health.
Can You Give a Dog Expired Heartworm Pills?
Studies show that most medicinal pills can retain their stability for at least 2 years if preserved in cool and dry conditions.
So technically, giving your dog heartworm pills should be effective as long the medicine isn’t older than 2 years.
However, no study has been done specifically for dog heartworm pills, so we can’t say for sure that they would be effective and free of side effects past the expiry date.
Does Heartgard for Dogs Have an Expiration Date?
Heartgard Plus comes with a moderately long shelf life of 1-2 years.
So, as long as the pill is less than two years old, it should be perfectly safe and effective for your dog.
Is It Ok to Give a Dog Expired Nex Gard?
The multinational pharmaceutical company Boehringer Ingelheim Animal Health clearly warns us of the dangers of using expired Nex Gard.
According to a study by the CMVA (Commitee For Medicinal Products For Veterinary Use), we should not use Nex Gard or Nex Gard Spectra if the pills are past the mentioned expiry date as their stability is accurate as the manufacturer claims (2).
In general, Nex Gard is effective and safe to use within two years of the manufactured date, after which it may become toxic and unsafe to use.
Summary – Our Final Thoughts
While in some human cases as the evidence shows expiry dates can simply be a precaution, or at worst, a marketing ploy. But expired medication for dogs is far less studied.
It’s true that there are a few studies that insist on the long term effectiveness of medical drugs, even decades past expiry.
However, these studies have only been conducted on a handful of human drugs, without touching on the countless others available on the market – and even less so for animals, including dogs.
In our opinion, based on the evidence, using medications past the expiry date is quite risky, especially for dog medications, and especially for something as serious as heartworm disease.
You never know what kind of side effects might be lurking within these seemingly harmless pills.
At best, it works. At worst, it doesn’t get rid of heartworm larvae or adult heartworms and even make your dog more sick.
So, unless you want to risk your dog not recovering from a potentially fatal disease, we recommend avoiding expired heartworm medicine and other dog medications past their expiration dates.
Heartworm prevention and heartworm infections are a serious disease.
You could perhaps use the meds if they are only a few days past expiry, but this is certainly not a risk-free option and is down to the individual.
In conclusion, we’d rather be safer than sorry when it comes to the heartworm preventive medications we give our furry family members.