Can You Overdose A Dog On Nexgard? (Understanding The Risks)

can you overdose a dog on nexgard

One essential aspect of dog ownership is flea, tick and mite prevention. These blood-sucking parasites can cause a range of health issues if left untreated.

Choosing a suitable flea and tick treatment is crucial and Nexgard is a popular option among dog owners. However, concerns about potential overdosing and side effects may arise.

Nexgard is generally safe for dogs as long as it’s given in the right dosage based on your dog’s weight. Keep Nexgard under lock and key to prevent any potential accidental ingestion by the dog. Some dogs might see it as a treat due to its highly palatable beef flavor.

In this comprehensive guide, we’ll explore what Nexgard is, how it works, the risk of overdosing, possible side effects, and alternative methods to keep fleas and ticks at bay.

What Is Nexgard?

Nexgard protects dogs from fleas and ticks infestations. It is a tick and flea treatment that comes in chewable tablets and has been approved by the FDA.

It is also used as an off-label drug for treating mange and ear mites in dogs.

This medication is only meant for dogs and should not be given to other pets like your cat.

The active ingredient in the Nexgard chews is Afoxolaner and can only be obtained with a prescription from the vet.

How Much Nexgard Do I Give My Dog?

Nexgard is available in four different strengths, corresponding to your dog’s weight.

According to Nexgard, it is safe for consumption in puppies as young as eight weeks of age but they need to weigh at least four pounds.

The normal dosage for most dogs is one dose of Nexgard a month and is to be repeated preferably on the same day the following month.

This is to be repeated until your dog is clear of the infestation or used during the flea and tick season.

Can My Dog Overdose On Nexgard?

When feeding your dog such medication, it is always very important to follow the stated dosage.

However, mistakes do happen and if you have dogs of different weights at home, you might have given your smaller dog the dosage that’s meant for your bigger dog.

It is easy to go into panic mode when you realised you fed your dog the wrong dose of Nexgard.

A study was conducted on 8-week-old puppies to evaluate the safety of Afoxolaner which is the active ingredient in Nexgard. 1

These puppies were given a dosage that is 5x the recommended amount.

The dogs were given this dosage at six intervals over 126 days.

The results showed that the dogs were still fine at such a high dosage and with no signs of related side effects.

I highly doubt that any dog owner would unknowingly overdose their dogs to such an extent.

A one-off mistake should not have that bad an effect on your dog’s system. But if you noticed the following symptoms:

  • Nausea
  • Diarrhea
  • Lack of appetite
  • Lethargy
  • Excessive drooling
  • Lack of coordination

Please bring your dog to the veterinarian immediately. It might be having an adverse reaction to the overdose and needs to be treated.

There are times when your dog might throw up after taking the medication.

In such scenarios, check to see if the pill is there or if has it been digested.

Do not just feed your dog another dosage if you see a partially digested Nexgard.

What If I Accidentally Overdosed My Dog On Nexgard?

First of all, do not panic.

If you gave your dog two doses instead of one, it should be fine given the findings of the above study.

Make sure to keep a close eye on your dog for the next 48 hours.

The moment you notice any signs of nausea, diarrhea, loss of appetite, etc, seek veterinary attention immediately or call the Poison Pet Helpline.

But if your dog has accidentally ingested the entire box of Nexgard, do not wait any longer and get it to the vet.

The faster you get your dog to the vet, the doctor can induce vomiting in your dog to purge out the Nexgard.

Side Effects Of Nexgard

Even though there have been many reports of Nexgard being a very safe drug, there will be dogs who can be more sensitive to the active ingredients in the medicine.

These active ingredients are potent and are needed to get rid of the parasites in your dog’s body.

Nexgard has warned to not use this on pregnant or lactating dogs as it can be passed on to the puppies.

Dogs with neurological disorders should also refrain from taking Nexgard as it can affect a dog’s nervous system.

Some known side effects that your dog can experience after taking the correct dosage of Nexgard dose:

  • Nausea
  • Diarrhea
  • Dry skin
  • Lethargy
  • Lack of appetite

These symptoms are only temporary and should go away after a few days.

If the symptoms still persist or if you notice any serious adverse reactions, please seek medical advice immediately.

How Does Nexgard Work?

The active ingredients mainly Afoxolaner, destroy the parasites that live on the skin or in the fur of your dog and feed on its blood.

For Nexgard chews to be effective, the parasites must have started to feed on your dog’s blood.

Nexgard will start to eliminate the fleas within the first eight hours and will start to work on the ticks after forty-eight hours.

Afoxolaner will remove adult fleas and ticks by causing their central nervous system to be overstimulated.

This makes Nexgard effective as it prevents the adult parasites from laying eggs which can lead to a more serious infestation.

This causes them to become paralyzed, die and fall off your dog’s body.

Using a flea comb together with dawn dish soap is also a good way to control flea infestations on your dog.

Nexgard also has another product called Heartgard which is meant for preventing heartworms.

Dangers Of Fleas And Ticks On Your Dog

The parasites might be small but if left untreated, they can start to cause serious health problems for your dog.

Ticks can spread Lyme disease which can cause your dog to lose its appetite and become lethargic. In more serious cases, it can even cause kidney failure.

Although fleas don’t spread Lyme disease to dogs, they can transmit the tapeworm parasite into your dog’s body.

Many dogs are also allergic to the saliva of the flea which can cause allergic reactions.

Alternative Ways Of Keeping Fleas And Ticks Off Your Dog

I know of some dog owners who don’t fancy using strong chemicals on their dogs. Most anti-parasite medications contain very potent active ingredients.

Here are some ways that you can try to keep parasites off your dog.

Use An Anti-Flea/Tick Shampoo

Using an anti-flea or tick shampoo on your dog every now and then is a good way to help keep the parasites at bay.

This type of shampoo can help control the itch and destroy the parasites at the same time.

For added measure, use a fine flea comb and go over your dog’s fur to remove any remaining fleas.

To remove ticks, a visual inspection is necessary to manually remove them as they don’t come off by using a comb.

Protective Clothing

If you enjoy taking walks in wooded or grassy areas with your dog, it might be a good idea to put on protective clothing on your dog’s body and paws.

Fleas and ticks usually live in such areas and can latch or jump onto your dog’s fur. Protective clothing can act as the first line of defense.

Make sure that the clothing is comfortable for your dog and doesn’t cause your dog to overheat.

Keep Your House Clean

Do bear in mind that even if you have cleared all the parasites on your dog, they can still live in your home, ready to infect your dog again.

If your dog has had a recent flea or tick infestation, make sure to do a thorough vacuum of your home.

Wash all your dog’s bedding in hot water. If your dog sleeps with you, do the same for your sheets.

Make it a point to do this once a month just to keep your home as parasite-free as possible.

Use A Vinegar Spray

vinegar spray for cats

Parasites like ticks and fleas aren’t fond of odors that are sharp and acidic like vinegar.

By mixing one part apple cider vinegar and two parts water in a spray bottle, it can be an effective way to keep these parasites away from your dog.

Spray your dog with this mixture and comb it into the fur. Make sure to not spray the mixture on your dog’s face as it can be painful.

You can reapply the mixture on your dog’s fur every few hours or when taking a walk in grassy areas.

I prefer to use vinegar over anything citrusy as some citrus fruits can be toxic to dogs.


Keeping parasites like ticks and fleas off and away from your dog is important for their health and well-being.

If you plan to give your dog anti-parasite medication like Nexgard or anything similar, it is always good to have a word with your vet doing it.

Although the majority of these treatments are safe for dogs, there is always a risk of an adverse reaction.


Safety evaluation of orally administered afoxolaner and milbemycin oxime in eight-week-old dogs 1

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