Full Guide: Safest Flea And Tick Prevention For Dogs

safest flea and tick prevention

Practicing natural flea and tick prevention for your dog is challenging. So what do you do when trying to go natural for your pup’s tick treatment and tick control just isn’t working? And you’ve got a flea or tick infestation beyond what you and your dog can handle. All that scratching … and you both just want to kill ticks and get relief … FAST! 

You might want to throw in the towel and turn to the heavy hitter tick treatments … like pharmaceutical flea and tick prevention. But don’t feel defeated. Here’s what you need to help you wade through all the options to find the safest flea and tick prevention for dogs.

We’ve ranked the different types of flea and tick preventives in reverse order of safety … from riskiest to safest. 

#1 Definitely Not Safe – Oral Flea And Tick Preventatives

These are the worst offenders and most dangerous to use on your dog. They’re taken orally, usually as a tasty chew for your dog. These drugs contain isoxazolines. And they’re usually only available by prescription.

Many of these meds contain a class of ingredients called isoxazolines. They’re non-competitive GABA (gamma-aminobutyric acid) receptor antagonists. This means they bind to chloride channels inside the flea or tick. In plainer English, they block nerve signals … which paralyzes and kills the bugs.

How Oral Flea And Tick Preventatives Work

When you give your dog isoxazolines, they work systemically. This means they’re absorbed into his blood and they affect the entire body. When fleas and ticks feast on your dog’s blood, they eat the chemicals … and become paralyzed and die.

The Food and Drug Administration (FDA) has alerted pet owners and veterinarians that there’s potential for neurological damage when using drugs in the isoxazoline class. The reactions include muscle tremors, impaired movement, lack of coordination and seizures.

After reviewing as many brands of oral chews and tablets as we could find, here’s a list of  active ingredients you’ll want to watch for on the label.

Active Ingredients In Oral Flea And Tick Meds

The first list below are chemicals used solely to prevent flea and tick bites and infestations. They’re potent and dangerous enough. They include acaricides that are pesticides poisonous to ticks and mites. Ectoparasiticides are to treat external parasites like fleas, ticks, lice, mites and flies.

The second list shows antiparasitic chemicals also known as anthelmintics. This means they expel parasites like worms. These are dewormers added to the flea and tick products. You should avoid this combination of drugs because it increases the risk to your dog. Flea and tick medications are often given for 8 months … or longer if you’re in a warm climate. But you should never treat your dog for worms unless he has them. And if he does, there’s no need to give a dewormer for the entire flea season.

So if you see ingredients from the first list AND the second list, you’re getting unnecessary and harsh dewormers. This is on top of  risky flea and tick medications. Some claim to prevent as many as 6 different insects and worms … including fleas, ticks, lice, worms and heartworm. This is a lot of unnecessary medication and can lead to some pretty serious side effects … especially when your dog doesn’t need the extra meds!

Ingredients Against Fleas And Ticks

  • Afoxalaner – a member of the isoxazoline family
  • Fluralaner – for systemic use and also a member of the isoxazoline family; it is the single active ingredient found in one brand of chews that lasts for 12 weeks!
  • Sarolaner – an acaricide and insecticide also belonging to the isoxazoline family
  • Lotilaner – an ectoparasiticide belonging to the isoxazoline family, with a 1 month duration
  • Spinosad – made from soil bacteria that is toxic to insects and found in garden insect spray
  • Lufenuron – controls flea infestations by preventing the hatching of eggs, and prevents the flea shell from developing

Unnecessary De-Wormers Often Included

  • Milbemycin oxyme – used as a broad spectrum antiparasitic for heartworm, and internal parasites including hookworm and roundworm
  • Moxidectin – an anti-parasitic to control heartworm and intestinal parasites
  • Pyrantel – an anthelmintic, or dewormer
  • Praziquantel – an anthelmintic used for parasites like tapeworms

The Problem With Oral Flea And Tick Products And Meds

The problem with poisoning fleas and ticks is that you’ll also poison the host … and that’s your dog! So If you want to find the safest oral flea treatment for dogs … The answer is, there’s no such thing.

The theory behind isoxazolines is that your dog is a lot larger than a flea … so they assume a little bit of poison won’t hurt him. And that might sometimes be true. But what happens if you give your dog a small amount of this poison every month for years? The manufacturer (Zoetis in one study) doesn’t actually know what happens … because safety studies were only done for 3 months. 

Side Effects Of Oral Flea And Tick Meds

But dog owners have reported some pretty serious side effects. They’re often neurological in nature, like seizures. That’s because most of these products kill the pests by attacking the nervous system and paralyzing them. Side effects from these drugs include:

  • Tremors
  • Seizures
  • Ataxia – stumbling, falling, uncoordination
  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Skin irritations
  • Lethargy

These symptoms show that dogs are being poisoned along with their pests. They’re suffering the same neurological issues that kill the fleas and ticks. So every dog is at risk. And you only need look through social media at dedicated pages where heartbroken owners describe the seizures their dogs suffered … before they died.

Even the inactive ingredients in chews are undesirable. They may not be listed, but can include things like “natural” flavors that aren’t natural, starches, sugars and preservatives … to name a few.

#2 Pretty Unsafe: Flea And Tick Collars

The second riskiest category is impregnated flea and tick collars that your dog wears all day and all night for as long as 8 months. So they’re right under your dog’s nose all the time. The absorption of chemicals is through the skin. And unlike oral flea and tick preventives, your dog isn’t supposed to eat these. But accidents happen. A lot of them, according to reports from the Environmental Protection Agency (EPA). 

Even if your dog doesn’t slip out of his collar and chew on it, another dog at the park or in the family might. It can easily come off and become a chew toy. And that’s a highly toxic chew toy. Just read about the ingredients that follow. Unlike oral flea medications, these collars might not need a prescription. That means a household could also have several on hand that could easily fall into the wrong paws.

The EPA shows that from January 2012 through mid-June 2020, it received incident reports about just one brand … Seresto collars … documenting 1,698 pet deaths. And more than 73,000 injuries rated as minor, moderate or major. There were almost 1,000 reports of harm to humans. That includes a 12-year-old boy who had seizures and vomiting after sharing his bed with a dog wearing the collar.The product registration document filed with the EPA warns that children should avoid contact and shouldn’t play with the collars

Active Ingredients In Flea And Tick Collars

  • Flumethrin – a synthetic pyrethroid, in the same category as insecticides like permethrin. Pyrethroids paralyze the insects’ nervous systems. 
  • Pyrethroid – a synthetic chemical class of insecticides isolated from the chrysanthemum. Permethrin is one of those insecticides. Permethrin poisons the central nervous system.
  • Deltamethrin  – another synthetic version of pyrethrin from the chrysanthemum. It’s an insecticide used in malaria control and as a coating on mosquito nets. 
  • Imidaclooprid – it’s a neonicotinoid insecticide used for crop protection and in pet insecticides. 
  • Tetrachlorvinphos – it’s an insecticide. It’s used as a medication, insecticide and nerve agent as a weapon. Used as an oral larvicide in livestock and against flies in dairy. Kills fleas, ticks, lice, chiggers, mites, spiders and wasps.
  • Methoprene – slow acting insecticide that interferes with the growth cycle of an insect to prevent it from maturing and reproducing.
  • Pyriproxyfen – used in pesticides, it mimics a natural hormone in insects and prevents eggs from hatching. It’s used to control fleas, cockroaches, ticks, ants, carpet beetles and mosquitoes. 

How Flea And Tick Collars Work

The chemicals in these collars release into the area around your dog and into his skin. Then the chemical circulates through the bloodstream. When a flea or tick draws blood from your dog it’s infected with the chemical and dies. This takes place over several months while your dog wears the collar. 

These collars are for external use only … but how does your dog know that? He cleans himself by licking his skin and fur. He’ll easily ingest the collar’s pesticides that disperse onto his fur and skin over several months … through his whole body.

Your dog is a mammal and they tolerate pyrethroid insecticides such as flumethrin much better than insects like fleas. For insects the toxicity is 1,000 times higher. But keep in mind a flea or tick only bites once. Your dog has constant exposure through his skin and breathing, or he may have open wounds … so the impact can be far more serious.

Side Effects Of Flea And Tick Collars

The chemicals used in these collars are neurotoxins, endocrine disruptors and immunosuppressants. They can cause these signs and symptoms …

  • Nausea, vomiting
  • Seizures
  • Diarrhea
  • Salivation
  • Tremors and Convulsions
  • Hyperactivity and hypersensitivity to touch or sound
  • Inflammation
  • Kidney and liver damage
  • Organ toxicity
  • Disrupts proper functioning of antioxidants
  • Thyroid damage
  • Abortions and birth defects

Beware Fake Flea Collars

Flea and tick prevention is big business so it’s no surprise that there are counterfeit products vying for a piece of the pie.

The well-known Seresto flea collar brought in $300 million in sales in 2019. This success attracts plenty of knock-offs. You need to watch for fake name brand collars and off-brands as well. The bogus collars might not protect your pet from fleas and ticks. In fact, the ingredients might be even more harmful than chemicals in the real thing. They can cause severe illness as well as burns. The genuine manufacturers claim that some of the reports of injuries to pets are due to the fake collars.

If buying a Seresto collar, get it from a reputable source, like a vet supply company. Don’t buy it from an unknown online source or even Amazon or E-Bay! You can go through the Bayer website, the manufacturer, to get a list of local and online authorized retailers.

If you believe you have a fake collar, you need to call Bayer directly. Give them the lot number and serial number of the product and find out if they made it.

Seresto In The News
In 2021, the US House Subcommittee on Economic and Consumer Policy called on Elanco, manufacturer of the Seresto collar, to temporarily recall its collar. The company refused.

After a 16-month investigation, the committee released a 24-page report in June 2022. It’s titled: Seresto Flea and Tick Collars: Examining Why A Product Linked To More than 2,500 Pet Deaths Remains On The Market. Reported numbers from June 2020 have been updated to 98,000 (up from 75,000) incidents and 2,500 (up from 1,700) pet deaths.

The subcommittee made three main recommendations:

  • Recall Seresto collars and begin canceling the collar’s registration
  • Strengthen the EPA’s scientific review process
  • Improve incident data collection

In a statement a year ago, Elanco noted more than 25 million collars were sold in the US. The incident report rate for all adverse events was .3%. The simple math is that 750,000 animals had some type of reaction to the Seresto collar since 2012. So even a low percentage of problems is a lot of harmed animals

#3 Safer But Still Risky 

There are two types of products in this category. 

I. Spot-On Flea And Tick Prevention

The third highest risk category is the pharmaceutical topical treatments commonly called spot-ons. That’s because they’re applied to your dog by dropping the medication onto spots along your dog’s back. In general, you’ll want to use the ones with the fewest ingredients. Just like the oral preventives, avoid spot-ons with extra ingredients that cover a range of pests. If your dog isn’t infested with several pests he doesn’t need the additional treatment and the toxins that go with it. 

Active Ingredients In Spot-Ons

  • Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. It disrupts the insect’s central nervous system and causes hyperexcitation of its nerves and muscles.
  • Imidacloprid – a systemic insecticide that acts as an insect neurotoxin to attack the central nervous system of sucking pests like fleas. It’s also toxic to honeybees and mimics the effects of nicotine on insects. 
  • Permethrin –  as described in #2. Also used to treat lice.
  • Pyriproxyfen – as described in #2. 
  • Moxidectin – as described in #1. 
  • Dinotefuran – in a class of neuro-active insecticides known as neonicotinoids that are chemically similar to nicotine. It does not require ingestion by the insect to be effective. 
  • (S)-methoprene – an insecticide that stops growth and development. It prevents egg-laying and hatching, so pests don’t reproduce.
  • Selamectin – an antiparasitic and antihelminthic insecticide used on dogs to treat heartworms, fleas, ear mites, sarcoptic mange. It’s a dewormer and an insecticide.

How Spot-On Flea And Tick Prevention Works

Topical flea and tick preventives get applied as liquid along a dog’s back, usually between the shoulder blades. They’re absorbed into the skin, then chemicals circulate into the bloodstream and travel into the sebaceous glands. The active ingredient releases and moves through the glands that lubricate a dog’s coat with oil. When an insect draws blood from your dog the chemical infects it and it dies.

Like all products given to your dog by mouth or bloodstream, they remain in your dog’s system. Some products are longer lasting in your dog than others. Shorter duration is a good thing. That means it leaves your dog’s system more quickly … and you may not need to re-apply it. 

But your dog licks himself to clean himself. And the chemicals circulate through his body. So even though application was  on his back, no matter where he licks, the chemicals get secreted through his skin throughout his body.

Side Effects Of Spot-Ons

The EPA’s Pesticide Division, found that fipronil enters the body and can be contained in the fat, organs, urine and feces of dogs. The EPA also found that most of the reactions to fipronil involved systemic as well as application site, digestive, neurological and behavioral disorders. The most common clinical signs were:

  • Skin reactions like hair loss, itching, and redness
  • Dermatitis
  • Sores
  • Irritation
  • Hair changes at the application site
  • Neurological issues like uncoordinated movement 
  • Lethargy

Brief exposure to (S)-methoprene can cause mild or moderate skin irritation in humans. Higher doses in dogs can cause:

  • Vomiting
  • Dilated pupils
  • Changes in behavior
  • Changes in breathing 
  • Changes in muscle control 

Imidacloprid has caused skin irritation in pet owners after applying spot-on products to their animals.

PRO TIP If you’ve chosen to use a medicated flea and tick spot-on, you may not need the full dose. You can give your dog just a drop or 2 of the spot-on treatment. Start with a little to see if you are getting results. You can always increase the dosage. 

II. Medicated Flea And Tick Shampoos And Sprays

This is a second entry in the Safer But Still Risky category. Medicated flea and tick shampoos and sprays contain harmful chemicals, just like the other types of preventives. Using them might help keep the pests away … but you’re also exposing your dog to more toxins.

Active Ingredients In Flea And Tick Shampoos

Pet shampoos are already filled with toxic ingredients like phthalates, formaldehyde, neurotoxins like methylisothiazolinone, plus propylene glycol and sodium benzoate. They contain artificial scents and colors and a few dozen more ingredients you’d rather not use on your dog.

Medicated flea and tick shampoos include active ingredients like these:

  • Permethrins – as described in #2.
  • Piperonyl Butoxide – works alongside a pesticide to increase its effectiveness. It interrupts enzymes in an insect’s body to allow insecticides to penetrate. 
  • N-Octyl bicycloheptene dicarboximide – enhances the pesticide properties of other insecticides.

These represent 1% of the total ingredients. And the rest are the ingredients of a standard shampoo … toxins and all.

Any Shampoo Kills Fleas

There’s no benefit to giving your dog a bath with a medicated flea and tick shampoo. Giving your dog a bath with a shampoo made of natural ingredients will drown fleas as effectively as dousing him in a medicated shampoo …. without the harmful ingredients.

PRO TIP Don’t forget, if your dog has fleas, you need to treat your home and yard for fleas, as well as your dog. 

#4 Safe Flea And Tick Prevention For Your Dog

Now that you know about the riskier products, here are some safe, natural ways to prevent fleas and ticks on your dog. Using natural solutions is the best choice if you want to use flea medicine that does not cause seizures or other harmful effects.

But first, a caution. Label reading doesn’t stop when you reach for natural flea and tick prevention. Even with so-called natural products, always look at the ingredients … because some say they’re natural when they’re not really. One example is a spray has the word “organics” in the name. But it lists some inactive ingredients you don’t want … like sodium benzoate. It can cause inflammation in animals, free radicals that lead to oxidative stress and allergic reactions.

So let’s look at the safest flea treatment for dogs.

Safe Flea And Tick Repellents

Natural sprays should contain as few ingredients as possible. Watch out for changed formulas. Two products that used to contain just two ingredients (cedar oil with hydrated silica) now include extras like sodium lauryl sulfate and mineral oil … additives to avoid.

When you make something yourself, you can control your ingredients. Here  are recipes for flea and tick sprays using essential oils that are safe for your dog.

DNM RECOMMENDS: Kin+Kind offers 100% Organic Natural Flea & Tick Spray to protect your dog from pests and soothe itching from bites. Buy Kin+Kind Flea + Tick Prevent! now …

Essential Oils

Essential oils can often come to the rescue when it comes to repelling fleas and ticks. You can use essential oils to make your own repellent, collars, bandanas and shampoos. remember that essential oils are very potent, so never use them undiluted on your dog. One drop of a plant’s essential oil is more than 75 times stronger than its herbal counterpart. Just 3 to 6 drops of essential oil to an ounce of carrier oil like sweet almond oil  is a good ratio.

And not all essential oils are safe for dogs. Some oils are toxic to dogs so you want to be careful when choosing them. Remember that your dog’s sense of smell is hundreds of times more sensitive than yours. 

Here’s a list of oils to use and oils to avoid from canine herbalist Rita Hogan. They are specific for flea and tick prevention. 

Safe Essential Oils For Dogs

  • Cedarwood
  • Grapefruit
  • Rosewood
  • Myrrh
  • Opoponax
  • Bay leaf
  • Lavender
  • Lemon
  • Lemon eucalyptus
  • Eucalyptus (radiata)
  • Palmarosa
  • Cedar (atlantica)
  • Clary sage
  • Peppermint (don’t use near your dog’s face)
  • Rosemary (avoid for dogs with seizures)

Avoid These Unsafe Essential Oils For Dogs

  • Tea Tree
  • Cinnamon
  • Clove
  • Garlic
  • Pennyroyal
  • Sweet Basil
  • Birch
  • Anise
  • Wintergreen
  • Oregano
  • Thyme

Collars and Bandanas

You can create your own flea and tick collar by using diluted essential oils as instructed above. Then add a few drops to a fabric collar or bandana that your dog will wear. But use them for outings only. Take them off when your dog comes indoors so he’s not breathing in the oils 24/7.

Flea And Tick Tags

There are several brands of tags that work energetically. They start working after 2-3 weeks on your dog’s collar and must stay on your dog 24/7. (If you take the collar off at night, keep it where your dog sleeps so it remains activated.) They usually last for a year. Supplement with a natural spray when going out in the woods. You’ll find lots of options online and at natural pet stores. 


Amber is a petrified resin, which is a byproduct of trees. Amber flea collars come from stones of amber. They’re milky in color and craggy, and strung on a thread and fastened with a leather or cloth buckle. Baltic amber (from the Baltic sea) has a particularly high acid content of 8% making it the most used. The acid content in amber combines with static electricity produced from the stones rubbing against your dog’s fur. This is what repels fleas and ticks. Many say that the longer a pet wears an amber collar, the better it works.

There’s wide variety in the quality and durability. You should choose your size carefully. And be sure you’re buying from a reputable seller who only uses pure Baltic amber.

Safe Flea and Tick Shampoo

If your dog is prone to picking up fleas, you can bathe him more regularly during the height of flea season. (And don’t forget to keep vacuuming your house daily.) Choose shampoos made with natural products and no chemicals. 

Look for ingredients like these in one safe flea and tick organic shampoo for dogs: aloe vera juice, coconut oil, shea butter, olive oil, sunflower oil, jojoba oil, sweet orange essential oil, neem oil, rosemary extract. It’s quite a difference from what you’ll see in medicated flea and tick shampoos … or even standard pet shampoos.

Or make your own. Add a few drops of a safe, bug-repellent essential oil to unscented castile soap to make a safe flea and tick shampoo for your dog.  

Clean Up Your Dog’s Lifestyle

A healthy dog isn’t a good host for fleas and ticks. Start your dog’s journey to good health before flea season begins. Here are some lifestyle changes to start with:

  • Feed a whole food, raw meat diet.
  • Avoid chemicals, pesticides, fertilizers and toxic cleaners.
  • Minimize vaccines and pharmaceutical drugs.
  • Add finely diced fresh organic garlic to your dog’s meals every day. Allow it to sit for 10 minutes after dicing. Give a large dog up to 2 cloves a day. Smaller dogs can have up to 1 clove. 
  • Sprinkle food grade diatomaceous earth on your dog’s fur from his ears to his tail to dry out ticks and fleas.

PRO TIP If you hike in the woods with your long-haired dog, you’ll want to check for ticks after each trip. To do this you can use a hair dryer on its cool setting to blow his fur. The fur will part so you can see through to his skin and spot any ticks that might be crawling around or latched on. 

Beware Of What The Packages Don’t Say

As you’ve seen above, you’ll need to do a lot of reading between the lines when it comes to flea and tick prevention. Here’s a reminder of some things to beware of.

  • Duration of prevention. Avoid the longer-lasting 8 to 12 week products. Longer prevention means a more potent product and longer time in your dog’s system.
  • Additional de-worming or heartworm drugs. Don’t treat worms your dog doesn’t have! And if he does, look for natural solutions. And heartworm meds don’t prevent heartworm. They only treat heartworms already in your dog, so address that topic separately. (Read more at the link below).
  • Multiple active ingredients. That’s a sign that it’s addressing other parasites in addition to fleas and ticks.
  • Inactive ingedients. Often these aren’t on the label. But they could be as much as 90% or more of the product. It’s best to look for a product that lists all the ingredients.

Watch Your Dog For Side Effects

This comes at the end but it’s a critical part of dog ownership. You should always watch your dog like a hawk for any changes in his day to day behavior. 

If you choose to use any of these products, please be especially diligent. Monitor your dog daily. That means for several months or longer, depending on the duration of the product. Once it’s in his body, you can’t remove it. And that’s especially true of the long-lasting oral flea and tick preventives.

Side effects may take time to appear. You’ll want to watch for:

  • Neurological signs like incoordination, staggering, tremors, seizures
  • Skin irritation such as redness, scratching or other signs of discomfort
  • Gastrointestinal signs such as vomiting or diarrhea
  • Lethargy or agitation

If you notice anything unusual, call your holistic veterinarian immediately.

Walking the natural path takes a lot of courage. It takes even more courage to admit you might need some extra help. Along with that help comes information to help you make the best decision possible for your dog. 


What is the safest flea and tick medication for dogs?

The safest flea and tick medications are those that avoid harmful chemicals and focus on natural prevention methods. Topical treatments and collars may pose risks and should be used with caution. Consult with a holistic veterinarian to choose the safest option for your specific dog.

What flea and tick treatment was killing dogs?

Oral flea and tick preventatives, particularly those containing the isoxazoline class of drugs, have been linked to serious side effects in dogs, including neurological damage such as seizures and muscle tremors, as indicated by FDA warnings.

Does my dog really need flea and tick prevention?

Yes, all dogs need flea and tick prevention to protect them from various diseases these parasites can transmit. Natural methods can be effective and are recommended to minimize exposure to potentially harmful chemicals.

What are the neurological side effects of Nexgard?

Nexgard, which contains the isoxazoline class of drugs, has been associated with potential neurological side effects in dogs. These can include muscle tremors, ataxia (lack of muscle coordination), and seizures, as highlighted by FDA alerts.


Chrustek, Agnieszka, et al. Current Research on the Safety of Pyrethroids Used as Insecticides. Medicina (Kaunas). 2018 Sep; 54(4): 61.

Becskei, Csilla, et al. Efficacy and safety of a novel oral isoxazoline, sarolaner (Simparica™) in the treatment of naturally occurring flea and tick infestations in dogs presented as veterinary patients in Europe. Veterinary Parasitology. Volume 222, 30 May 2016.

Robb, Erika L., et al. Organophosphate Toxicity. StatPearls Publishing. 2021 Jan.

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