Why You Shouldn’t Use Frontline on Your Chickens

August 22, 2017

This week I really felt obligated to write this post. If you are like me, you want the very best for your chickens. We hate when our chickens are ailing or have something wrong, like a mite or lice infestation and always like to fix things asap. Like you, I certainly don’t like problems to linger or affect my flock or cause harm. However, sometimes in trying to do good and help our chickens, we can actually end up doing harm. Sometimes we can’t even see the harm that we are doing. Sometimes we can even be potentially harming ourselves without even realizing it. This is what is potentially happening in your flock when you use Frontline. Here’s why.

I have seen many chicken keepers on social media recommending the use of Frontline or other topical products that are used in cats and dogs to kill fleas and ticks.  They work very well even on chickens. But in my opinion from what I have researched, it seems best to rely on other products that have been deemed safe in livestock use.

Before you read on, I guess I should pre-face this post by sharing that I am a nurse practitioner by profession. I will do my best to explain things in the simplest of ways, I cannot cover every minute detail, but I can share with you what is important. This goes for all chemicals and medications you use on your chickens, household pets and you. If you have questions, please post a comment on this post and I will do my very best to answer you.

eggs Tilly's Nest

What is Frontline?

Frontline is the brand name. The active ingredient or generic name of the chemical you are applying to your chickens is called Fipronil. Fipronil is sold under many brand names around the world. Fipronil is in a family of chemicals called phenylpyrozoles and is considered by the USDA to be a Class C chemical meaning that it could potentially cause cancer. It has  been linked to thyroid tumors in rats. Fipronil works by targeting the central nervous system in insects.

What Happens When Frontline is Applied?

When Frontline is applied to the skin or taken orally, it is absorbed to some degree in the body, whether it be avian or mammals. Fipronil is absorbed in mostly in fatty tissues. Over time it is broken down into the blood stream. Studies have shown that significant amounts of finopril remains in the body’s tissues, especially in fat and fatty tissues. Scientists believe that the long half-life reflects the slow release of finopril residues (aka metabolites) and believe that there is a potential for bioaccumulation (build-up) of the metabolites of fipronil in the body over time. Experts believe that a single dose of fipronil can remain in a chicken’s body for up to 8 weeks.

Why do Half Lives Matter?

In medicine, one of the most important questions we ask ourselves will all chemicals and medications is what is the half-life? A half-life tells us how long it takes for our bodies to get rid of half of the dose given. For example, if the half life of a medication is 2 hours and you first took 10 mg, that means that in 2 hours from the time you took the medication, 5 mg will be left in your system, and 2 hours after that 2.5 mg will be in your system and so on until there is none left as long as you do not take another dose. We use this as a guide to help determine the dosing and how often medications should be taken to be safe. Some medications or chemicals have half-lives of a few hours while others can take days or even months. Depending on the dose, we know that fipronil has a first half life that can last up to 8 days. That is a long time. This means that to clear the body, once it is given it will probably take a couple of months for fipronil to be out of a system after the initial application.

As substances are broken down in our bodies, sometimes other substances are created from the breakdown. These area called metabolites. Fipronil has seven metabolites. One of those is a very toxic metabolite that is six time more potent than the original fipronil called fipronil-sulfone (aka Metabolite 46136).


What is LD50?

LD50 is available for all chemicals. Scientists determine at what dose does a certain chemical kill 50% of the subjects tested. It is always given in a mg/kg value.

Fipronil is highly toxic to bees, termites, rabbits, aquatic life, insects and “gallinaceous birds” (aka turkey, grouse, pheasants, quail and chickens). You can see some of the LD50s below:

  • LD50 Oral (given by mouth) RATS 97 mg/kg
  • LD50 Dermal (applied to skin): RATS greater than 2000 mg/kg
  • LD50 Oral (given by mouth) DOG: 650mg/kg
  • LD50 Oral (given by mouth) MICE 95 mg/kg
  • LD50 Dermal (applied to skin): RABBITS 354mg/kg
  • LD50 Oral (given by mouth): CHICKEN 11.3mg/kg (There are no dermal studies available most likely because the oral lethal dose was so low in chickens.)

It should be noted that animals can inadvertently ingest fipronil by the oral route via self-grooming.

But the biggest questions we also need to ask is what about sub-lethal doses. What the the effects of having finiopril in the body with doses lower than those required to cause death? What exactly does finiopril do long-term?

Where does fipronil end up in chickens?

We know that Fipronil ends up in eggs, meat and poultry fat. In one study, they discovered that chickens tend to store the fipronil in the peritoneal fat for up to 8 months! This is why the USDA has limits as to how much can be detected in the poultry products that feed the world. Even some limits have been set by the World Health Organization via CODEX.

  • United States: Poultry Eggs:  Max limit 0.03 PPM ( parts per million)
  • European Union: Poultry Eggs: Max Limit 0.005 PPM (parts per million)
  • United States Poultry Fat:    Max Limit 0.05 PPM
  • United States Poultry Meat:  Max limit 0.01 PPM

Of note, a warning on the Frontline box state that this chemical is not to applied to dogs less than five kilograms. Chickens on average weigh between 2 and 3 kilograms. Furthermore, the estimated daily maximum intake for humans is between zero to 0.00003 mg/kg per bodyweight per day. One scientist relayed that you would only have a problem if you ate eggs contaminated with fipronil everyday.

How do I know how much fipronil is in one cc?

Approximately 98 mg is in 1 cc for the 9.8% concentration of fipronil. So for the dose .67cc tube is a little less than 67 mg.
Some chicken sites that recommend using the Frontline is at a concentration of 0.25cc (25 mg) for bantams and 0.40cc (40 mg) for standard sized chickens. It is unclear where they have obtained their dosing guidelines. Recommended dosing for dogs (not chickens) averages 6.6 mg/kg but it should be noted they have a higher LD50 than chickens.

My Final Thoughts about Frontline:

I wanted you to have this information to make to draw your own conclusions.

There is a reason why the World Health Organization/CODEX regularly tests food sources for contamination of fipronil around the world. In fact, just this month, Europe is recalling eggs tainted with fipronil. Sources believe that a poultry farmer in Europe used fipronil to treat poultry mites in his chickens’ housing. This is because they do not want this chemical in our food supply.  Over 700,000 eggs and egg products in the UK alone have been recalled. The USDA even made a statement that none of the affected eggs were imported into the US and assured the American public that the egg supply in grocers is safe. You can read more about the eggs with fipronil in Europe here.

We know that even with a topical application, fipronil ends up in our chickens’ bodies including the eggs.

With other safe methods for treating poultry mites and lice,why take the risk?
Should you compromise your own health/safety/flock safety for ease of use of fipronil?

Just because it works to control mites and lice, does not mean it is safe.

Just because you can’t see bad things happening to your birds after you apply this it does not mean things are not happening inside that you cannot see.

Personally, I don’t want to eat eggs or feed them to my kids if they have fipronil in them.

You probably should not sell your eggs if you treat with fipronil.

Do your own homework. I’m not entirely sure why veterinarians would recommend this given the readily available data available to them.

Lastly, there is no egg withdrawal period because it is not safe to use in meat and birds that produce eggs. The affected birds in Europe are being culled. Their eggs destroyed along with their bodies. They will not be made available for consumption to people or other animals.



For more information about treating mites with both natural and chemical applications please check out my post on chicken mites.


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32 thoughts on “Why You Shouldn’t Use Frontline on Your Chickens”

  1. Thank you for sharing this information. We were just at our adult poultry club meeting and some of the members were suggesting using front line on the poultry for mites & lice, I have always used natural remedies for our girls. I never trust chemicals.

  2. Thanks for this information. I am a first time chicken mom and have learned so much from your website. I love my girls and want the best for them.

  3. My dog is allergic to Frontline and Advantage, they are poison! He has seizures from it. I switched to FOOD GRADE DIATOMACEOUS EARTH, it is ground crustacians and dusted on the body, not their head of an animal covers them for tick and flea prevention. It is food grade and safe to use. I would assume it may help chickens as well. It is also very affordable. Online or from Feed and Grain stores.

      • I believe that you mean developing silicosis. I discuss this in the my post in DE. When using food grade DE, it is important to not make a dust cloud but sprinkle it. Silicosis takes many years to develop- longer than the lifespan of a chicken. It is more of a potential danger to you- so always apply it in a well ventilated area and cover your nose and mouth when applying. Once applied, it does not go into the air like you would think and it is possible to avoid creating a dust cloud it you sprinkle it close to the surface where you are applying it. It works well and has many benefits. Using many other products can also be hazardous to you too whether “natural”, “organic” or “chemicals”. It’s all about choices and it is great that we have so many to choose from. Chicken keeping rules should never be black or white

  4. I bought a trio of Dark Cornish from a breeder who uses Frontline. I intend to use their eggs for hatching chicks for meat rather than eating the eggs. How long would you wait before hatching the eggs?

    • Unfortunately, I can’t recommend using the eggs or meat but that is my own opinion based on the research that I have done. You might want to call the manufacturer to see if they have any other info or science based recommendations.. I wish I had more information for you.

  5. Thanks for this information. I am so frustrated with the mites on my birds I was considering using one of the topical applications. Just sat down to do some research and your article was the first I read. That’s enough for me, I don’t even need to go to the actual research. I actually thought permethrin was the active ingredient. Could have sworn it was because you can’t let cats around the treated animal for 24 hours because it is toxic to them. Well that’s why I do research before actually acting. I was a nurse also. Thankful that research and know before you do was so ingrained in my education and career. Thanks!

    • Thank you for commenting Mary and I am so happy to be able to share and help. If you email me, I can help you sort out the mite issue with your flock. melissaattillysnestdotcom

  6. So based on the LD test, animals were forced to *drink* frontline and surprise surprise, it killed them, and on *that* basis, you conclude that it mustn’t be used on poultry? How about not pouring it down your chicken’s throats and making them drink it? Frontline spray is the MOST effective means of eradicating scaly leg mites that I have come across in my 40 years as a poultry keeper. But I give one spray per leg and don’t force them to swallow it!

    • Thank you for sharing your thoughts.For me, I know that they are easy to use and work well. I also know that it is the go to for many keepers. But, I want to be sure that folks have information they need to make an educated decision. For us, I know that these types of treatments enter systemically into the bird and do no clear for long periods of time as studies have shown. These chemicals are stored in their fat and do not break down quickly like some other medications do. This means that these chemicals are also found in the eggs that we eat. I don’t want to ingest these chemical in any amount. Please remember, it is all a personal choice and I chose to use other safer options that work for me.

  7. Thank you for the information, as you say it is best to have as much inofrmation as possible to make an educated decision. I have frontline in the house and during early summer I treat the dogs to prevent ticks and fleas etc as recommeded by the vets. I understand it is a chemical based product. I do not re-apply all summer – just use once. I admit i also treat the hens with this product. I put a couple of drops, (literally just a dot) on the back of each of their necks. Again, just once at the early summer to limit the pests. I dont know if this really small amount has a relative effect – its difficult for me to quantify the actual harm this does and how this small amount of fipronil metabolises into the eggs that we eat. I dont sell eggs, they are just for family and friends, but I am worried now that I may be causing harm. Does cooking deplete fipronil?

    • Hello Joanne, Thanks for the thoughtful comment and sharing your thoughts. Cooking when referring to preparing food will not denature residual pesticides in food. This includes those in eggs, meats and produce. Temperatures to denature pesticides require extended time at constant temperatures that would be incompatible with a palatable meal. I hope this information helps with that aspect. As to applying fipronil, I wrote this post to help inform folks and to give alternatives. The choices are yours to make for you and your family.

  8. I use frontline on our backyard hens. I put literally a couple of drops on the back of their necks during early summer, just the once to keep fleas and ticks at bay. I cannot quantify the harm this would cause or how this tiny amont of fipronil metabolises into eggs. Does fipronil survive cooking? I think your article for backyard hen keeping is scaremongering. I agree large quantities should not be used in industrial egg and meat production.

    • There have only been two studies looking at ivermectin use in poultry. Unfortunately, they have not been able to provide recommendations regarding the safety, use and withdrawal period of eggs. So, that being said, I would use it at your own risk but I cannot endorse it or recommend it at this time. I hope this helps.

  9. DE is crap. It doesn’t work. If you think it does, you’re kidding yourself. Sure, some of these products are “off label” since drug companies don’t give 2 caps about chickens & can’t make more money from testing on them, but these pests are just as dangerous to your chickens as are the drugs you use. So it’s really a bad or worse choice. “Natural” insecticides etc don’t work, period. I’ve been raising poultry for 20 years & have tried every natural thing out there & NONE of it works. If your poultry doesn’t have bugs, then you just don’t have a lot of wildlife near you bringing it in. It has nothing to do with your DE or other nonsense.

  10. Thank you for the article. Could you direct me to something more safe to use to help my hens with fleas and lice? You mentioned natural things you use, could you share these with me? My hens need help and I was just about to use frontline!

  11. I used one drop of frontline under 1 wing of each of my chickens in desperation during a severe tick and mite infestation 12 months ago. I wish I had read this article first.
    After googling the withholding period after application I found out I needed to get the eggs tested before eating them to be safe. 4 $250 tests and 12 months later the eggs still contain a level of Fiprinol that is not safe for human consumption. We have thrown away thousands of eggs. Very hard lesson learnt please don’t ever use Frontline or anything that is not specifically designed for chickens on your girls.

    • Where did you get tests? I used Ectoline which was supposed to be safe for chickens and eggs but it does contain Fipronil. I needed something stronger than the natural remedies (and I tried everything). The mites were eating my chickens alive, literally!

  12. I have a female duck who doesn’t get in deep water to bathe. She gets bird mites of some sort and then I have carried them into my house. (Horrible problem before I figured out what it was) Is Frontline plus safe to use on her? She no longer lays eggs and is just a kept as a pet.

  13. What are your thoughts on Elector PSP? Ivermectin? Permethrin? We never had an issue with lice, until we moved. They free range & we are now more in the woods (not sure if more at risk this way) and our chickens got wing lice 🙁 (the kind with the long skinny bodies in the feathers)
    I’ve tried DE dust baths & in coop for weeks, multiple times a week… it hasn’t worked.
    Thank you in advance!


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Sharing an inspired life from the New England seaside. Chickens, Bees, Gardens, Art and Yummy Goodness.