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The Side Effects of Advantage Flea Treatment

 by simone on 07 May 2014 |
12 Comment(s)

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It’s true, honestly Jon Snow you can not stop your beloved pets from fleas and lice simply by wrapping them up in cotton wool… coats that is. Oh brave, handsome, silly Jon Snow.

Luckily for Jon and the rest of us, leading treatment Advantage is readily available. It can be used on dogs, 7 weeks or older, and cats 8 weeks or older, as well as rabbits and ferrets. It is also safe for pregnant and lactating animals. Make sure you talk to your vet if your pet is on medication, if other pesticides are already being used, or if your pet is underweight, elderly or debilitated.

Advantage works as a paralytic to rapidly kill adult fleas and larvae (not the eggs) and therefore breaks the lifecycle of our pets’ most hated foes.

Once applied, the nervous system of fleas and lice is attacked. They are paralysed and die only minutes from coming into contact with Advantage - they don’t even have to bite your pet to be affected. Fleas will stop biting within five minutes of the application, and will be dead within 20 minutes of contact. Advantage kills 98-100% of existing fleas within 12 hours of application and will destroy 99% of flea larvae in the pet's surroundings. 

Advantage is easy to use and remains effective for a month. It is even waterproof so will still work after bathing, swimming, extensive puddle or mud rolling (you know who you are!) or for those wet weather loving, storm chasing pets. 

It is applied through the coat to the dog or cat’s skin and spreads throughout the skin’s oily layer. There are a range of dosages available that depend upon the weight of your pet. Ensure you purchase the correct dosage for your pet and that all directions are followed accurately. Weigh your pet or ask your vet to weigh them - don’t simply guess and apply the dosage you think is correct.

Advantage is an external treatment and must not get into the pet’s eyes or mouth. For small and medium dogs, it is placed out of licking reach on the back between the shoulder blades, and for a cat at the base of the skull. For large dogs over 25kg, the dosage is divided between the shoulder blades, on the back between the hips and at another point in the middle. 

As with any medical treatment, there may be a small portion of animals with individual sensitivities. Always monitor your pet immediately after application and for a few days after. If there are signs of any adverse reaction or if your pet’s health worsens, consult a vet immediately.

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Hair loss and skin irritations
Minor skin irritation is common at the site of application, especially if it is your pet’s first ever treatment. Stiffening or the damp appearance of hair, itchiness, redness or pinkish skin may occur but these are temporary side effects. Occasionally hair loss also occurs. This is usually a one-off and hair will grow back within 1-2 weeks. If the hair loss spreads or doesn’t grow back then consult your vet.

Animals with sensitive skin may develop sores that can bleed if scratched, split or open and then become infected. Check the application site regularly and if these symptoms occur visit your vet. 

Medicinal odour

A low incidence of owners have noticed that their pet has a medicinal-type odour after treatment. This is not dangerous or harmful and will only last a few days to a week after application.

Contact with eyes
If your pet manages to get the treatment in their eyes, flush their eyes immediately with plenty of water and consult with your vet.  

Rare and serious side effects
Serious side effects are rare, usually only occurring in animals with individual sensitivities or allergies to the product’s active ingredients or are a result of accidental ingestion or a mistake in the use of the product.The signs should be noticeable quickly and in all circumstances, immediate veterinary attention is needed if you notice any of the following: 

  • Loss of apetite, increase in thirst, vomiting, diarrhoea or drooling - Remember to apply Advantage as directed, out of reach of your pet’s mouth. The product has a bitter taste that should discourage licking and ingestion. If enough is ingested, it can cause stomach upsets and loss of appetite. Vomiting, diarrhoea, excess salivation, drooling and an increase in thirst indicate excessive ingestion or an adverse reaction.
  • Pupil dilation, eye irritation or increased tear production


  • Breathing difficulties, ataxia (movement problems), stumbling, trembling or seizures


  • Abnormal sleeping, lethargy or non-responsiveness


  • Odd behaviour, depression or hyperactivity

As mentioned, severe reactions are considered to be very rare with Advantage when it is applied as per instructions. As an extra precaution, it is best to observe and separate treated animals for 30-60 minutes to ensure that they do not lick their own application site or that of other animals. Otherwise, Advantage is an extremely easy and effective treatment to make sure your beloved pet doesn’t become high-rise living for fleas and lice. 



Jade  - Comment
Jade 08 Oct 2017Reply
if i feel like my cat is having a reaction, can i wash the area?
Nancy Christie - Comment
Nancy Christie07 Jun 2018Reply
We used Advantage Multi on our otherwise healthy Chesapeake Bay Retruever for flea control. Within 12 hours he was covered with hot spots and within 24 hours he was blind and disoriented. Our vet says to NEVER use this product again. So now what?? My dear dog is now blind. My advice is, if you love your dog dont use this Advantage Multi. It’s poison to more than fleas. Oh and did I mention it causes reproductive issues? So much for my breeding program now. He was the end of a line and now it’s over. No hunting, no swimming. We will learn to work with his blindness. This company needs to stop making this product.
Rebecca Smith - Comment
Rebecca Smith13 Jun 2018Reply
I used this on my 1 yr old Siamese cat, never again. He had hair loss at application site. Hair grew back, so gave him a 2nd app months later. He had a severe reaction, drooling, lethargic, jaw tremors. It all happened 4 to 5 days after applying the Advantage II. I was told if I attempt it again, my pecious Mac will die.
Charles Edward - Comment
Charles Edward14 Jun 2018Reply
My chihuahua is having an extreme reaction to advantage multi administered 2 days ago. Eye swelling, ear irritation, head tilting, diarrhea, lethargy, tremors, rapid breathing. This isn’t the first time he’s had a reaction but it’s abaolutly terrifying. I’ll never give any of my dogs including my other two this poison ever again. We are prepared to take him to the emergency vets, called and have everything arranged Incase his breathing turns rapid again tonight. He’s sleeping now and we are praying it will just wear itself off by tomorrow. This product is 100% toxic. Do not believe what anyone tells you, even vets. My poor little buddy is a victim of this toxic marketing ploy. I’ll never give them this crap ever again and I’ll tell every single person I know what it caused my dog to experience.
Do not give advantage multi to any animal, period.
Louise - Comment
Louise23 Jun 2018Reply
My Binky after advantage is sitting quietly then jumps up runs and hisses I don’t know what to do
Allison Turner - Comment
Allison Turner29 Jun 2018Reply
Advantage dog flea treatment.
Kip - Comment
Kip31 Aug 2018Reply
Advantage II Cat Flea Treatment is dangerous. I used the product on my cat properly....for the correct weight small cat, first application in 5 yrs, indoor cat, no dogs in house to also lick, applied on back of neck, was healthy cat, seperated from other 2 cats till dry. It caused her to have pyriproxyfen poisoning...seizures, partial paralysis from seizures, lethargy, licking, and loss of appetite. The seizures could not be controlled. Note, I also bathed her in mild dish soap when symptoms appeared. I had to put her to sleep. Advantage II manufacturer Bayer would not acknowledge problems but you will find similar cases on the web. Advantage II is not a safe flea treatment option (nor did it work).
Juan arenas - Comment
Juan arenas31 Aug 2018Reply
Pésima experiencia con ese producto , le dio alergia a mi mascota, sacudiendo las orejas todo el tiempo, no puede dormir ni comer , le aplicaron un corticoide y no le ha servido , deben prohibir esa porquería.
Susan - Comment
Susan09 Sep 2018Reply
We used advantage on our Jack Russell 4 days ago. She began scratching herself a lot the day I used it but we just thought it was because she had a bath a day before. She has now thrown up 3 times this evening. Her vomit is clear but there seems to be foamy or a cotton like substance at the top of the vomit. It is a Saturday night so our vet is closed and so are all others. We don’t live near a vet that may be open. Can anyone tell me what we might be able to do. Right now she is shaking and shivering. Thank you for any advice you may have. By the way, she is a young 14 year old and we rarely give her flea treatments. We had been working outside all day Monday and she wanted to be outside with us. We noticed she had a couple of fleas when we got in the house. We decided to use it and I wish we hadn’t.
Briana Harden - Comment
Briana Harden16 Sep 2018Reply
I have been looking online to see reviews and or complaints about this product. My rescue BullPei has had this 2x and no more both times he got huge whelps and cyst like in size and scratched himself raw in many places. I was wondering what other products anyone could recommend. Thank you.
Susan I hop your baby is ok and I am sorry that has happened.
Helen webb - Comment
Helen webb28 Sep 2018Reply
My puppy has suffered from seizures since she had started to have the Advantage
Suzanne - Comment
Suzanne29 Sep 2018Reply
My German Shepherd is having a reaction. He's etheric and won't eat and very thirsty. He is my everything! You are selling an unsafe product! I will bring the biggest lawsuit you have ever seen ! My precious boy better be okay..I will never forgive myself for using this! You need to take this off the market now!

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