Effipro DUO Spot on

Effipro DUO Spot-On for Cats and Dogs


Liquid Spot-on

Active ingredient

Fipronil, pyriproxifen

Frequency of use

Every 4 weeks

Minimum age/weight

10 weeks / 1kg cats , 2kg dogs)


Fleas (adults), fleas (immature), ticks

What is Effipro DUO?

Effipro DUO is a non-prescription spot on flea and tick treatment. It contains Fipronil, which kills adult fleas and ticks. It also contains pyroxiprofen, which works to stop insects developing from their eggs.

What does Effipro DUO do?

Effipro DUO contains two active ingredients, fipronil, and pyroxiprofen. Let’s break down how they work:

  • Fipronil: This ingredient is a broad-spectrum insect-killer and tick-killer. Once applied, it quickly spreads across your pet’s skin and hair follicles through the skin oils. Fipronil targets the nerves of fleas and ticks, stopping them from functioning normally, which eventually kills them.
  • Pyroxiprofen: This is an insect growth regulator. It stops female fleas from reproducing and prevents eggs from hatching and growing properly, therefore breaking the lifecycle.

What is Effipro DUO for?

Effipro DUO helps control:

  • Fleas: Effipro DUO kills adult fleas, putting an end to the itching and discomfort. It also interrupts the growth cycle of the fleas, getting an infestation under control more quickly than an adulticide-only medication. It prevents new infestations for 5 weeks after application in cats, and 7 weeks after application in dogs.
  • Ticks: Effipro DUO kills ticks, preventing potential diseases transmitted by these parasites. It keeps killing ticks as they latch for 1 week in cats, and 2-4 weeks in dogs.

What are the side effects of Effipro DUO?

Like all medicines, Effipro DUO can have side effects. These include:

  • Hair loss – either at the application site or generally
  • Itching – either at the application site or generally
  • Scaly skin at the application site
  • Drooling – very rarely, drooling may occur
  • Increased sensitivity to stimuli such as noise and touch – rarely, cats treated with Effipro DUO become hyper-sensitive to stimuli such as sound and touch, making them appear nervy and jumpy
  • Depression – It’s very rare, but cats can appear depressed (hiding, less responsive than normal) after Effipro DUO.
  • Respiratory problems – In less than 1 in 10,000 cats, breathing difficulties can happen after Effipro DUO
  • Vomiting – in very rare cases, cats might vomit after Effipro DUO.

Remember, these side effects are mostly mild and the more serious ones are very rare. Effipro DUO has lots of benefits treating and preventing fleas, helping to reduce allergic reactions to fleas, and helping to stop the spread of tick-borne and flea-borne diseases. If you are worried about the side effects of Effipro DUO, talk to your vet who will be able to suggest a different medication.

Which pets is Effipro DUO not suitable for?

There are some pets that should not receive Effipro DUO. These are:

  • Puppies and kittens under 10 weeks of age.
  • Cats weighing less than 1kg
  • Dogs weighing less than 2kg
  • Sick or debilitated animals
  • Other species (especially rabbits, as this medication can be fatal for them)
  • Pets who are pregnant or feeding puppies/kittens
  • Pets who are known to be allergic to the medication or any other ingredients

How to give Effipro DUO safely

  • Follow instructions carefully: Always use Effipro DUO according to the instructions on the label. This includes the right dose, species, and frequency. You will need to know your pet’s up-to-date weight in order to purchase the correct treatment for them.
  • Check weight and age: Effipro DUO shouldn’t be used in cats or dogs less than 10 weeks of age, unless otherwise recommended by a vet. Cats should weigh at least 1kg, dogs at least 2kg.
  • Never split doses: Always use the right size for your pet. Never try to split a larger dose between several pets.
  • Apply to the back of the neck: Always apply where your pet cannot lick it off. This is usually from between the ears to just above the shoulder blades – the middle of the back of the neck is a good place to put it. 
  • Ensure animals do not lick each other after treatment: If you have pets that groom one another, keep them apart until the product has dried.
  • Do not allow animals to bathe or swim: You shouldn’t bathe animals or allow them to swim for at least 2 days after application, as this washes off the product, damaging the environment and preventing it from working properly for your pet. If your pet is bathed more frequently than monthly, you shouldn’t use Effipro DUO.
  • Check with your vet if your pet is on medications: If your pet is on any medications, you should talk to your vet about the best options for flea prevention.
  • Storage and Handling: Store Effipro DUO according to the instructions on the label, usually in a cool and dry place. Make sure it’s out of reach of children and other pets. Dispose of used pipettes immediately to ensure children do not have access to the product.
  • Report any accidental overdose to your vet immediately: If you have mistakenly given too much Effipro DUO, report it to your vet as soon as you realise the error. They may recommend blood tests, intravenous fluids, or monitoring, depending on the severity of the overdose.
  • Use gloves when applying: Some people have allergies to this product, and it can cause skin irritation. Use gloves when applying.
  • Do not handle pet until application site is dry: Care should be taken not to touch the product, and children shouldn’t be allowed to play with pets until it is completely dry. It’s usually best to apply Effipro DUO in the evening so that it can dry overnight. Pets who are regularly treated should not be allowed to sleep in children’s bedrooms. 
  • Furniture warning: This product can damage furniture, especially leather, paint, and varnished surfaces. You should avoid your pet coming into contact with these until the application site is completely dry.

Effipro DUO FAQs

How long does Effipro DUO last?

Effipro DUO lasts for 2-7 weeks, depending what you’re protecting against and whether you’re using it for a cat or dog.

For cats, Effipro DUO protects against fleas for 5 weeks and ticks for 2 weeks.

For dogs, Effipro DUO protects against fleas for 7 weeks and ticks for 2-4 weeks.

Effipro DUO needs re-applying every 4 weeks to be effective. It is not suitable for applying more frequently than this, so if you are having problems with ticks you should switch to a treatment with a longer protection for ticks.

What is the difference between Effipro and Effipro DUO?

Effipro contains fipronil, Effipro DUO contains fipronil and pyroxiprofen. The added pyroxiprofen means Effipro DUO stops fleas from reproducing and the immature fleas from developing, so it will get rid of an infestation more quickly.

However, it’s worth noting that you will still need 12 weeks of continual treatment to get rid of a flea infestation, even with pyroxiprofen. To find out why (and ways to get around this), see our free online resource.

How do I know fleas are dying after treatment?

It’s unusual to see fleas dying after treatment, as they’re so small, although you might find slow, ill-looking fleas. So how do you know fleas are dying? When a flea treatment is working it’s rare to see fleas 2-3 days after their treatment. If you find fleas after this, it’s possible that these fleas have only just jumped onto your pet – because they haven’t yet bitten your pet, they haven’t ingested the poison. Another alternative is that the flea treatment isn’t working. If you are persistently finding living fleas on your pet after treating them, you should troubleshoot using the information in our Free Flea Treatment Course.

Effipro DUO Datasheet

All drugs have a manufacturer’s datasheet, which gives information about the drug’s use and possible side effects. There is usually one in your Effipro DUO box, but if you have lost it you can click on the button below to be taken on an online version.

Struggling with a flea problem?

No pet should have to suffer with fleas. But it can be hard to beat them. In this FREE resource, our vets explain why flea treatments fail and explain how to choose a flea treatment that suits your pet. Add it to your cart now!

Please note that the information contained herein is provided for informational purposes only. Although it has been written by a vet, we cannot consider the individual nature of your pet’s problems so it does not constitute veterinary advice. If you have questions about your pet’s medication or their health you should contact a vet, who will be able to help.