FORMULATION: «spot-on» solution for topical administration on the back of the animals (also called pipettes, squeeze-ons, drop-ons, etc.)


CHEMICAL CLASS of the active ingredient(s):


PARASITES CONTROLLED* (spectrum of activity)

* Can be slightly different in some countries: read the product label!


  • Dogs, small ≤10 kg =≤22.9 lbs. bw: 1 pipette with 1.0 mL (equivalent ≥6.0 fipronil and 3.5 mg/kg cyphenothrin)
  • Dogs, medium 10 to 20 kg23 to 44.9 lbs. bw: 1 pipette with 2.0 mL (equivalent to 13.1 - 6.0 mg/kg fipronil and 7.0 - 3.5 mg/kg cyphenothrin)
  • Dogs, large 20 to 40 kg 45 to 88.9 lbs. bw:  1 pipette with 4.0 mL (equivalent to 13.1 - 6.0 mg/kg fipronil and 7.0 - 3.5 mg/kg cyphenothrin)
  • Dogs, very large 40 to 60 kg 89 to 132 lbs. bw: 1 pipette with 6.0 mL (equivalent to 9.8 - 6.0 mg/kg fipronil and 5.2 - 3.5 mg/kg cyphenothrin)

* Can be slightly different in some countries: read the product label!


  • LD50 (acute oral) in rats: ~960 mg/kg (based on fipronil LD50; formulation LD50 n.a. in MSDS)
  • Estimated Toxicity Class according to the WHO: II moderately hazardous (based on the LD50, learn more)

Suspected poisoning? Read the articles on fipronil safety and/or cyphenothrin safety in this site.
WARNING !!!: Never use on cats: cyphenothrin is toxic to cats! Never use on small dogs pipettes approved for large dogs. Learn more aboutspot-ons and their safety.

You may be interested in the following articles in this site dealing with the general safety of veterinary products:


Risk of resistance? YES, low to moderate in:

So far there are only very few confirmed reports on flea resistance to fipronil, 25 years after its introduction for flea control. But there are rumors that the number of product failures is increasing, mainly in the USA. Fleas have developed resistance to several other insecticides (e.g. carbamates, organophosphates and pyrethroids) and are certainly capable of becoming resistant to fipronil as well. Experience shows that prolonged and uninterrupted use of any insecticide on fleas (including fripronil) bears the risk of resistance development. Flea resistance to pyrethroids is widepread worldwide.

There are no reports on resistance of brown dog ticks to fipronil, but moderate resistance to pyrethroids has been reported in several countries (e.g. Brazil, Panama, Spain, USA).

Resistance of mosquitoes to pyrethroids is widespread worldwide, including in the USA. This is mostly not due to the use of pyrethroids on pets, but to large scale spraying of pyrethroids for vector control or pest control in agriculture. As a consequence protection provided by this product against mosquitoes may be lower or shorter than expected.

Alternatives to prevent resistance through product rotation:

*F = effective against fleas; T = effective against ticks.

These alternative products may not be available in all countries, or may not be available as spot-ons.

Resistance of fleas, brown dog ticks, and mosquitoes to carbamates, organophosphates and pyrethroids is not uncommon in several countries, including the USA.

Learn more about resistance and how it develops.


Are the active ingredients ORIGINAL* or GENERICS**?

  • Fipronil: GENERIC (introduced in the 1990s)
  • Cyphenothrin: GENERIC (introduced in the 1980s)

*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.

COUNTRIES where this product is marketed (maybe under another TM): USA
GENERIC BRANDS available? YES, numerous, with a more or less comparable composition.

Click here to learn more about GENERIC vs. ORIGINAL drugs.


PARASTAR PLUS is a generic fipronil+ brand of NOVARTIS (i.e. fipronil mixed with something else). It is only for dogs because cyphenothrin is toxic to cats.

Administered about every 4 weeks fipronil controls established flea infestations and prevents flea populations to develop in the pets environment, but only if all the dogs and cats in the same household are treated against fleas. It also kills several tick species (e.g. Dermacentor spp, Ixodes spp, Rhipicephalus sanguineusAmblyomma americanum, etc).

Fipronil is a broad-spectrum insecticide and acaricide belonging to the phenylpyrazoles introduced in the late 1980s (by RHÔNE MÉRIEUX → MERIAL). It is massively used in pets and agriculture, and also moderately used against household pests and in some countries in livestock too.

Cyphenothrin is a veteran broad-spectrum pyrethroid insecticide and acaricide introduced in the 1980s (by SUMITOMO). It is moderately used in agriculture as well as in public and domestic hygiene, but only scarcely in pets. It is not used at all in livestock. It is effective against fleas, ticks, and mosquitoes. However, resistance of these parasites to pyrethroids is not uncommon, in the USA and elsewhere. This means that protection against these parasites due to cyphenothrin may be lower or shorter than expected.

The combination of two active ingredients of different chemical classes makes theoretically sense regarding resistance prevention in fleas and ticks, because it means attacking fleas through two different mechanisms of action, which is vastly assumed to help preventing or at least delaying resistance development.

Nowadays, after fipronil lost patent protection there are dozens of flea spot-ons for dogs and cats with generic fipronil, alone or in several mixtures with other active ingredients (e.g. pyrethroids, juvenile hormone analogues, amitraz, etc). But not all the brands are available in all countries.

Topical products (mainly spot-ons and insecticide-impregnated collars) have some advantages over systemic products (mainly tablets for oral administration and injectables):

  • Most topical products kill or sterilize the parasites before they bite and suck blood on the pet, whereas systemic products kill or sterilize the parasites only after their blood meal.
  • Topical products cannot be vomited.
  • Spot-ons and collars are very convenient to administer.
  • There is a larger choice of topical products.

But topical products have also some disadvantages:

  • Topical products contaminate the pet's hair coat and it is advisable for children and also adults to avoid contact with the pet for several days after treatment.
  • Topical products may not control parasites in some parts of the pet's body (e.g. the ears, below the tail, between the legs, etc.), whereas systemic products reach the blood-sucking parasites through the blood wherever they are.
  • Efficacy of topical products may be reduced or shortened through exposure to dirt, sun, shampooing, washing, rain, baths, etc., whereas efficacy of systemic products is independent from these factors.

For an overview and a list of the most popular pet antiparasitics for flea, tick, lice and/or mite control click here.


This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics. 

Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.

In case of doubt contact the manufacturer or a veterinary professional.