Brand: 4FLEAS


FORMULATION: «tablets» for oral administration


CHEMICAL CLASS of the active ingredient(s): NEONICOTINOID


PARASITES CONTROLLED* (spectrum of activity): Fleas


  • Cats and dogs, up to 11 kg bw: 1 tablet with 11.4 mg nitenpyram (equivalent to 11.4 to 1.0 mg/kg nitenpyram)
  • Dogs 11.1 to 57 kg bw: 1 tablet with 57.0 mg nitenpyram (equivalent 5.1 to 1.0 mg/kg nitenpyram); >57 kg administer 2 tablets.

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


  • LD50 (acute oral) in rats: n.a. for the tablets. 1575-1580 mg/kg for the a.i. nitenpyram
  • Estimated Hazard Class according to the WHO: not applicable for veterinary medicines

Suspected poisoning? Read the article on nitenpyram safety in this site.

WARNING !!!: Never use on cats or small dogs tablets approved for large dogs. Learn more about tablets 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 in: fleas, mainly the cat flea, Ctenocephalides felis

So far there are no reports on flea resistance to nitenpyram. However, fleas have developed resistance to several other insecticides (e.g. carbamates, organophosphates and pyrethroids) and are certainly capable of becoming resistant to nitenpyram as well. Experience shows that prolonged and uninterrupted use of any insecticide on fleas (including nitenpyram) bears the risk of resistance development. Consider also that nitenpyram is a neonicotinoid, the same chemical class as imidacloprid, the a.i. of the ADVANTAGE-range of spot-ons from Bayer.

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 tablets.

Resistance of fleas 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 of this product ORIGINAL* or GENERICS**?

  • Nitenpyram: GENERIC (introduced in the 1990s)

*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: UK
GENERIC BRANDS available? Yes, this is a generic version of ELANCO's (former NOVARTIS) CAPSTAR.

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


JOHNSON'S 4FLEAS is a generic version of ELANCO'S (formerly NOVARTIS) CAPSTAR with nitenpyram from NOVARTIS (now ELANCO). Whereas most topical products need 1 to 3 days to kill all fleas on a pet, CAPSTAR starts killing fleas in less than 1 hour after administration and 4 hours later >99% of the fleas have been killed. However, it has no residual effect, i.e. protection against re-infestations is not longer than 1-2 days, in contrast with about 4 weeks for most spot-ons and other tablets against fleas.

Nitenpyram is a nenonicotinoid insecticide introduced by in the 1990s (licensed from TAKEDA by NOVARTIS, now ELANCO). It is a broad-spectrum insecticide but without efficacy against ticks or mites. It is moderately used in agricultural pesticides, modestly in pets but not at all in livestock. It has a systemic mode of action, i.e. after oral administration it gets into the blood of the pet and reaches the fleas during their blood meal. 

Systemic products (tablets for oral administration, injectables) have several general advantages over topical products (spot-on, insecticide-impregnated collars, shampoos, soaps, sprays, powders, etc):

  • They do not contaminate the pet's hair coat: avoiding contact with the pets after administration is not necessary for children or adults.
  • The active ingredient reaches the parasites through the blood, everywhere in the pet's body, whereas topical products may leave some body parts (e.g. the ears, between the legs, etc.) insufficiently protected.
  • Efficacy is independent from exposure to dirt, sun, shampooing, washings, rain, baths, dirt, etc., whereas topical products can be washed away, or broken down by sunlight, etc.

But they have also a few disadvantages:

  • The parasite has to bite and suck blood first before it is killed or sterilized.
  • Orally administered products (tablets, suspensions, pastes, etc.) may be vomited and treatment needs to be repeated.
  • Administration of tablets may be less convenient than administration of spot-ons.
  • The choice of products for oral or injectable administration is smaller than for topical administration.

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.