WHO Acute Hazard classification of pesticides: not listed

Mechanism of action of Nitenpyram

As other neonicotinoids, nitenpyram is an agonist of the nicotinic acetylcholine receptors. It takes the place of the normal neurotransmitter acetylcholine in the receptors, which cannot be deactivated by acetylcholinesterase and remains irreversibly blocked. This leads to an over stimulation of the nerve cells, to paralysis and to death of the affected insect.

These receptors are found in the central and peripheral nervous system of mammals, but only in the central nervous systems of insects. Neonicotinoids bind much more strongly to insect receptors than to mammal receptors. This makes them relatively safe for domestic animals and humans.

Nitenpyram has a systemic mode of action. It is administered orally (tablets) to dogs and cats in, is absorbed into the bloodstream and reaches the fleas when they suck blood. This is in contrast with imidacloprid, the other neonicotinoid most used on dogs and cats, which is administered topically (spot-on) to dogs and cats and has not a systemic mode of action.

Acute Toxicity and Tolerance of Nitenpyram

  • LD50 acute, rats, p.o. 1575 (♀)-1680(♂) mg/kg
  • LD50 acute, mice, p.o. 1281 (♀)-867(♂) mg/kg
  • LD50 acute, rats, dermal >2000 mg/kg
  • As a general rule, dogs and cats tolerate nitenpyram very well.>
  • In dogs and cats, a daily oral dose of 62.5 mg/kg (62.5 x the therapeutic dose) during 7 weeks caused no toxic symptoms.
  • In kittens (8 weeks old), daily oral doses 3x to 5x the therapeutic dose during 6 months cause no significant adverse effects.
  • In dogs and cats concomitant administration of up to 10x the therapeutic dose of nitenpyram with 1x the therapeutic dose of lufenuron caused no adverse effects.
  • In dogs, concomitant administration of 5x the therapeutic dose of nitenpyram and other commercial flea products (fipronil spraycarbaryl powder, pyrethrin sprayimidacloprid spot-onfipronil spot-on, cythioate tablets) according to their label recommendations caused no significant adverse effects.

Toxic Symptoms caused by Nitenpyram Poisoning

  • The primary symptoms of intoxication with nitenpyram and other neonicotinoids resemble nicotine intoxications.
  • Most frequent symptoms are:
    • Fatigue
    • Convulsions
    • Lethargy
    • Difficult breathing
    • Unstable gait
    • Tremor (uncoordinated trembling or shaking movements)
    • Cramps (sudden, involuntary contractions of muscles)
  • In cats, a single oral dose of 125 mg/kg (125x the therapeutic dose) caused salivation (drooling), inactivity, vomit and rapid breathing.
  • Also in cats, single doses of 62.5 to 148 mg/kg (6.2x to 148x the therapeutic dose) caused vomit, soft feces and salivation (drooling), as well as neurotoxic symptoms (tremor, inactivity, stiffness) at the highest dose.
  • As a general rule, young animals are more sensitive to overdosing and react stronger.
  • A possible administration error in dogs is partial administration to small dogs of tabletsapproved for large dogs.
  • A possible administration error in cats is partial administration to cats of tabletsapproved only for dogs.

Nitenpyram Side Effects, Adverse Drug Reactions (ADRs) and Warnings

  • A frequent effect is intense scratching shortly after administration. It is due to flea biting before they are killed.
  • Never use tablets for dogs on cats; never use tablets for large dogs on small dogs. It happens that some users want to save money buying large tablets or spot-ons for treating smaller dogs (or even cats!) twice or more times. The risk of overdosing is considerable, either due to erroneous calculations or to unskilled manipulation. In addition, dog medicines may sometimes contain other ingredients that are toxic to cats.

Antidote and Treatment of Nitenpyram Intoxication

  • There is no antidote for nitenpyram poisoning.
  • Treatment consists in preventing further exposure together with supportive and symptomatic measures.
  • After accidental ingestion stomach lavage as well as administration of active charcoal and laxatives is recommended. Vomiting should not be induced.

Pharmacokinetics of Nitenpyram

  • After oral administration nitenpyram is very quickly absorbed to blood. Effective concentration in blood plasma is reached as soon as 10 to 20 minutes after administration.
  • Absorbed nitenpyram is also quickly eliminated, mainly through the kidneys. Excretion half-time in dogs is about 2-3 hours, in cats about 8-16 hours. 48 hours after administration is almost completely eliminated, about 40% in the form of unchanged nitenpyram, the rest in the form of various metabolites.

Environmental Toxicity of Nitenpyram

  • Nitenpyram is not toxic or only slightly toxic for birds, fish and aquatic invertebrates.
  • Nitenpyram half-life in soil is short, 1 to 15 days depending on the type of soils and other conditions. It does not hydrolyze in acid or neutral water, but breaks down in alkaline water (half-life ~3 days).
  • Nitenpyram does not bioaccumulate.
  • Correct use on dogs and cats is unlikely to result in any significant environmental pollution.

Additional information

Click here for a list and overview of all safety summaries of antiparasitic active ingredients in this site.

  • Nitenpyram belongs to the chemical class of the neonicotinoids.
  • Nitenpyram is not used in livestock.
  • Nitenpyram is not used in human medicines.
  • Nitenpyram is used in some crop pesticides in a few countries
  • Nitenpyram is not used in public and domestic hygiene as a biocide.
  • Click here for General safety of antiparasitics for domestic animals.
  • Click here for General safety of antiparasitics for humans.
  • Click here for General safety of antiparasitics for the environment.
  • Click here for technical and commercial information on nitenpyram.


If you intend to use a veterinary drug containing this active ingredient you must carefully read and follow the safety instructions in the product label.  Always ask your veterinary doctor, or pharmacist, or contact the manufacturer. Be aware that the safety instructions for the same veterinary medicine may vary from country to country.

The information in this page must not be confused with the Materials and Safety Datasheets (MSDS) officially issued by manufacturers for active ingredients and many other chemicals. MSDSs target safety during manufacturing, transport, storage and handling of such materials. This safety summary is a complement to the information on product labels and MSDS.

The toxicity of an active ingredient must not be confused with the toxicity of finished products, in this case parasiticidal drugs or pesticides. Finished products contain one or more active ingredients, but also other ingredients that can be relevant from the safety point of view.

All information in this site is made available in good faith and following a reasonable effort to ensure its correctness and actuality. Nevertheless, no this regarding guarantee is given, and any liability on its accuracy, integrity, sufficiency, actuality and opportunity is denied. Liability is also denied for any possible damage or harm to persons, animals or any other goods that could follow the transmission or use of the information, data or recommendations in this site by any site visitor or third parties.