WHO Acute Hazard classification: Not listed.

Mechanism of action of Oxantel

Tetrahydropyrimidines, including oxantel, act on the nervous system of the worms as inhibitors of acetylcholinesterase (also known as AchE), an enzyme that hydrolyzes acetylcholine (Ach). Ach is a molecule involved in the transmission of nervous signals from nerves to muscles (so-called neuromuscular junctions) and between neurons in the brain (so-called cholinergic brain synapses). AchE's role is to terminate the transmission of nervous signals where acetylcholine is the neurotransmitter (there are several other neurotransmitters). Inhibition of AchE massively disturbs the normal movements of the parasites.

The bottom line for the parasitic worms is that they are paralyzed and die more or less quickly, or are expelled from the gut because they cannot keep themselves attached to the intestinal wall.

However, whereas other tetrahydropyrimidines such as pyrantel and morantel act on the so-called L-subtype cholinergic receptors (sensitive to pyrantel and levamisole), oxantel acts on the so-called N-subtype cholinergic receptors (sensitive to nicotine and methyridine).

Acute Toxicity and Tolerance of Oxantel

  • LD50 acute, rats, p.o. 980 mg/kg
  • LD50 acute, mice, p.o. 300 mg/kg
  • LD50 acute, rabbit, p.o. 3200 mg/kg
  • Dogs tolerate oxantel very well, due to its low toxicity and its reduced absorption to blood after oral administration.
  • Safety margin of oxantel pamoate in dogs is ~15.

Toxic Symptoms caused by Oxantel Poisoning

  • Most frequent intoxication symptoms are nausea, vomit, diarrhea and loss of appetite.

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

  • Adverse drug reactions after therapeutic doses are similar to those after overdosing (mainly nausea, vomit, diarrhea and loss of appetite), but at a lesser degree.
  • The frequent combination of oxantel with pyrantel is well tolerated and without antagonic effects.
  • Never use tablets (or suspensions, pastes, etc.) for dogs in cats or tablets for large dogs in small dogs. It happens that some users want to save money buying large tablets 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 ingredients that are toxic to cats.

Antidote and Treatment of Oxantel Intoxication

  • There is no specific antidote for oxantel.
  • Treatment consists in supportive and symptomatic measures.

Pharmacokinetics of Oxantel

  • After oral administration oxantel is very poorly absorbed in the gut. This makes it possible that high concentrations of unchanged drug reach the large intestine, which makes it particularly effective against worms in this part of the gastrointestinal system (e.g. whipworms, Trichuris spp).

Environmental Toxicity of Oxantel

  • Not being used in crop pesticides, there is very little information on the environmental fate and toxicity of oxantel.
  • Correct use on dogs and cats is unlikely to be detrimental for the environmental, including coprophagous insects.

Additional information

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

  • Oxantel belongs to the chemical class of the tetrahydropyrimidines.
  • Oxantel is scarcely used in livestock
  • Oxantel is used in human medicines.
  • Oxantel is not used in crop pesticides.
  • Oxantel is not used in public or 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 oxantel.


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.