Both oxfendazole and fenbendazole are efficacious against gastrointestinal lungworms and roundworms of livestock, adults, and L4-larvae of the significant species for example, of the genera Bunostomum, Haemonchus, Ostertagia, Oesophagostomum, Nematodirus, Teladorsagia, Cooperia, Trichostrongylus, Dictyocaulus, Trichuris, etc., including against arrested larvae of some of the species.

[7][8][9] This drug works effectively against the main parasitic roundworms and tapeworms of dogs and cats.

[10][11] The drug offers a small residual effect in ruminants unless and otherwise it is delivered by using a slow-release device.

This essentially means that on a single administration it will help in killing the parasites which are present in the host during the time of treatment and also prevent against re-infestations for some more days but not weeks or months.

However, high oral doses can causes intoxication resulting in loss of appetite, diarrhea, fever, cramps, nausea, vomit and convulsions, hepatic and epicardial hemorrhage, allergic reactions etc.