Brand: BAYMEC ® LV = BOMECTIN ® Pour-on


FORMULATION: «pour-on» for topical administration. To be applied along the topline in a narrow strip extending from the withers to the tailhead.

ACTIVE INGREDIENT(S): ivermectin: 10 mg/mL (=1%)

CHEMICAL CLASS of the active ingredient(s): macrocyclic lactone


PARASITES CONTROLLED (spectrum of activity)


  • Cattle: 500 mcg/kg bw, equivalent to 1 ml/20 kg (=22 lb) bw


  • LD50 (acute oral) in rats: >2000 mg/kg
  • LD50 (acute dermal) in rats: >2000 mg/kg
  • Estimated hazard class according to the WHO: not applicable for veterinary medicines

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

Withholding periods (=withdrawal times) for meat & milk (country-specific differences may apply: read the product label)

  • Meat: Australia 42 days (ESI 42 days)
  • Milk for human consumption: NIL

WARNING !!!: Never use on humans, dogs and cats

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


Risk of resistance? YES, reported in gastrointestinal roundworms in cattle in several countries particularly in the following worm species: Cooperia spp and Ostertagia spp.

Based on the very abundant and frequent use of ivermectin and other macrocyclic lactones (with cross-resistance to ivermectin) in livestock it must be assumed that resistance of these roundworms to this chemical class will continue spreading and strengthening in the future.

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it may be due to resistance and not to incorrect use, which is usually the most frequent cause of product failure.

Alternative chemical classes/active ingredients to prevent resistance of gastrointestinal roundworms through product rotation:

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

Resistance of cattle ticks Rhipicephalus (Boophilus) microplus to ivermectin has been reported in several Latin American countries. It is not yet a widespread problem, but nevertheless a warning. Based on the intensive use of macrocyclic lactones on cattle it is only a matter of time for resistance of cattle ticks to these compounds to develop elsewhere unless specific resistance preventative measures (e.g. rotation, IPM, etc.) are taken.

Learn more about resistance and how it develops.


Are the active ingredients of this product ORIGINAL* or GENERICS**?


*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 brand/product is marketed (maybe under another TM): Australia
GENERIC BRANDS available? YES, worldwide by the dozens.

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

For an overview on the most used antiparasitic pour-on brands click here.


BOMECTIN and BAYMEC LV are both Pour-ons for Cattle from BAYER (now ELANCO) based on generic ivermectin. They contain 1% instead of 0.5% ivermectin, which is the most common formulation of ivermectin as a pour-on for cattle, but the recommended dose is the same, 500 mcg/kg bw.

The spectrum of activity is slightly different than the one of the 0.5% ivermectin formulations. The higher concentration has the advantage of a lower administration volume, but may reduce the coverage on the animal's hair coat, which is important for controlling certain external parasites.

Ivermectin was the first macrocyclic lactone introduced in the market in the early 1980s (by MSD AGVET, later MERIAL). It was a milestone and a tremendous progress that revolutionized the control of veterinary parasites. Nowadays there are thousands of brands with generic ivermectin worldwide. It is effective against most species of roundworms that affect cattle and against many external parasites (mainly lice, mites, buffalo flies, etc), but not against tapeworms or flukes.

Besides convenience aspects, the ivermectin pour-on formulations have the advantage over the ivermectin 1% injectables that they also control buffalo flies, biting lice, and cattle ticks, which are not controlled by the 1% injectables.

But it has also disadvantages. In several scientific studies it has been shown that ivermectin administered as a pour-on is not "automatically" absorbed through the skin. Licking (self licking or licking of other treated animals) may account for >50% of the total intake, compared with only about 10% absorbed directly through the skin. This is the reason why a dose of 500 mcg/kg bw is needed after pour-on treatment, compared with only 200 mcg/kg bw after injection. And it has been also shown that intake of topically administered active ingredient in some cattle may be twice as high as in other ones, all treated at the same rate. The reason is that individual cattle show a different licking behavior. An important practical consequence is that the quantity that is finally ingested and is therefore available for the control of gastrointestinal worms depends on the licking behavior of the treated animals. "High lickers" can be overdosed, whereas "low lickers" can be underdosed. And chronic underdosing of animals in a herd may enhance development of resistance to ivermectin in gastrointestinal roundworms. 

Absorption through the skin is also negatively affected by the thickness of the skin and the hair coat, by dust and mud on the coat, by product lost on fences and yards, etc, factors that don't play a role after injection.

In contrast with the ivermectin 1% injectable, the pour-on formulation should not be administered to wet animals, and rain shortly before (up to 6 hours) or after administration can cause product run-off and thus under-dosing. The pour-on shouldn't be administered by strong winds that may blow away part of the product and/or contaminate the workers.

For all these reasons efficacy after pour-on administration is usually less reliable than after injection.

There are also numerous mixtures of ivermectin with other active ingredients, as well as other formulations for parenteral (injectable) and oral (drench, feed additives) administration.

This 1% ivermectin pour-on formulation has a NIL withholding period for milk, i.e. it can be used on dairy cows producing milk for human consumption. This is in contrast with several other 0.5% ivermectin pour-ons (and injectables), which are usually not approved for use on dairy cows in many countries. This is probably related to the recently approved ivermectin MRL in bovine milk (= 10 ppb = 0.01 mg/kg) by some registration bodies (incl. CODEX), which has not yet been adopted everywhere. In the past such an ivermectin MRL for bovine milk was not set at all, and as a consequence any ivermectin residues in milk were illegal. In the absence of an MRL most manufacturers didn't even test the behavior of their ivermectin formulations in dairy cows, i.e. they had no data on milk residues at all: The only possible use recommendation was not to use the product on dairy cows. Now that an MRL is set, manufacturers can generate data and present them to the registration authorities in order to get the approval of a withholding period for milk. Some manufacturers may present such data for their ivermectin products, some may not, or not for all their ivermectin products, for whatever reasons.

Being one of the best antiparasitics ever developed, ivermectin does not control all parasites of livestock. Unfortunately advertising and even the label of some generic formulations in less developed countries often include unsubstantiated claims. To help preventing confusion and misuse it is useful to know that whatever ivermectin 0.5% pour-on formulation (without additional active ingredients) used at the recommended dose of 500 mcg/kg bw DOES NOT CONTROL:

Click here for general information on good practices for the prevention and control of gastrointestinal worms in livestock.


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