Thank you ozepat - got this off poultrykeeper.com in the U.K. - Ivermectin - An anti-parasite medication, effective against most worms (not tapeworm), mites and some lice including scaly leg mite and northern fowl mite. Ivermectin pour-on / drops is applied to the skin. Unlicensed for use in poultry so should only be purchased and used at the advice of your vet.Ivermectin does not kill tapeworms.
you need to check this out for yourself though
levamisole (prohibit) and febendazole (safeguard) have decent efficiacy
valbazen - used off label - is the most effective tape worm medication.
round worms are most common and ivermectin is great for them as well as lice. round worms will become resistant to it if not rotated.
My Ivermectin equine paste lists treating for the following parasites: Large Strongyles (adults), Small Strongyles(adults and 4th stage larvae), Ascarids (adults and 3rd and 4th stage larvae), Pinworms (adults and 4th stage larvae), Large-mouth Stomach Worms (adults), Bots (oral and gastric stages), Lungworms (adults and 4th stage larvae), Intestinal Threadworms (adults), Summer Sores caused by Hybronema and Draschia spp. cutaneous 3d sage larvae, Dermatitis caused by neck threadworm microfilariae, Onchoceerca sp. Under each parasite is listed several scientific names for the worms that fall under each parasite category that I did not list here or it would take too much room.
Whatever the scientific name of Tapeworms is (it seems to have several names depending on the animal/human who contracted it) it seems to have to be diagnosed by a vet and treated differently from other worms. However on a good note poultry are not usually infected with tapeworms according to the research I managed to find.
On another note, I too, previously read that wormers should be rotated. I've used Ivermectin almost 3 years along with Poultry Protector and have been worm-free according to lab results so far. Going to discuss with my next vet visit about what alternative if necessary to rotate with Ivermectin. It's hard to imagine that rotating would make any difference as don't wormers have the same ingredients to be effective? Flubenvet is a wormer used in feed that will kill Gapeworm but it is a U.K. product. Will have to find a rotation product through the vet. Ivermectin is so easy to use because it is exact dosage per bird but with the waterer/feeder method some of my chickens eat/drink a lot and others not so much so it's guesswork how much each chicken has ingested to be effective. I hate guesswork but will do whatever necessary to keep a healthy flock.
As I've said before on other posts there is no end to learning about chickens and so many decisions about what works best for our situation!