Yep, I used the eSHa products to treat for worms in my guppies recently. Apparently most livebearers sold in stores that were raised in large fish farms abroad are carrying both round and flat worms. If you can't see a worm to ID it - as I couldn't, yet my fish had all the symptoms of worms- you need a treatment that will do both, or two separate treatments - one for roundworms and one for flatworms.
Different products are available in the US vs the US, I don't think you can get eSHa products there that seem to have cured my problem. API General Cure looks as though it will treat flatworms and gill flukes, but you'll need another treatment for roundworms if this doesn't work. Just be wary of buying cheap generic wormers, since a lot don't seem to have the ingredients necessary to treat a broad spectrum of worms. Better to check the active ingredient and ensure it will actually clear the problem. I'd used a general de-wormer on my guppies when I bought them, but it didn't touch whatever worm they were carrying.
Our disease expert,
@Colin_T says;
"You can use Praziquantel to treat tapeworm and gill flukes. And Levamisole to treat thread/ round worms. If you can't find these medications, look for Flubendazole, which treats both lots of worms."