Hope you like the stink of dead rodents in your walls...
That's a problem with pretty much any of the poisons, yes.
Poison is just a band-aid, fix however they are getting into the house.
We live in an old wooden farmhouse; it's not really feasible to stop rodents from getting in altogether - just as we have a sump pump in the basement for the water that gets in, standard operating procedure here in rural Ontario. We have, however, added .2 inch steel wire mesh under the deck, to a depth of two feet, which helped.
I thought warfarin was still #1 for what it's worth... As far as I recall rodenticide has to be slow acting, else the neighbours will notice something is awry when the victim drops dead.
I didn't say the Vitamin D was fast, I said the rats eat a lethal dose at one sitting. When rats return to the nest the alpha male smells their breath, and when they start to die, the remaining rats will soon stop eating the bait. So any poison that takes more than one feeding to kill will tend not to kill all the rats, unless you only have a very few rats. But if it kills the rats too soon, they'll notice and avoid the bait. It's tricky to get right. Multiple-feed poison is OK in a city if they're coming up from the sewers or other underground tunnels, but if you have a nest in your walls, forget it.
Warfarin is #1 in sales, sure. You have to keep buying it, because it won't kill them all. In addition, a large proportion of rats are immune to warfarin these days. I didn't want to mention brand names in case it sounded like an advert, but Quintox and Terad3 are the leading Vitamin D poisons (both from Bell Labs, one newer than the other). Quintox is also the only rat poison that can be used on an organic farm here. You can also get it in liquid form, which is good if you're confident there are no other animals, children, etc ;-) - e.g. it's used at a local power station here. The rats have to drink a lot of liquid each day so they're particularly attracted to it.
Thanks for replying. And yes, you're right, we had a bad smell in the walls ;D