Can Stronghold be used on toys less that 1kg at 8 weeks old?

I am not using this for my litter but my neighbour has used it on some tiny pups and I wasnt sure if its ok. He said its for 2.5kg and below no minimum weight.

Have jsut got out a pack of Puppy & Kitten stronghold and read the leaflet - it does not give a minimum weight it is safe for, just less than 2.5 kg, and not under 6 weeks, so reading this it sounds like your firend can use it OK.  However I would be very reluctant to use on such tiny pups, much prefer using a liquid wormer which can be dispenses accurately according to indiividual pups weight, and frontline spray if flee control is required.

I have a large Toy breed (contradiction in terms :) ) and only use Stronghold from 12 weeks old, the pups are suaully around 2.5 kg by then.

No, no no a thousand times no!!  :-(

Go for Frontline and Panacur suspension.  Never use Stronghold on something that weighs 1kg.   PLEASE.