So sorry it has taken so long to get back to you all.
Took puppy (max) to the vets. He is fine. kept a really close eye on him, but he has no ill effects.
Paracetamol (which is a pain reliever here in the uK) can be dangerous for dogs. It is VERY poisonous to cats though.
luckily he only had a little bit, and it was a childrens sachet, so not very strong.
It has tought me a VERY important lesson though. You can't be too careful can you? He is into everything, and he is just too precious to take that chance.
Thanks everyone for all your help and thoughts