You will want to get the liquid wormer at your local vet. Some wormers over the counter are not strong enough to kill the worms and if allowed to continue will cause your puppy to become malnourished.
Anything a veteranarian gives a puppy is always the best route. If you decide to buy one off the market, Hartz is an effective brand, so follow exact instructions.
Only your vet can give you good advice on what medication is best for your puppies. If you can't afford the expense of taking the puppies in, then I suggest just calling the vet and asking for advice. Most are quite helpful in telling you the brands they sell and the dosages for your puppies.
You should see your veterinarian to obtain a safe, effective dewormer. Not all dewormers are safe for young puppies and not all are effective in treating all types of worms.
I got Strongid T from my Vet. He let me buy a big bottle and administer it myself every 2 weeks 3 times. 4 weeks, 6 weeks, and then 8 weeks. It's pretty safe. I have so far not read any side-effect horror stories.
Puppies under 8 weeks of age shouldn't be given wormer that is meant for a dog or older puppies. Most wormers on the market today aren't meant for a puppy that young. The Vet's office has Wormers meant for puppies this small.
For six week old puppies you really should get the wormer from the vet the ones they sell on the market take alot of puppies lives what you read on the box is only what they want you to know they vet will give you tubes of wormer that is made just for the puppies.
Piperazine is labeled for puppies 6 weeks old and older and is effective. Follow the label instructions. You can find it everywhere if you look for the active ingredient on the label. Even the grocery store.
If your puppy is 6 weeks or older and is outdoors alot with other dogs and other species then Strongid T or pyrantel pamoate may be too "light duty". Strongid T is labeled for puppies 2 weeks old and may not effective on all worm species.
