It's fairly simple and has no health risks
In order to get rid of fleas from your house, you should get a box or two of pure borax (Boraxo for one example).
If you have carpets, spread the borax on every portion of the exposed carpets, putting a little extra in all corners and areas where light seldom shines.
If you have no carpets, cover the edges of the floor and corners with borax.
Leave the borax there for a minimum of 24 hours. 36 hours is even better. The borax desiccates both the fleas and the eggs. It breaks the life cycle of the fleas so you will not have a re-infestation. While you're waiting, wash as many clothes as you can, even the clean ones .You will want to wash all rugs and pet beds too after treating them with the borax.
After the waiting period, simply vacuum the floor very thoroughly.
You can rub the borax into your animal's fur and let it sit for an hour or so, but you will want to keep an eye on them to make sure there's not a lot of grooming. Also, check with your vet before using this method directly on the pet. The carpet, rugs and pet beds are not a problem.
Make sure you get a new flea collar for your animals at this time too.
If you want to keep fleas away, get some cedar chips or boards for your dresser drawers and pet sleeping areas. Fleas hate cedar and "flee" from it. Sorry. I think it's a legal requirement to use that joke here.
This is a method I have successfully used for years. It always works. Just make sure that you can treat the whole carpet and all other necessary areas at the same time.
I'm going to use it again shortly, as soon as I can get all the junk put away from our last visit to the in-laws.
All the best!