To get rid of gnats in the house quickly, several effective methods can be used:

1. Make vinegar traps: Pour apple cider vinegar into a glass or bowl, add a few drops of dish soap, and optionally cover with plastic wrap poked with holes. Gnats are attracted to the vinegar but get trapped and drown because of the soap's surface tension reduction.
2. Use a bug zapper or an insecticidal spray designed for indoor flying insects to kill gnats on contact.
3. Pour boiling water down the drains to kill gnat eggs and larvae that breed there.
4. Set out stale beer, wine, or a piece of very ripe fruit in a container with a paper cone or plastic wrap trap to lure and trap gnats.
5. Use sticky traps with bright colors like yellow to catch adult gnats.
6. For fungus gnats in houseplants, watering plants with a solution using mosquito bits or diluted hydrogen peroxide can kill larvae in the soil.
7. Additional methods include candle traps (lighting candles in a dark room to attract and kill gnats) and regular cleaning to eliminate breeding grounds such as standing water or overripe fruit.

Combining these approaches and maintaining cleanliness is essential to get rid of gnats quickly and prevent reinfestation.