Since fleas are so small and so hard to kill off, your best bet is to prevent your cat from getting fleas in the first place. Although they're not very dangerous, they're known to carry tapeworms and to make your pets very uncomfortable. Fleas do best in warm weather, but once they're in your house, they don't care about what's going on outside. Stop the invasion before it happens by regularly treating your cat and dog for fleas. Flea collars, sprays and powders aren't your best alternatives; instead, talk to your veterinarian about professional-strength treatments. These are used for prevention and for eradication; plus, they often protect against heartworm, ear mites and intestinal parasites, too.
Sometimes it's too late to prevent fleas. To confirm whether your cat already has them, check his fur for small, black, comma-shaped droppings. Also look for live fleas scurrying around. Ruffle your cat's fur on a light-colored surface to see whether any black specks fall out. Smear the specks with a wet tissue: If there's a streak of blood, you definitely have a flea problem. Regular grooming will let you catch a flea problem earlier in the game.
To get rid of fleas, talk to your veterinarian immediately. He can give you any necessary shampoos, foams, dips, sprays, topical treatments, oral meds or foggers you need. But getting rid of the bugs from your cat's fur is only half the battle. You also need to eradicate fleas from your home. Vacuum everything and get rid of the vacuum bag when you're done. Wash all linens and towels in hot water and clean up your yard. Then put everything in your house away and get all the people and pets out. Use the fogger you got from the vet to kill off any stragglers. Repeat these steps to handle any fleas that hatched after you treated the house.