Cat flea and tick products are regulated by the Environmental Protection Agency or the Food and Drug Administration and are available through pet supply stores, catalogs, the Internet and through veterinarians. 
Cat flea and tick products come in many forms including shampoos, spot-ons, sprays, wipes, dips, collars, foggers, dusts, pills and oral medications. You will need to determine the best product for you and your cat based upon the age, health, ease of use, cost, how often you need to apply, etc.
Many of these cat flea and tick products act as repellents to keep the fleas and ticks from coming in contact with your cat. Others only act to kill adult fleas and ticks after they are already on your cat. Some products attack the immature fleas, preventing them from developing into adults. A few of the products are capable of preventing the fleas and ticks from settling on you cat and killing both adult and immature pests. Finally, some products have the advantage of preventing heartworm in cats as well.
Cats are more sensitive to organophosphate insecticides than most other animals. Organo phosphates to avoid are Permethrin, phosmet, and diazinon. It is VERY important that you do not use any flea and tick products that contain permethrin or pyrethrin, which is highly toxic to cats. Permethrin or pyrethrin will be found in flea and tick products geared to other pets including dogs, but should not be found in any cat flea and tick products. Symptoms of permethrin toxicosis are tremors, seizures, and ataxia (difficulty walking).
It is best to discuss prevention and cat flea and tick products with your veterinarian, always read the label carefully regarding your cat’s age and weight and follow application directions exactly. Serious problems can be caused by the use of cat flea and tick products on cats the product was not intended for, such as applying adult strength products on kittens. 
Also you should consult your veterinarian when using cat flea and tick products on pregnant or lactating cats, older and sick cats. Symptoms of poisoning following application can include poor appetite, depression, vomiting, diarrhea, or excessive salivation. If these symptoms do occur, wash the area applied with the cat flea and tick products with mild soap and immediately seek medical attention.
The safest cat flea and tick products on the market are prescription products that are only available from your veterinarian or by prescription from your veterinarian. If you chose an over-the-counter pet store cat flea and tick product, check with your veterinarian to determine its safety. There are times when cat flea and tick products will be pulled from the market because of safety issues, you want to make sure that you do not use these products even if already purchased and used previously. Be sure to always store cat flea and tick products away from food and from children.
