Control and Treatment for Fleas

Fleas on dogs, cats, and other pets can be controlled and treated in multiple ways including topical treatments (e.g., flea collars, drops), systemic treatments (e.g., oral medications), and natural remedies (e.g., flea comb, boric acid). Treating the environment, or extermination, may also be needed.

Topical Flea Treatments

Fleas can be controlled in a number of different ways. Monthly insecticide medications applied as a spray or topical drops are commonly used.

Fipronil (Frontline) kills adult fleas before they have a chance to lay eggs. Applied as a spray or as topical drops, fipronil pools in the sebaceous glands and hair follicles and continues to effectively kill fleas for weeks after the initial application. Fipronil is resistant to water and has an excellent safety and efficacy (effectiveness) record.

Imidacloprid (AdvantageĀ®) kills adult fleas on contact, before they are able to lay eggs. It is applied in topical drops to the pet's back and continues to work after shampooing and swimming. Imidacloprid has an excellent safety and efficacy record.

Insecticide flea collars are available in stores and veterinary clinics.

Dips made of highly concentrated insecticide preparations may be effective at controlling fleas, but are not generally recommended because of their highly toxic nature. Many contain organophosphates, which can cause adverse reactions such as hypersalivation, lacrimation (tearing), vomiting, diarrhea, fever, muscle tremors, seizures, coma, and death. If dips are used, they should not be used more than once a week, and pet owners should follow the instructions carefully.

Pyrethrin-based flea sprays containing a natural chemical derived from chrysanthemums are safe if used properly, but they only work for about a day. Longer-lasting synthetic pyrethrin flea sprays are also available. The pet and its environment (bedding, carpet) need to be sprayed frequently and regularly to effectively control the flea population. Pyrethrin can cause adverse reactions in some pets, such as depression, hypersalivation, muscle tremors, vomiting, ataxia (muscle incoordination), dyspnea (labored breathing), and anorexia (loss of appetite).

Pyrethrin-based powder stays active on the pet's skin and fur for longer periods of time. It must be applied frequently and regularly to effectively control fleas. If the animal gets wet, the flea powder becomes inactive.

Insecticide shampoo may be helpful in some cases but has a tendency to cause excessive dryness of the skin and is not generally recommended for controlling fleas.

Systemic Flea Treatments

Lufenuron (e.g., Program) is taken in pill form or, in cats, as an injection. It works by sterilizing the fleas, preventing them from reproducing, and eventually eliminating the flea population. Because lufenuron doesn't actually kill the fleas, it should be used with an insecticide to achieve the fastest, most effective flea control. It is more effective in controlling infestations and is of little benefit in treating flea allergy dermatitis. There are several similar systemic medications in pill form or in injectable form.

Nitenpyram (Capstar) is an oral medication which begins to kill adult fleas on dogs and cats within 30 minutes of administration. It must be used in conjunction with environmental control in order to break the flea cycle. It can be used on puppies and kittens as young as 4 weeks of age. Although it has a relatively brief duration of action (a day or two), it may be repeated as often as necessary.

Natural Flea Remedies

Regularly combing the animal's coat with a flea comb is a safe, quick, and effective way to get rid of fleas. The fleas stick to the teeth of the comb and can be removed by dipping the comb into a bowl of warm, soapy water. Special attention should be paid to the pet's shoulders and neck.

Inert substances (e.g., boric acid, diatomaceous earth, silica aerogel) are very safe and effective if applied properly. They should be applied every 6 to 12 months, depending on the manufacturer's recommendation.

The decision about which flea control remedy to use can be difficult. Pet owners should discuss treatment options with their veterinarians.

Pets that have been treated with an insecticide and show signs of toxicity should be washed thoroughly to remove excess chemicals and then treated appropriately.

Treating the environment usually involves using a chemical spray or flea bomb. In some cases, professional extermination may be necessary.

Indoor fogs and sprays usually contain organophosphates or pyrethrins and can be used to treat the entire house. Using indoor fogs or sprays is less expensive than hiring a professional exterminator, and the chemicals are weaker than those a professional exterminator would use, but the procedure requires more labor. Organophosphates can cause adverse reactions such as hypersalivation, lacrimation (tearing), vomiting, diarrhea, fever, muscle tremors, seizures, coma, and death.

Professional extermination generally requires fewer applications and is sometimes guaranteed by the company. However, it can be costly, and the chemicals are highly toxic.

Publication Review By: the Editorial Staff at

Published: 28 Feb 2001

Last Modified: 15 Sep 2015