How long will flea shampoo kill fleas?

Written by Grove Collaborative

How to Treat Fleas and Ticks on Your Dog with Natural Products

Last Updated: May 6, 2022

Fleas and ticks are part and parcel when you own a dog, but don’t let 'em get you — or your dog — down. Keep reading to learn how flea and tick shampoos work and get our recs for natural alternatives to conventional flea and tick products.

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Effective flea control requires an integrated approach.

To get effective flea control, the fleas need to be targeted at each and every stage of their life-cycle. The flea life-cycle has 4 components. Adult fleas on the animal lay eggs which then fall into the environment and hatch into larvae. The larvae then develop into pupae, which ultimately emerges as an adult flea. Adult fleas live on the animal and grow by feeding on the animal's blood. This stage is the stage most people readily see. However, only about 5% of the flea population is in the adult stage. This means that up to 95% of the flea problem lies in the other unseen stages. These stages are not developing on the animal, but rather in the environment in which the animal resides.

Flea treatment therefore involves treating not only the adult fleas on the pet, but also the developing fleas (juvenile stages) in the environment.

Adult fleas on pets bite the animal, thus causing irritation and distress. The animal may be seen to scratch excessively, bite itself (particularly on the rump/tail base region), or rub its back on the ground. Owners can look for fleas by parting the fur down to skin level and searching for the moving flea. They are most commonly found around the tail base regions and can be most clearly seen running across the less furred areas of the animal (for example the groin). Alternately, the owners may see brown/black spots, known as "flea dirt" in these regions especially the tail base area. These are the flea droppings and are tell-tale signs of flea activity needing good flea control.

Many products exist for killing adult fleas on animals and the choices can seem overwhelming. The major differences between the flea control products are the effectiveness and speed of killing fleas, the convenience of flea treatment, the residual effect of the flea control product and its ability to inhibit the development of juvenile stages in the environment. It is vitally important to only use flea control products registered for use in the species of animal you are treating. Treating animals of other species with some flea control products can be harmful to the animal.

There are numerous flea control products which can be applied to the outside of the animal. These include flea control sprays, powders, shampoos and spot-on flea treatments.

Flea control powders are applied all over the animal and are used to kill adult fleas. The powder is effective as long as it is still on the animal. Hence, as the powder falls off, or is groomed off the animal, the effect reduces. Flea control powders have a very short effective life before adult fleas can again re-infest the animal.

Flea control sprays are another topical treatment which have been used extensively. The method of application involves spraying the animal all over (as per the manufacturer's recommendations). Examples include Frontline Spray. The level of tolerance an animal has for this method of application will vary widely but is generally accepted more by dogs than cats.

Flea control collars are variably effective in killing adult fleas. Some will have an effect over the entire animal, whereas others will primarily have a more localised effect around the head and neck region near the collar.

Topical "spot-ons" are a very popular flea treatment. They involve emptying a vial of flea treatment onto the skin at the back of the animal's neck. The treatments disperse in varying ways according to the product used, and then remain active in the animal's oil glands in the skin for a month. This ensures adequate protection for 4 weeks after each application. The level of tolerance by the animal and ease of application by the owner make these very popular products. There are several brands of spot-on flea treatment available. Examples of these pet meds include Frontline Plus, Nexgard, Advantage Multi (Advocate), and Revolution . All of these kill adult fleas. An added benefit of many spot-ons is their effect in preventing the further development of other stages of the flea life-cycle in the environment. For example Frontline Plus will kill fleas and prevent the development of eggs, larvae and pupae, thus dramatically impacting on the flea infestation.

The use of flea control cat or dog shampoos can be a helpful initial step in controlling adult fleas in animals that have a heavy flea burden. Washing the animal in the flea shampoo will allow the adult fleas to be quickly killed and removed from the animal by combing. However, flea pet shampoos generally do not have any residual effect. This means that adult fleas will quickly return to the animal. Therefore it is important to only use flea control shampoos as an adjunct to other flea control treatments if effective long-term flea control is to be gained. It is always recommended to check with your veterinarian about which products are safe to apply after using a flea shampoo.

Oral pet medications also exist to treat fleas. Some kill adult fleas, whereas others do not kill fleas but prevent their eggs from hatching. For example, Comfortis and Capstar are tablets which will kill adult fleas on the animal. They will have no direct effect on the other life stages. Program is a tablet or paste which is given orally to help in flea control. It does not kill fleas. The adult flea bites the treated animal and any eggs that flea lays will not hatch. Therefore it reduces the environmental burden of upcoming fleas and can help break the flea cycle. Products which kill fleas will need to be used in conjunction with this to achieve adequate flea control and relief for the animal.

As mentioned above, the majority of the flea life-cycle is in fact not spent on the animal. As fleas are prolific breeders with females laying up to 50 eggs per day, the environmental load of developing fleas can be staggering. Therefore effective flea control must address this environmental burden as well as fleas on the animal.

All pet beds and bedding should be washed regularly in hot water to kill flea larvae. The carpets and floors should be vacuumed daily to remove flea eggs, larvae and pupae. It is recommended that a flea collar be placed inside the vacuum cleaner bag to help kill any flea stages which are vacuumed up. The vacuum bag should be regularly emptied to prevent the fleas developing inside it and then being released back into the environment. It is important to vacuum lounges and other soft furnishings at the same time. The furniture should be moved regularly to allow vacuuming under chairs etc.

Flea control products known as "flea bombs", or foggers, can be purchased to help kill fleas and other life stages in enclosed areas such as the house. Each product will state whether it kills only adult fleas or other stages as well. The "flea bombs" disperse a mist into the area and the manufacturer's instructions must be followed carefully. All animals, uncovered food products and people should be removed from the treatment area during flea treatment and for the recommended time afterwards. It is necessary to vacuum all treated areas after using a flea "bomb". The depth of penetration of flea "bombs" into carpet may not be adequate to have a strong effect on the juvenile stages housed there.

External areas can be treated with outdoor flea control sprays. Since flea larvae in the outside environment like to live in shady locations, regularly mowing lawns, weeding the garden and removing piles of sand and such can help reduce the larval burden by exposing them to sunlight which kills them. Both internal and external areas can be treated by professional exterminators.

Because the flea life-cycle is complex and the majority of the life-cycle is not spent on the animal, an integrated approach to flea control is essential if adequate results are to be achieved. Treatment of the animal for adult fleas eases the discomfort and effect on the animal and reduces the number of breeding females laying eggs into the environment. Flea treatment of the environment however is also essential to ensure that the flea life-cycle is broken and that there are no fleas waiting to develop and jump onto the animal. It is vital to treat all animals in the household together for maximum results.

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