Revolution(®) with active ingredient selamectin is a once-a-month topical solution for the prevention or treatment of fleas and parasites. Through its actions it is able to paralyse invading entities, at which point your dog will be able to pass them from its body naturally. Selamectin is a semi-synthetic member of the avermectin class of substances, which includes ivermectin, a drug best known as the active component of Heartgard(®). Semi-synthetic avermectins were developed to improve safety and increase the efficacy of the drug against a wider range of infections.

Revolution Or Heartgard?

Both of these medicines avermectins, but there are several key differences between the two that you should be aware of. Below we have listed both the pros and the cons of choosing Revolution over Heartgard to help you make an informed decision:


  • Considered safer
  • Effective against insects (fleas, ticks etc.)
  • Can be used in breeds with the MDR1 mutation (herding breeds are at a higher risk)


  • More expensive
  • Topical solutions can be uncomfortable
  • May not be as effective at preventing heartworm

We tend to prefer Revolution due to its safety, but would suggest Heartgard to owners when there is a serious risk of heartworm infection.

Recommended Dosage

Be sure to speak to a vet before giving Revolution to your dog.

The minimum dosage of topical selamectin suggested by the manufacturer is 2.7 mg/lb, which in most cases should be applied once a month. We recommend marking the dates on a calendar to avoid confusion. In some cases you will only be required to use the product once for effective treatment, without the need for repeated monthly administration.

Revolution products are sold in color-coded boxes made specifically for different sized dogs. Please see the table below for information on the current color-coding. Owners should also check the packaging which should always display the weight range, as companies can change their designs from time to time. Owners should always seek the approval of their vet before using this medicine.

Note: Revolution products are not suitable for puppies under 6 weeks of age, regardless of their weight.

Weight of dog (lbs)

Box to use

0 – 5Mauve box (15 mg/0.25 ml)
5.1 – 10Purple box (30 mg/0.25 ml)
10.1 – 20Brown box (60 mg/0.5 ml)
20.1 – 40Red box (120 mg/1.0 ml)
40.1 – 85Teal box (240 mg/2.0 ml)
85.1 – 130Plum box (360 mg/3.0 ml)

For a dog who weighs more than 130 pounds you will need to use an appropriate combination. For example, if you have a 150 pound dog you would need one plum-colored box and one brown box.

In cases of severe tick infestation you may be asked to use the product twice each month.

Example: If your dog weighs 25 lbs you would buy the red box and apply the entire contents of a single tube once per month.

How long will my box last?

You will usually be able to select the number of application tubes your box of Revolution contains. For example if you buy a box of 6 tubes it will typically last for 6 months, unless your pet requires twice-monthly application.

How to administer Revolution correctly:

Please follow our steps for the correct application of this medicine:


Application step 1Hold the tube upright and press down firmly on the cap to break the seal (you will hear a click). Remove the cap and check that the seal has been punctured. If the seal has been punctured proceed onto the next step.


Application step 2Part your dog’s hair at the base of their neck to reveal their skin. Place the applicator tip against the bare skin and squeeze the tube until the entire contents have been emptied. Keep pressure maintained on the final squeeze to avoid drawing product back up into the tube.


Application step 3Keep the tube squeezed and drag it up and away from the skin. Check that the tube has been emptied entirely before disposing of it in a suitable fashion.

IMPORTANT: Do not apply selamectin to a wet dog, ensure their coat is completely dry before use. Avoid bathing your dog or allowing them to get wet up to two hours following application.

How Safe Is It?

The active ingredient selamectin safe for use in most dogs and is approved by the FDA under application number 141-152. Because it does not cross the blood-brain barrier readily it is quite safe for use in herding breeds such as Collies who tend to carry the MDR1 gene mutation. Dogs with the MDR1 mutation are more susceptible to negative (even dangerous) effects following the use of standard avermectin products like Heartgard. Studies have confirmed selamectin’s safety for use in avermectin-sensitive dogs, but it’s still best to practice caution in these cases by watching your pet closely for negative side effects.

Further studies which tested for the broader safety of the drug have also been positive. Pets who accidentally swallow the substance are unlikely to experience severe reactions, though applying the medicine correctly will avoid the possibility of oral ingestion.

Pregnancy: The manufacturer states that the medicine is safe for both pregnant and lactating pets. This was confirmed through a study published on June 23, 2000, which you can find here.

Instructions For Safe Use

Before treatment make an appointment with the vet to discuss your dog’s suitability for selamectin. For treating certain conditions such as ear mite infestations you may be asked to use selamectin once without repeated administration each month. Some conditions may require more frequent dosing, up to twice a month. During the consult you should tell your vet about:

  • Other medicine your dog is taking as well as any medical conditions they suffer from
  • Prior bad reactions to avermectins such as Heartgard (ivermectin)

If your pet is very ill your vet will likely advise against treatment.

Your vet should also talk you through the process of correctly applying the liquid. Make sure to ask your vet questions if you don’t understand something.

Contraindications & Drug Interactions

Despite the safety of selamectin, there are several contraindications as well as several drugs which aren’t recommended for use in conjunction with this substance.


The manufacturer recommends that owners avoid use on ill or otherwise severely debilitated dogs, and owners should avoid applying selamectin to puppies who are less than 6 weeks old. Avermectin-sensitive breeds are likely to suffer no serious adverse effects following the use of Revolution, but caution is advised.

Drug Interactions

Administering selamectin alongside drugs which inhibit p-glycoprotein is not recommended. Administering the drug to dogs with the MDR1 gene mutation in conjunction with the following drugs is also not recommended:

Amiodarone, carvedilol, clarithromycin, cyclosporine, diltiazem, erythromycin, itraconazole, ketoconazole, quinidide, sprionolactone, tamoxifen, verapamil.

What Are The Possible Uses

Revolution is most often used for treating/preventing parasite infections or insect infestations including:

  • Fleas
  • Heartworm
  • Ticks (Dermacentor variablis only)
  • Mites
  • Mange (sarcoptic)

Though Revolution is able to prevent heartworm infection, there is not much evidence for the efficiency of the medicine against existing infections. This is due to its ineffectiveness against adult heartworms. It may be able to help infected dogs over time when use of selamectin is continued, however we would urge owners to discuss the use of ivermectin or immiticide with their vet in these cases.

Possible Side Effects

Studies have shown that adverse effects are rare, however, during treatment the following may occur:


  • Diarrhea
  • Vomiting
  • Tremors
  • Weight loss
  • Itching
  • Skin redness
  • Fatigue
  • Salivation
  • Rapid breathing

Very Rare

  • Seizures
  • Loss of co-ordination
  • Swelling

If your pet experiences any negative side effects following the use of Revolution products you should contact your vet for advice.


Overdose has been shown to rarely cause issues except in avermectin-sensitive dogs. In one study dogs given oral selamectin at a dosage of 6.8 mg/lb experienced no side effects, though one sensitive Collie experienced a loss of co-ordination. Topical overdoses also seemed to produce zero adverse effects in puppies, though avermectin-sensitive breeds experienced salivation. Despite this, if you do accidentally administer an overdose, or if you suspect your dog has gained access to the substance and ingested an overdose, you should contact the vet or the ASPCA Poison Control hotline on (888) 426-4435 immediately.