Common Flea and Tick Medicine Side Effects

Flea and tick medicine can be used to prevent infestations of either or both fleas or ticks or can be used to eradicate either or both after an infestation has occurred. Unfortunately, use of such medicines can produce side effects in both dogs and cats. Sometimes the symptoms can be mild and short term and therefore acceptable considering the alternative: misery and infection resulting from an unchecked infestation of ticks and/or fleas with the possibility of contracting Lyme disease. However, some side effects can produce neurological problems that must be attended to by a veterinarian.

Types of Medicines for Fleas and Ticks

There are shampoos, topicals, insecticides and flea and tick collars that can prevent the attachment of any tick to the skin of an animal. It is far better to prevent this attachment from occurring than try to treat the condition if it does occur since it is costly, time-consuming in detaching the tick and wrecks havoc and misery on the affected animal. Some collars and topicals work for 1 to 2 months and can easily be applied.

It is important to prevent a tick from attaching itself to any animal for a 48-hour period. After being attached for 48 hours, a tick will secrete fluids that can sicken the animal. The following products kill a tick and cause it to drop off before the 48-hour deadline: Frontline, Promeris Canine, Advantix, Vectra 3D, and the Preventic collar. Both Amitraz and permethrin are effective repellents, which interfere with the nervous system of the tick, paralyzing it before killing it. These repellents can effectively prevent any infestation and therefore any transmission of disease.

Side Effects from Medications for Fleas and Ticks

Some medicines produce side effects such as:

  • Rash
  • Redness
  • Loss of hair
  • Itching with discoloration
  • Drooling
  • Increased excitability
  • Changes in body temperature (lower or higher)
  • Tremors
  • Vomiting
  • Diarrhea
  • Lack of coordination
  • Seizures
  • Lethargy

If a hypersensitivity reaction occurs, consultation with a veterinarian is necessary.

Precautions When Using Flea or Tick Medications

Some medicines should not be used on cats but can be used safely on dogs and visa versa. The medication Permethrin is an example of one such drug that should not be used on cats or even on dogs that interact with cats. It is important to carefully read the directions and list of ingredients. If the animal is currently taking other medications, it is important to consult a veterinarian before administering the new medications in the cause of any drug interactions.

Other precautions are:

  • Do not use on already sick or debilitated animals.
  • Do not use on animals that interact with other animals that should not be exposed to the medication. For example, permethrin should not be used on dogs that interact with cats or that play in water, such as ponds, etc. since the substance is extremely toxic to aquatic life within the first 48 hours after application of the product.
  • Do not use in conjunction with other flea or tick control products such as flea collars.
  • Before using on pregnant or nursing animals, check with a veterinarian.
  • Before using on an animal with heart, liver or kidney disease or any other serious ailment, check with a veterinarian.
  • Monitor all reactions to any new medications within the first 48 hours for any adverse side effects.