The Side Effects of Soloxine for Dogs

When prescribed with the growth-stimulating drug Soloxine, dogs rarely develop side effects at all. Soloxine is a safe and effective drug, FDA approved for use in dogs.

What Is Soloxine?

Soloxine is a synthetic hormonal drug designed to stimulate growth and development, as well as boost the metabolism. It mimics thyroxine, a naturally occurring hormone that normally controls these things from the thyroid. Sometimes, however, the thyroid can't properly function and is unable to produce it. This condition is known as hypothyroidism. Without a supplement, a dog with hypothyroidism cannot grow naturally and requires medication to develop.

With hypothyroidism, a medication such as Soloxine will likely be needed for the pet's entire life.

Side Effects

When used properly, Soloxine has little to no side effects. Some dogs are allergic to Soloxine, and if a reaction occurs, cease use immediately and call your veterinarian.

Improper use, overdose and prolonged treatment may produce side effects in some dogs, and some dogs may develop minor side effects. However, medical attention should be sought if your dog exhibits:

  • Sleeping problems
  • Drowsiness
  • Decreased appetite
  • Nausea
  • Vomiting
  • Diarrhea
  • Dry mouth and coughing
  • Rash
  • Personality changes
  • Fever
  • Dizziness
  • Weight gain or loss

Other side effects may occur, and all unusual behavior should be noted and mentioned to your veterinarian.


Symptoms of overdose include the development of several conditions such as:

  • Thyrotoxicosis
  • Heat sensitivity
  • Hyperactivity

An overdose in Soloxine may also lead to further conditions such as polyuria or polyphagia.

Other Considerations

Most side effects occur when a dog overdoses, or is medicated beyond what the veterinarian has prescribed. Always give Soloxine exactly as your veterinarian has prescribed, and never give larger amounts or medicate for a longer period.

Dogs that are allergic to Soloxine (levothyroxine sodium) should not take it. It is also not recommended for dogs with Addison's Disease, or an adrenal insufficiency. Use caution and watch for side effects in dogs with high blood pressure.

Soloxine should never be used in a pet that has experienced thyrotoxicosis.

Soloxine may interact with theophylline, warfarin, barbiturates, digoxin and phenytoin, so care should be taken to ensure there is no unusual fall out from these two drugs combining. In addition to these drugs, Soloxine will react with iron or calcium, so it is advised that if your pet is also taking supplements containing them, you should not give them within four hours after having administered a Soloxine medication.

Soloxine should be given on an empty stomach, and your pet kept well hydrated.

As side effects are rare, any that appear in your pet should be brought to the attention of your veterinarian to ensure that a more serious problem has not arisen from the use of Soloxine with your dog.