L-Thyroxine is a veterinary medicine for underactive thyroid in dogs and cats (primary and secondary hypothyroidism). L-Thyroxine is one of the veterinary medicines that can only be obtained from a veterinarian or from a pharmacy (UDA) on prescription from a veterinarian.
L-Thyroxine has registration number NL 9049.


  • To be used in an underactive thyroid (primary and secondary hypothyroidism).


No known contraindication.


20 micrograms levothyroxine sodium per kg body weight per day, divided into 1 – 2 times. This corresponds to 1 tablet of L-thyroxine per 10 kg of body weight, divided over 1 - 2 times. Adjust the dose based on plasma thyroxine concentrations. Administer L-thyroxine orally.


Per tablet: levothyroxine sodium 200 micrograms (thyroid hormone).

Side effects

No known side effect.


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