Levothyroxine

1,379 adverse event reports submitted to the FDA

Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.

1,379

Total Reports

159

Deaths Reported

1150.0%

Death Rate

Active Ingredients

Levothyroxine

Administration Routes

OralUnknownOphthalmic

Species Affected

Dog 1,312

Human 44

Cat 16

Unknown 4

Horse 3

Most Affected Breeds

Retriever - Labrador 204

Retriever - Golden 129

Crossbred Canine/dog 76

Beagle 53

Boxer (German Boxer) 51

Unknown 50

Chihuahua 35

Shepherd Dog - German 27

Shih Tzu 24

Terrier - Jack Russell 22

Most Reported Reactions

Vomiting 218

Diarrhoea 158

Lethargy (see also Central nervous system depression in 'Neurological') 143

Elevated alanine aminotransferase (ALT) 103

Anorexia 101

Other abnormal test result NOS 100

Death by euthanasia 100

Lack of efficacy - NOS 96

Weight loss 96

Elevated serum alkaline phosphatase (SAP) 86

Polydipsia 85

Seizure NOS 81

Outcome Breakdown

Ongoing

487 (35.8%)

Recovered/Normal

355 (26.1%)

Outcome Unknown

345 (25.3%)

Euthanized

103 (7.6%)

Died

56 (4.1%)

Recovered with Sequela

16 (1.2%)

Source: FDA Center for Veterinary Medicine — Adverse Event Reports. Data reflects voluntary submissions and may not represent actual incidence rates.