Synthroid vs. Euthyrox

Are Synthroid and Euthyrox the Same Thing?

Synthroid (levothyroxine sodium) and Euthyrox (levothyroxine sodium) are synthetic compounds identical to T4 (levothyroxine) produced by the human thyroid gland used to treat hypothyroidism (low thyroid hormone).

Synthroid is also used for pituitary TSH suppression.

Euthyrox is also used as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.

Side effects of Synthroid and Euthyrox that are similar include headache, nervousness, irritability, sleep problems (insomnia), heat intolerance, changes in appetite or changes in weight, and changes in menstrual periods.

Side effects of Synthroid that are different from Euthyrox include fever, hot flashes, sweating, nausea, and temporary hair loss.

Side effects of Euthyrox that are different from Synthroid include irregular heartbeats, heart attack, shortness of breath, muscle spasm, tremors, muscle weakness, diarrhea, and skin rash.

Both Synthroid and Euthyrox may interact with glucocorticoids, amiodarone, heroin/methadone, ferrous sulfate, antacids, sucralfate, clofibrate, oral contraceptives, estrogens, 5-fluorouracil, mitotane, tamoxifen, furosemide, heparin, hydantoins, nonsteroidal anti-inflammatory drugs (NSAIDs), salicylates, carbamazepine, phenobarbital, rifampin, beta-blockers, antidepressants, antidiabetics or insulin, anticoagulants, cardiac glycosides, ketamine, and sympathomimetics.

Synthroid may also interact with dopamine/dopamine agonists, octreotide, aminoglutethimide, iodide, lithium, methimazole, propylthiouracil (PTU), sulfonamides, tolbutamide, orlistat, cytokines, growth hormones, bronchodilators, radiographic agents, chloral hydrate, diazepam, ethionamide, lovastatin, metoclopramide, 6-mercaptopurine, nitroprusside, para-aminosalicylate sodium, perphenazine, resorcinol (excessive topical use), and thiazide diuretics.

Euthyrox may also interact with calcium carbonate, bile acid sequestrants, ion exchange resins, proton pump inhibitors (PPIs), androgens, steroids, asparaginase, slow-release nicotinic acid, and tyrosine-kinase inhibitors.

What Are Possible Side Effects of Synthroid?

Common side effects of Synthroid include:

  • fever,
  • hot flashes,
  • sensitivity to heat,
  • sweating,
  • headache,
  • nervousness,
  • irritability,
  • nausea,
  • sleep problems (insomnia),
  • changes in appetite or changes in weight,
  • changes in menstrual perdiods,
  • and temporary hair loss.

Notify your doctor if you experience serious side effects of Synthroid including rapid heartbeat, fluttering in your chest, or chest pain.

What Are Possible Side Effects of Euthyrox?

Common side effects of Euthyrox include:

  • irregular heartbeats,
  • heart attack,
  • shortness of breath,
  • muscle spasm,
  • headache,
  • nervousness,
  • irritability,
  • insomnia,
  • tremors,
  • muscle weakness,
  • increased appetite,
  • weight loss,
  • diarrhea,
  • heat intolerance,
  • menstrual irregularities, and
  • skin rash

What Is Synthroid?

Synthroid (levothyroxine sodium) is a synthetic compound identical to T4 (levothyroxine) produced by the human thyroid gland used to treat hypothyroidism due to many causes (for example):

  • thyroid removal,
  • thyroid atrophy,
  • functional T4 deficiency,
  • radiation treatment of the thyroid,
  • and other causes).

Synthroid is also used for pituitary TSH suppression.

What Is Euthyrox?

Euthyrox (levothyroxine sodium) is L-thyroxine (T 4) indicated in pediatric and adult patients as replacement in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism; and as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer. Euthyrox is available in generic form.

SLIDESHOW

Hyperthyroidism Symptoms and Treatment See Slideshow

What Drugs Interact With Synthroid?

Synthroid may interact with ferrous sulfate iron supplements, sucralfate, and antacids.

Synthroid may also interact with dopamine/dopamine agonists, glucocorticoids, octreotide, aminoglutethimide, amiodarone, iodide, lithium, methimazole, propylthiouracil (PTU), sulfonamides, tolbutamide, orlistat, clofibrate, oral contraceptives, estrogens, heroin/methadone, 5-fluorouracil, mitotane, tamoxifen, furosemide, heparin, hydantoins, nonsteroidal anti-inflammatory drugs (NSAIDs), salicylates, carbamazepine, phenobarbital, rifampin, beta-adrenergic antagonists, anticoagulants, antidepressants, antidiabetics, cardiac glycosides, cytokines, growth hormones, ketamine, bronchodilators, radiographic agents, sympathomimetics, chloral hydrate, diazepam, ethionamide, lovastatin, metoclopramide, 6-mercaptopurine, nitroprusside, para-aminosalicylate sodium, perphenazine, resorcinol (excessive topical use), and thiazide diuretics.

What Drugs Interact With Euthyrox?

Euthyrox may interact with calcium carbonate, ferrous sulfate, bile acid sequestrants, ion exchange resins, proton pump inhibitors (PPIs), sucralfate, antacids, clofibrate, estrogen-containing oral contraceptives, estrogens (oral), heroin/methadone, 5-fluorouracil, mitotane, tamoxifen, androgens, steroids, asparaginase, glucocorticoids, slow-release nicotinic acid, salicylates, carbamazepine, furosemide, heparin, hydantoins, nonsteroidal anti-inflammatory drugs (NSAIDs), phenobarbital, rifampin, beta blockers, amiodarone, antidiabetic drugs or insulin, anticoagulants, digitalis glycosides, antidepressants, ketamine, sympathomimetics, and tyrosine-kinase inhibitors. Tell your doctor all medications and supplements you use.

How Should Synthroid Be Taken?

Synthroid is prescribed in tablets that range from 25 to 300 mcg in strength and is usually taken once a day with a full glass of water (about 8 ounces) 30 to 60 minutes before breakfast for best adsorption into the body. Children can take the medicine if the tablet is crushed and put into about 1 to 2 teaspoons of water; do not store or delay giving this crushed pill suspension. Doctors often may have to slowly increase the dose; patients should not increase or decrease this medication themselves. Because some preparations of the drug may contain iodine or lactose, patients should tell their doctors about such allergies or reactions to these components. Many drugs can inhibit Synthroid's adsorption by the body; other medications may increase or decrease its effectiveness once it is adsorbed. Providing a complete list of medications to the doctor will help with getting the correct dose established for each individual patient. Pregnant and lactating females need to discuss the dose and use of this medication with their caregivers.

How Should Euthyrox Be Taken?

Administer a dose of Euthyrox once daily, on an empty stomach, one-half to one hour before breakfast. Administer Euthyrox at least 4 hours before or after drugs that are known to interfere with absorption.

QUESTION

Where is the thyroid gland located? See Answer
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References


AbbVie. Synthroid Product Monograph.

https://www.synthroid.com

FDA. Euthyrox Product Information

https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/021292s004,021292s005,021292s006lbl.pdf

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