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Euthyrox (Levothyroxine sodium)

Written by Stephanie Nera, RPh, PharmD · Pharmacology

Updated Jul 01, 2021

Euthyrox is the brand name of levothyroxine. This levothyroxine is a synthetic version of the body’s natural thyroid hormone. Doctors prescribe levothyroxine to correct low levels of thyroid hormones or deficiency. Low thyroid levels may be caused by iodine deficiency, underactive thyroid tissue (hypothyroidism). or a resected thyroid gland (thyroidectomy).



Uses of Euthyrox

  • Benign goiter with normal thyroid (euthyroid) function
  • Prophylaxis for relapse after thyroidectomy
  • Thyroid hormone replacement therapy
  • Suppression therapy in thyroid cancer
  • Correcting low thyroid hormone levels in hyperthyroid patients being treated with anti-thyroid medications

How should I take Euthyrox?

Read the directions on the packaging for complete information. Check the label and expiration date.

For oral dosage forms, swallow it whole without chewing, crushing, or dissolving it in liquid. Take it on an empty stomach, 30 minutes to 1 hour before meals.

For parenteral dosage forms, only a licensed healthcare professional should administer it.

How do I store Euthyrox?

This product is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store it in the bathroom or the freezer. 

There may be different brands of this drug that may have different storage needs. So, it is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush this product down the toilet or pour them into a drain unless instructed to do so. Additionally, it is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Euthyrox?

Levothyroxine should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants.

Since thyroid hormone occurs naturally in the body, it is rare to have an allergic reaction or incompatibility. However, you may not be able to take this medication if you have certain medical conditions.

Is it safe during pregnancy or breastfeeding?

Levothyroxine is the preferred treatment of hypothyroidism during pregnancy. Untreated hypothyroidism increases the risk of infertility, spontaneous abortion, stillbirth, prematurity, low birthweight, and impaired brain development. Therefore, this drug is safe to take when necessary.

It passes into breastmilk, however, it is safe and preferred over other thyroid medications.

Side effects

What side effects can occur from Euthyrox?

Generally, levothyroxine is well-tolerated when taken in the right amounts. However, high doses may increase the risk of side effects which include:

  • Allergic reactions
  • Changes in appetite
  • Changes in menstrual periods
  • Chest pain
  • Diarrhea
  • Excessive sweating
  • Fast or irregular heartbeat
  • Fever
  • Heat intolerance
  • Joint pain
  • Leg cramps
  • Mental or mood changes (e.g., anxiety, irritability, nervousness)
  • Muscle weakness
  • Seizures
  • Severe or persistent headache or fatigue
  • Shortness of breath
  • Stomach cramps
  • Tremors
  • Trouble sleeping
  • Unusual weight gain or weight loss
  • Vomiting
  • Wheezing

Not everyone experiences these side effects. Additionally, there may be other side effects not listed above. If you have any concerns about a side effect, please consult your doctor or pharmacist.


What drugs may interact with Euthyrox?

Levothyroxine may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Drugs with known interactions with levothyroxine:

  • Antacids
  • Iron supplements
  • Estrogen (e.g. hormonal contraceptives, postmenopausal hormone replacement therapy)
  • Biotin (vitamin B7)
  • Diabetes medications
  • Anticoagulants (e.g. coumarin-derivatives)
  • Antivirals
  • Phenytoin
  • Orlistat
  • Tyrosine-kinase inhibitors
  • Glucocorticoids
  • Amiodarone
  • Sertraline
  • Barbiturates

Does food or alcohol interact with Euthyrox?

Euthyrox may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects.

Soybean products (e.g. tofu, soymilk) may decrease uptake of levothyroxine in the body.

It is best to take this medication on an empty stomach for better absorption. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Euthyrox?

Euthyrox may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

To make sure levothyroxine is safe for you, inform your doctor if you have:

  • A thyroid disorder (thyrotoxicosis)
  • Heart disease, coronary artery disease, or a history of blood clots
  • Diabetes
  • Anemia
  • Osteoporosis
  • Problems with your pituitary gland
  • Food or drug allergies
  • An untreated or uncontrolled adrenal gland disorder

Symptoms of Postpartum Thyroid Issues


The information provided is not a substitute for any medical advice. Therefore, you should always consult with your doctor or pharmacist before using any medication.

What is the dose for an adult?

The dose of levothyroxine is unique to each patient. Your doctor will tell you how much you need to take each day.

Typically, levothyroxine is taken once a day at least 30 minutes before breakfast.

Normal dose range for euthyroid conditions is 75-200 mcg per day.

For thyroid substitution therapy: Initial dose: 25-50 mcg per day. Maintenance dose: 100-200 mcg per day.

Suppression therapy: 150-300 mcg per day.

What is the dose for a child?

The dose of levothyroxine is unique to each patient. Your child’s pediatrician will tell you how much you need to give each day.

Typically, levothyroxine is taken once a day at least 30 minutes before breakfast. If your child has trouble swallowing tablets, it may be crushed and mixed with a liquid.

For neonates and infants with congenital hypothyroidism, the initial recommended dosage is 10 to 15 mcg per kg of body weight per day for the first 3 months.

Thereafter, the dose should be adjusted individually according to the clinical findings and thyroid hormone and TSH values.

How is Euthyrox available?

Euthyrox is available in the following dosage forms and strengths:

  • Oral tablets: 25 mcg, 50 mcg, 100 mcg, 150 mcg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to the nearest emergency room.

What should I do if I miss a dose?

If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.


Hello Health Group does not provide medical advice, diagnosis or treatment.

Written by

Stephanie Nera, RPh, PharmD


Updated Jul 01, 2021

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