Euthyrox: Uses, Side Effects and Dosage

What is EUTHYROX used for?

EUTHYROX is used to:

• treat hypothyroidism. This condition happens when the thyroid gland does not produce enough of the hormone thyroxine.
• treat certain types of thyroid cancer. For these patients, EUTHYROX is given in combination with surgery and radioactive iodine therapy.

How does EUTHYROX work?

EUTHYROX contains levothyroxine sodium, which is a man-made type of thyroxine. Thyroxine is the hormone that is normally produced by the thyroid gland.

In hypothyroidism, the thyroid gland does not produce normal amounts of thyroxine. This causes levels of thyroid hormones in the blood to drop, which can cause changes in metabolism and the proper function of many organs. EUTHYROX helps to replace or supplement thyroxine in the body.

It may take a few weeks for EUTHYROX to begin working. Until it begins working, you may not notice any change in your symptoms.

Thyroid hormone replacement therapy is usually taken for life.

What are the ingredients in EUTHYROX?

Medicinal ingredients: Levothyroxine sodium

Non-medicinal ingredients: Corn starch, croscarmellose sodium, gelatin, lactose monohydrate and magnesium stearate. The following are the colour additives by tablet strength:

Serious Warnings and Precautions

Thyroid hormones, including EUTHYROX, either alone or with other medicines, should not be used to treat obesity or for weight loss. Larger doses may cause serious or life-threatening side effects especially when taken together with medications used for weight loss.

EUTHYROX comes in the following dosage forms:

Tablets: 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg and 300 mcg.

Do not use EUTHYROX if:

• you are allergic to levothyroxine sodium or to any of the other ingredients in EUTHYROX
• you have uncorrected adrenal insufficiency. This is a condition where your adrenal glands do not make enough of the hormone cortisol.
• you have pituitary insufficiency that has not been treated. This is a condition where the pituitary gland does not make enough of some hormones.
• you have thyrotoxicosis. This is a disease where the thyroid gland is overactive and produces too much thyroxine.
• you are pregnant and also using medicines to treat an overactive thyroid
• you have recently had a heart attack, or have myocarditis or pancarditis (inflammation of the heart or heart muscle)

To help avoid side effects and ensure proper use, talk to your healthcare professional before you take EUTHYROX. Talk about any health conditions or problems you may have, including if you:

• are pregnant or plan to become pregnant. This is because your dose will likely need to be increased.
• have any heart problems, whether or not you have received treatment for them. This includes a history of damage or diseased blood vessels of the heart (coronary artery disease and coronary insufficiency), heart failure, angina, hardening of the arteries or irregular heart rate.

• have other medical problems, whether or not you have received treatment for them, including:

  • high blood pressure
  • osteoporosis
  • blood clotting disorders
  • a history of thyroid, adrenal, or pituitary gland problems
• are a woman on long-term EUTHYROX therapy, especially post-menopausal women. This is because you may experience a decrease in bone mineral density.

• have one of the following rare hereditary conditions:

  • Galactose intolerance
  • Lapp lactase deficiency
  • Glucose-galactose malabsorption

This is because EUTHRYOX contains lactose.

• have a condition where your small intestine does not absorb enough nutrients from the food you eat. This is called a malabsorption syndrome.
• have signs or symptoms of psychotic disorders
• are switching from a different brand of levothyroxine sodium
• have myxedema coma, a medical emergency, which is a type of severe hypothyroidism

Other warnings you should know about:

Oral blood thinners: Taking EUTHYROX can affect how blood thinners work. If you are taking blood thinners by mouth (oral anticoagulant drugs) such as warfarin, the dose of these may need to be changed once you start taking EUTHYROX. Your healthcare professional will do blood tests from time to time to check how quickly your blood clots.

Diabetes: If you are receiving treatment for diabetes, the dose of your diabetes medication may need to be changed after starting EUTHYROX. Monitor sugar levels in your blood and urine as directed by your healthcare professional. Report any changes to your healthcare professional right away.

Adrenal insufficiency: If you have adrenal insufficiency you may be given other medications before you start EUTHYROX.

Surgery: Tell your healthcare professional about any surgery (including dental surgery) you are planning. Before the surgery, tell your dentist or surgeon that you are taking EUTHYROX.

Premature babies with very low birth weight: Blood pressure may be monitored

regularly when levothyroxine treatment is started. This is because levothyroxine can cause a fast drop in blood pressure (known as circulatory collapse).

Breast-feeding: Small amounts of thyroid hormones will pass into your breast milk. Regardless, you can continue to take EUTHYROX while you are breast-feeding. In fact, you should not stop your treatment, as normal levels of thyroid hormones will help maintain milk production.

Monitoring and blood tests: Taking a biotin supplement may affect blood tests done to check thyroid hormone levels (called thyroid function tests). Tell your healthcare professional if you are taking biotin. It may lead to false test results. Your healthcare professional may ask you to stop taking biotin for at least 2 days before you have a thyroid function test.

Driving and using machines: If EUTHYROX is used as directed, it is not expected to affect your ability to drive or use machines. Regardless, before performing such tasks, wait until you know how you respond to EUTHYROX.

Tests and check-ups:

• Before you start taking EUTHYROX your healthcare professional will check you for other conditions. This is to make sure that EUTHYROX is right for you.

• During your treatment you will need to have regular blood tests. These will be done to make sure you are receiving the correct dose. Based on the results of these blood tests, your dose of EUTHYROX may be changed.

  Adults: These tests may be done more often at the start of your treatment (about every 6 to 8 weeks). Eventually, you may only need these blood tests every 6 to 12 months. At a minimum, your healthcare professional should check your blood and do a physical exam once per year.

  Pregnant women: These tests will be done about every 4 weeks for the first half of your pregnancy and then at least once per week between weeks 26 and 32. You will also need a blood test about 6 weeks after your baby is born.

  Children:

  • These tests will be repeated regularly:

    • at 2 and 4 weeks after the start of treatment
    • every 1 to 2 months during the first year of life
    • every 2 to 3 months between 1 and 3 years of age
    • every 3 to 12 months until the child stops growing
  • Blood tests and a physical exam should be done 2 weeks after any change in dose happens.
  • More frequent blood testing and check-ups may be needed depending on the child. Physical exams will also be done from time to time. These will include an assessment of how the child is growing.
  • To find out whether your child has permanent hypothyroidism, their dose may be lowered or their treatment stopped for about 30 days. This will happen when they are 3 years of age. Blood tests will be done during this time. Their treatment may or may not be restarted.

Tell your healthcare professional about all the medicines you take, including any drugs, vitamins, minerals, natural supplements, or alternative medicines.

The following may interact with EUTHYROX:

• Nutritional supplements such as:

  • biotin (vitamin B7, vitamin H; including for hair and nail)
  • calcium carbonate
  • ferrous sulphate
  • vitamin B3 (niacin / nicotinic acid)

• Medicines to treat heart problems including high blood pressure such as:

  • digitalis glycosides (e.g. digoxin)
  • beta blockers like metoprolol, atenolol, bisoprolol, and propranolol
  • blood thinners like warfarin and heparin
  • amiodarone
  • diuretics like furosemide
  • nitroprusside
• Medicines to treat diabetes including insulin, tolbutamide or other medicines to lower blood sugar levels

• Medicines to treat digestion problems such as:

  • antacids that contain aluminum and magnesium (e.g. aluminum and magnesium hydroxides, simethicone)
  • proton pump inhibitors
  • sucralfate
  • metoclopramide

• Medicines used to lower high cholesterol such as:

  • cholestyramine
  • colestipol
  • lovastatin

• Medicines used to treat mental health problems and seizures such as:

  • antidepressants like sertraline, amitriptyline, maprotiline, St. John’s Wort
  • phenobarbital
  • carbamazepine
  • lithium
  • diazepam
  • phenytoin
  • aminoglutethemide
  • methadone, heroin
  • hydantoins
  • perphenazine
• A medicine used to treat pain called ketamine

• Medicines to treat some cancers such as:

  • tyrosine kinase inhibitors like imatinib and sunitinib
  • octreotide
  • 5-flurouracil
  • Mitotane
  • Tamoxifen
  • Interleukin-2
  • Interferon-alpha
  • mercaptopurine
• Medicines used for weight lost including orlistat and other diet pills

• Medicines used to treat inflammatory conditions such as:

  • glucocorticoids (corticosteroids like dexamethasone and hydrocortisone)
  • non-steroidal anti-inflammatory drugs (NSAIDs) like fenamates, phenylbutazone and salicylates

• Other medicines to treat thyroid problems such as:

  • propylthiouracil (PTU)
  • methimazole
• Iodide, which is used for imaging like x-rays and CT scans
• Medicines for asthma or other breathing problems like theophylline and beta-sympatholytics / sympathomimetics (including salbutamol)

• Medicines to treat bacterial, viral or fungal infections such as:

  • medicines to treat HIV and AIDS including ritonavir, indinavir and lopinavir
  • medicines to treat tuberculosis such as para-aminosalicylate and ethionamide
  • ciprofloxacin
  • sulfonamides
  • rifampin
  • resorcinol
• A medicine to treat Parkinson’s disease and restless leg syndrome called dopamine

• Medicines to lower levels of phosphorus in the blood such as:

  • sevelamer
• A medicine used to treat trouble sleeping called chloral hydrate

• Medicines used to treat malaria including:

  • chloroquinone
  • proguanil

• Hormones such as

  • estrogens that are taken by mouth including birth control pills
  • hormone replacement therapy
  • muscle building hormones including anabolic steroids
  • growth hormones such as somatropin

Eating certain foods like soybean flour (infant formula) and other soy containing products, cotton seed meal, walnuts, and dietary fiber may decrease the absorption of levothyroxine sodium. You may require a change in your dose.

Some medicines or supplements may interfere with blood tests done to measure thyroid hormone levels (called thyroid function tests). It is important to tell your healthcare professional of all medicines or supplements you are taking before and at the time of any blood test.

How to take EUTHYROX:

• Exactly as your healthcare professional tells you.

• Take your dose once per day at the same time each day on an empty stomach.

  • Adults and children: take the dose preferably 30 minutes to 1 hour before breakfast.
  • Infants: give the dose at least 30 minutes before the infant’s first meal of the day.
• Swallow tablets whole with a glass of water.

• If your infant or child cannot swallow EUTHRYOX tablets whole, they can still take this medicine by following these steps:

  • Crush tablet(s) and mix the freshly crushed tablet(s) in about 5 to 10 mL (1 or 2 teaspoons) of water or a small amount of food like apple sauce. Do not mix the crushed tablets with foods or formula that contain large amounts of soybean, fibre, or iron.
  • Give this mixture to the child by spoon or dropper.
  • Do not store the mixture for any period of time. Prepare a new mixture each time your child or infant needs to take their dose.
• Food and drinks can affect how your body absorbs EUTHRYOX. For this reason, if you do take your dose with food or drinks, be sure to take it this way each time. You must be consistent with how you take your dose.
• If you are using other medicines, you should take your EUTHRYOX 4 hours before or 4 hours after these other medicines. Your healthcare professional can help you to establish when to take all of your medications.

Usual dose:

The usual dose of EUTHYROX will be different for everyone. Your healthcare professional will decide on the dose that is right for you. Your dose will depend on:

• your age
• your weight
• the type of thyroid condition you have
• any other illness that you have (including if you are pregnant or have heart problems)
• if you are taking certain other medications
• how long you have had symptoms of thyroid problems
• how severe your symptoms are

You are likely to start at a lower dose. Your healthcare professional will adjust your dose based on your response to the medication. A child’s dose will change as they grow and get older.

Use EUTHYROX only as prescribed by your healthcare professional. Do not change the amount you take or how often you take it, unless your healthcare professional tells you to. Like all medicines obtained from a healthcare professional, EUTHYROX must be used only by you and for the condition for which your healthcare professional has prescribed it. Do not stop taking EUTHYROX without first talking to your healthcare professional.

Overdose:

You may not experience symptoms of an overdose until several days after taking too much EUTHYROX.

Signs and symptoms of overdose may include: weight loss, increased appetite, heart palpitations (fast or irregular beating of the heart), nervousness, confusion, disorientation, diarrhea, abdominal cramps, sweating, fever, changes in period bleeding, convulsions, and seizures (fits). Blood clots in the brain, coma and death are also possible. If a large overdose occurs, additional treatment and measures from a healthcare professional will be needed.

Missed Dose:

If you miss a dose of EUTHYROX, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and continue with your usual dosing schedule. Do not take 2 doses at the same time to make up for a missed dose. If you miss 2 or more doses in a row contact your healthcare professional.

What are possible side effects from using EUTHYROX?

These are not all the possible side effects you may have when taking EUTHYROX. If you experience any side effects not listed here, tell your healthcare professional.

• fever, flushing and excessive sweating
• trouble dealing with heat
• hyperactivity, irritability, restlessness, nervousness, anxiety, rapid changes in emotions
• trouble sleeping
• fatigue
• temporary hair loss
• diarrhea, vomiting, nausea, stomach cramps
• changes in period (menstrual cycle), trouble have a child (impaired fertility)
• headache
• shortness of breath
• muscle weakness, cramps, tremors
• reduced adult height due to early closure of growth plates in the bones of children

EUTHYROX can cause abnormal test results including liver function tests. Your healthcare professional will decide when to perform blood tests and will interpret the results.

If you think you, or a person you are caring for, have taken too much EUTHYROX, contact a healthcare professional, hospital emergency department, or regional poison control centre immediately, even if there are no symptoms.

If you have a troublesome symptom or side effect that is not listed here or becomes bad enough to interfere with your daily activities, tell your healthcare professional.

Reporting Side Effects

Storage:

Store between 20°C to 25°C. Protect from light and moisture.

Keep out of reach and sight of children.

If you want more information about EUTHYROX:

• Talk to your healthcare professional
• Find the full product monograph that is prepared for healthcare professionals and includes this Patient Medication Information by visiting the Health Canada website: (https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/drug-product-database.html; the manufacturer’s website at www.emdserono.ca, or by calling 1-888-737-6668.

Last Revised OCT 21, 2024