Euthyrox 0.075mg (75mcg) Tablets
WARNING: Do not use this drug for weight loss. Severe and sometimes deadly side effects may happen with this drug if it is taken in large doses or with other drugs for weight loss. If you have questions, talk with the doctor. @ COMMON USES: It is used to add thyroid hormone to the body.It is used to manage thyroid cancer.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Thyroid hormone replacement
Pharmacologic Class
Thyroid hormones
Pregnancy Category
Category A
FDA Approved
Jan 1965
DEA Schedule
Not Controlled
Overview
What is this medicine?
Levothyroxine is a medicine that replaces a hormone normally made by your thyroid gland. It's used when your thyroid gland doesn't make enough of this hormone (a condition called hypothyroidism). Taking this medicine helps your body's metabolism work properly, which can improve symptoms like tiredness, weight gain, and feeling cold.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your dose on an empty stomach, at least 30 to 60 minutes before breakfast.
Important Administration Instructions
Some brands of this medication may cause choking, gagging, or trouble swallowing. If you are taking one of these products, be sure to take it with a full glass of water. Check with your pharmacist to see if this applies to your specific medication.
If you need to, you can crush your tablet and mix it with 1 or 2 teaspoons (5 or 10 mL) of water. Take your dose immediately after mixing, and do not store the mixture for future use.
Interactions with Other Substances
Do not take iron products, antacids containing aluminum or magnesium, or calcium carbonate within 4 hours before or 4 hours after taking this medication. If you are taking other medications, they may need to be taken at a different time. Consult your doctor or pharmacist for guidance on the best schedule.
Some foods, such as soybean flour (found in infant formula), may affect how this medication works in your body. Discuss this with your doctor. Additionally, if you regularly consume grapefruit juice or eat grapefruit, talk to your doctor about potential interactions.
Brand and Form Consistency
There are various brands and forms of this medication. Do not switch between different brands or forms without consulting your doctor.
Continuing Your Medication
Continue taking your medication as directed by your doctor or healthcare provider, even if you are feeling well.
Storage and Disposal
Store your medication at room temperature in a dry place, away from heat and light. Do not store it in a bathroom. If your medication comes in a blister pack, do not remove it from the pack until you are ready to take it. Do not store the removed medication for future use.
Missed Doses
If you miss a dose, take it as soon as you remember. If it is close to the time for your next dose, skip the missed dose and return to your regular schedule. Do not take two doses at the same time or take extra doses.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your dose on an empty stomach, at least 30 to 60 minutes before breakfast.
Important Administration Instructions
Some brands of this medication may cause choking, gagging, or trouble swallowing. If you are taking one of these products, be sure to take it with a full glass of water. Check with your pharmacist to see if this applies to your specific medication.
If you need to, you can crush your tablet and mix it with 1 or 2 teaspoons (5 or 10 mL) of water. Take your dose immediately after mixing, and do not store the mixture for future use.
Interactions with Other Substances
Do not take iron products, antacids containing aluminum or magnesium, or calcium carbonate within 4 hours before or 4 hours after taking this medication. If you are taking other medications, they may need to be taken at a different time. Consult your doctor or pharmacist for guidance on the best schedule.
Some foods, such as soybean flour (found in infant formula), may affect how this medication works in your body. Discuss this with your doctor. Additionally, if you regularly consume grapefruit juice or eat grapefruit, talk to your doctor about potential interactions.
Brand and Form Consistency
There are various brands and forms of this medication. Do not switch between different brands or forms without consulting your doctor.
Continuing Your Medication
Continue taking your medication as directed by your doctor or healthcare provider, even if you are feeling well.
Storage and Disposal
Store your medication at room temperature in a dry place, away from heat and light. Do not store it in a bathroom. If your medication comes in a blister pack, do not remove it from the pack until you are ready to take it. Do not store the removed medication for future use.
Missed Doses
If you miss a dose, take it as soon as you remember. If it is close to the time for your next dose, skip the missed dose and return to your regular schedule. Do not take two doses at the same time or take extra doses.
Lifestyle & Tips
- Take your medicine exactly as prescribed, usually once a day in the morning.
- Take it on an empty stomach, at least 30-60 minutes before breakfast or any other food, beverages (other than water), or medications.
- Avoid taking calcium, iron, antacids, or fiber supplements within 4 hours of your levothyroxine dose, as they can interfere with absorption.
- Do not switch between different brands of levothyroxine without consulting your doctor, as formulations can vary and may require dose adjustment.
- Inform your doctor about all other medications, supplements, and herbal products you are taking.
- Regular blood tests (TSH) are essential to ensure you are on the correct dose.
Available Forms & Alternatives
Available Strengths:
- Euthyrox 100mcg Tablets
- Euthyrox 0.125mg (125mcg) Tablets
- Euthyrox 88mcg Tablets
- Euthyrox 0.05mg (50mcg) Tablets
- Euthyrox 0.075mg (75mcg) Tablets
- Euthyrox 0.137mg (137mcg) Tab
- Euthyrox 0.175mg (175mcg) Tabs
- Euthyrox 0.150mg (150mcg) Tab
- Euthyrox 0.025mg (25mcg) Tab
- Euthyrox 0.112mg (112mcg) Tablets
- Euthyrox 0.2mg (200mcg) Tab
- Euthyrox 0.075mg (75mcg) Tablets
- Euthyrox 0.088mg (88mcg) Tablets
- Euthyrox 0.100mg (100mcg) Tablets
Dosing & Administration
Adult Dosing
Standard Dose:
Initial dose typically 1.6 mcg/kg/day orally once daily for primary hypothyroidism. Euthyrox 0.075mg (75mcg) is a common maintenance dose.
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
cardiacDisease:
Initial dose 12.5-25 mcg/day, titrate slowly.
elderly:
Initial dose 12.5-25 mcg/day, titrate slowly.
subclinicalHypothyroidism:
Typically 25-75 mcg/day, individualized based on TSH.
Pediatric Dosing
Neonatal:
10-15 mcg/kg/day orally once daily (for congenital hypothyroidism).
Infant:
6-8 mcg/kg/day orally once daily (for 6-12 months).
Child:
4-6 mcg/kg/day orally once daily (for 1-5 years); 3-5 mcg/kg/day (for 6-12 years).
Adolescent:
2-3 mcg/kg/day orally once daily (for >12 years or during puberty); full adult dose (1.6 mcg/kg/day) may be required when growth is complete.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Dialysis:
No specific adjustment needed, as levothyroxine is highly protein-bound and not significantly dialyzable.
Hepatic Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed, but monitor TSH/T4 closely as hepatic metabolism may be altered in severe cases.
Pharmacology
Mechanism of Action
Levothyroxine (T4) is a synthetic form of the natural thyroid hormone, thyroxine. It is converted to its active metabolite, liothyronine (T3), in peripheral tissues. T3 and T4 act on thyroid hormone receptors in the cell nucleus, regulating gene expression and controlling numerous metabolic processes, including protein synthesis, carbohydrate and lipid metabolism, and cellular respiration. It is essential for normal growth, development, and metabolism.
Pharmacokinetics
Absorption:
Bioavailability:
48-80% (average 60-80%), highly variable among individuals and affected by food/other medications.
Tmax:
2-4 hours (for T4); 24-48 hours (for T3 conversion and peak effect).
FoodEffect:
Decreased absorption when taken with food, especially fiber, calcium, iron, and soy products. Should be taken on an empty stomach.
Distribution:
Vd:
10-13 L (low volume due to high protein binding).
ProteinBinding:
>99% (primarily to thyroxine-binding globulin (TBG), transthyretin, and albumin).
CnssPenetration:
Limited (T4 crosses BBB poorly, T3 crosses more readily).
Elimination:
HalfLife:
Approximately 7 days (range 6-10 days); shorter in hyperthyroidism, longer in hypothyroidism.
Clearance:
Approximately 0.05 L/hr/kg.
ExcretionRoute:
Primarily renal (conjugated metabolites); small amount excreted in feces via biliary excretion.
Unchanged:
<1% (of T4 is excreted unchanged).
Pharmacodynamics
OnsetOfAction:
Gradual, typically 3-5 days.
PeakEffect:
Clinical effects typically seen within 3-4 weeks, with full therapeutic effect often taking 4-6 weeks.
DurationOfAction:
Due to long half-life, effects persist for several days after discontinuation.
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Chest pain or pressure
Fast or abnormal heartbeat
Shortness of breath
Sudden weight gain or swelling in the arms or legs
Headache
Feeling tired or weak
Changes in appetite
Unintentional weight changes
Diarrhea, stomach cramps, or vomiting
Mood changes, such as irritability, nervousness, excitability, anxiety, or other emotional changes
Shakiness
Trouble sleeping
Sensitivity to heat
Excessive sweating
Fever
Muscle cramps
Muscle weakness
Flushing
Bone pain
Changes in menstrual periods
In children: hip or knee pain, or a limp
In infants: changes in the shape of the head and face
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If you are bothered by any of the following side effects or if they do not go away, contact your doctor:
* Hair loss (usually temporary and resolves on its own within the first few months of treatment)
This is not a comprehensive list of all possible side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Chest pain or pressure
Fast or abnormal heartbeat
Shortness of breath
Sudden weight gain or swelling in the arms or legs
Headache
Feeling tired or weak
Changes in appetite
Unintentional weight changes
Diarrhea, stomach cramps, or vomiting
Mood changes, such as irritability, nervousness, excitability, anxiety, or other emotional changes
Shakiness
Trouble sleeping
Sensitivity to heat
Excessive sweating
Fever
Muscle cramps
Muscle weakness
Flushing
Bone pain
Changes in menstrual periods
In children: hip or knee pain, or a limp
In infants: changes in the shape of the head and face
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If you are bothered by any of the following side effects or if they do not go away, contact your doctor:
* Hair loss (usually temporary and resolves on its own within the first few months of treatment)
This is not a comprehensive list of all possible side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Symptoms of too much thyroid hormone (hyperthyroidism): rapid heart rate, palpitations, chest pain, nervousness, irritability, sweating, heat intolerance, unexplained weight loss, diarrhea, tremor, insomnia.
- Symptoms of too little thyroid hormone (hypothyroidism) despite treatment: persistent fatigue, weight gain, constipation, dry skin, hair loss, feeling cold, depression, muscle aches.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ An overactive thyroid gland
+ A weak adrenal gland
+ Difficulty swallowing
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor.
To ensure your safety, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your health problems
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm it is safe to do so.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ An overactive thyroid gland
+ A weak adrenal gland
+ Difficulty swallowing
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor.
To ensure your safety, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your health problems
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm it is safe to do so.
Precautions & Cautions
Important Information for All Patients Taking This Medication
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. To ensure continuous treatment, do not allow your supply of this medication to run out. You may not experience the full effects of this medication for several weeks.
If you have diabetes (high blood sugar), consult with your doctor, as this medication may affect your blood sugar control. Your doctor may need to adjust your diabetes medications. Monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as advised.
When taking biotin or products containing biotin, stop using them at least 2 days before having your thyroid levels checked to ensure accurate test results.
Potential Risks and Side Effects
High doses of this medication may increase the risk of developing weak bones (osteoporosis), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk.
This medication may also affect fertility, potentially leading to difficulties in getting pregnant or fathering a child. If you plan to conceive, consult with your doctor before starting treatment.
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy, Breastfeeding, and Pediatric Use
If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor to discuss the benefits and risks of this medication to you and your baby.
For children taking this medication, monitor their weight changes and consult with your doctor, as the dosage may need to be adjusted. Never give your child more than the prescribed dose, as this can increase the risk of severe side effects. In some cases, this medication may affect growth in children and teenagers, and regular growth checks may be necessary. Consult with your doctor to discuss any concerns.
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. To ensure continuous treatment, do not allow your supply of this medication to run out. You may not experience the full effects of this medication for several weeks.
If you have diabetes (high blood sugar), consult with your doctor, as this medication may affect your blood sugar control. Your doctor may need to adjust your diabetes medications. Monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as advised.
When taking biotin or products containing biotin, stop using them at least 2 days before having your thyroid levels checked to ensure accurate test results.
Potential Risks and Side Effects
High doses of this medication may increase the risk of developing weak bones (osteoporosis), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk.
This medication may also affect fertility, potentially leading to difficulties in getting pregnant or fathering a child. If you plan to conceive, consult with your doctor before starting treatment.
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy, Breastfeeding, and Pediatric Use
If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor to discuss the benefits and risks of this medication to you and your baby.
For children taking this medication, monitor their weight changes and consult with your doctor, as the dosage may need to be adjusted. Never give your child more than the prescribed dose, as this can increase the risk of severe side effects. In some cases, this medication may affect growth in children and teenagers, and regular growth checks may be necessary. Consult with your doctor to discuss any concerns.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia (rapid heart rate)
- Arrhythmias (irregular heart rhythm)
- Chest pain (angina)
- Tremor
- Nervousness
- Irritability
- Insomnia
- Diarrhea
- Weight loss
- Fever
- Heat intolerance
- Seizures (rare)
- Coma (rare)
What to Do:
Seek immediate medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222.
Drug Interactions
Major Interactions
- Amiodarone (can cause hypo- or hyperthyroidism, alters T4 to T3 conversion)
- Orlistat (can reduce levothyroxine absorption)
- Tyrosine kinase inhibitors (e.g., imatinib, sunitinib, sorafenib - can increase TSH and require dose adjustment)
- Proton pump inhibitors (e.g., omeprazole, lansoprazole - can decrease levothyroxine absorption)
- Sucralfate (forms insoluble complex, reduces absorption)
- Cholestyramine, Colestipol (binds levothyroxine in GI tract)
- Sevelamer (binds levothyroxine in GI tract)
- Calcium carbonate, Ferrous sulfate (binds levothyroxine in GI tract)
- Soy products (can decrease absorption)
Moderate Interactions
- Antacids (aluminum, magnesium hydroxide - reduce absorption)
- Rifampin (increases levothyroxine metabolism)
- Phenytoin, Carbamazepine, Phenobarbital (induce hepatic metabolism of thyroid hormones)
- Estrogens (increase TBG, potentially increasing levothyroxine requirements)
- Androgens (decrease TBG, potentially decreasing levothyroxine requirements)
- Beta-blockers (e.g., propranolol - may inhibit T4 to T3 conversion)
- Corticosteroids (may inhibit T4 to T3 conversion)
- Warfarin (levothyroxine may enhance anticoagulant effect, requiring lower warfarin dose)
- Digoxin (levothyroxine may decrease digoxin levels, requiring higher digoxin dose)
Minor Interactions
- Dietary fiber (may slightly decrease absorption)
- Coffee (may slightly decrease absorption if taken concurrently)
Monitoring
Baseline Monitoring
TSH (Thyroid Stimulating Hormone)
Rationale: Primary diagnostic marker for hypothyroidism and to guide initial dosing.
Timing: Prior to initiation of therapy.
Free T4 (Free Thyroxine)
Rationale: To assess baseline thyroid hormone levels and confirm diagnosis.
Timing: Prior to initiation of therapy.
Clinical symptoms of hypothyroidism
Rationale: To establish baseline symptom severity for monitoring treatment response.
Timing: Prior to initiation of therapy.
Routine Monitoring
TSH (Thyroid Stimulating Hormone)
Frequency: Every 4-6 weeks after initiation or dose change, then every 6-12 months once stable.
Target: 0.4-4.0 mIU/L (individualized based on patient age, comorbidities, and specific condition, e.g., TSH suppression for thyroid cancer).
Action Threshold: If TSH is outside target range, adjust levothyroxine dose by 12.5-25 mcg/day.
Free T4 (Free Thyroxine)
Frequency: May be checked if TSH is discordant with clinical picture, or in central hypothyroidism.
Target: 0.8-1.8 ng/dL (or laboratory specific reference range).
Action Threshold: If TSH is normal but Free T4 is low, consider malabsorption or non-compliance. If TSH is suppressed and Free T4 is high, consider overtreatment.
Clinical symptoms of hypo/hyperthyroidism
Frequency: At every follow-up visit.
Target: Resolution of hypothyroid symptoms without development of hyperthyroid symptoms.
Action Threshold: Persistent hypothyroid symptoms (fatigue, weight gain, constipation) or new hyperthyroid symptoms (palpitations, anxiety, weight loss) warrant TSH/T4 re-evaluation and dose adjustment.
Symptom Monitoring
- Fatigue
- Weight changes (gain or loss)
- Constipation
- Dry skin
- Hair loss
- Cold intolerance
- Bradycardia
- Depression
- Memory impairment
- Muscle aches
- Palpitations
- Anxiety
- Tremor
- Heat intolerance
- Diarrhea
- Insomnia
- Nervousness
- Irritability
Special Patient Groups
Pregnancy
Levothyroxine requirements typically increase during pregnancy. It is crucial to maintain euthyroidism to support fetal neurological development. Category A: Studies in pregnant women have not shown an increased risk of fetal abnormalities.
Trimester-Specific Risks:
First Trimester:
Increased levothyroxine dose often needed (by 25-50%) to maintain TSH within target range (typically <2.5 mIU/L). Untreated maternal hypothyroidism in early pregnancy is associated with adverse neurodevelopmental outcomes in the child.
Second Trimester:
Continued monitoring and dose adjustment as needed. TSH target typically <3.0 mIU/L.
Third Trimester:
Continued monitoring and dose adjustment as needed. TSH target typically <3.0 mIU/L. Postpartum, dose usually returns to pre-pregnancy levels.
Lactation
Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, which are not considered clinically significant to the infant.
Infant Risk:
L1 (Safest) - No adverse effects on the infant are expected.
Pediatric Use
Dosing is weight-based and higher per kg than in adults, especially in neonates and infants, due to rapid growth and development. Regular monitoring of TSH and Free T4 is critical to ensure proper neurological and physical development. Under-treatment can lead to irreversible cognitive impairment.
Geriatric Use
Lower initial doses (12.5-25 mcg/day) are recommended, especially in patients with underlying cardiovascular disease, due to increased sensitivity to thyroid hormones and potential for cardiac adverse effects. Dose titration should be slower and more cautious. Monitor for signs of hyperthyroidism.
Clinical Information
Clinical Pearls
- Always take levothyroxine on an empty stomach, 30-60 minutes before food or other medications, to maximize absorption.
- Consistency is key: take it at the same time every day.
- Do not crush or chew tablets unless specifically instructed (e.g., for infants, dissolve in a small amount of water).
- Patients should be advised to report any symptoms of hyperthyroidism (e.g., palpitations, anxiety, weight loss) or persistent hypothyroidism (e.g., fatigue, weight gain).
- Many medications and supplements can interfere with levothyroxine absorption or metabolism; a thorough medication review is essential.
- TSH is the primary monitoring parameter for dose adjustment in primary hypothyroidism. Free T4 may be useful in central hypothyroidism or when TSH is discordant with clinical picture.
- Full therapeutic effect and TSH stabilization may take 4-6 weeks after a dose change, so re-evaluation should not be done sooner than this.
Alternative Therapies
- No direct therapeutic alternatives for thyroid hormone replacement in hypothyroidism; levothyroxine is the standard of care.
Cost & Coverage
Average Cost:
$15 - $50 per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (generic), Tier 2 or 3 (brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.