Euthyrox 0.112mg (112mcg) 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
Pharmacologic Class
Thyroid hormone replacement
Pregnancy Category
A
FDA Approved
Jul 1949
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, affecting energy, weight, body temperature, and more.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely.
Take your medication on an empty stomach, at least 30 to 60 minutes before breakfast.
Some brands of this medication may cause choking, gagging, or trouble swallowing. If you have one of these brands, be sure to take it with a full glass of water. Check with your pharmacist if you're unsure.
If you need to, you can crush your tablet and mix it with 1 or 2 teaspoons (5 or 10 mL) of water. Take the dose immediately after mixing, and do not store it for later use.
Important Interactions to Consider
Do not take iron products, antacids containing aluminum or magnesium, or calcium carbonate within 4 hours before or 4 hours after taking your medication.
If you take other medications, they may need to be taken at a different time than your current medication. Check with your doctor or pharmacist for guidance on the best schedule.
Certain foods, such as soybean flour (found in infant formula), may affect how your medication works. Discuss this with your doctor.
If you regularly drink grapefruit juice or eat grapefruit, talk to your doctor about potential interactions.
Using the Correct Form of Your Medication
There are different brands and forms of this medication. Do not switch between them without consulting your doctor.
Continue taking your medication as directed by your doctor or healthcare provider, even if you feel well.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, away from the bathroom.
Protect it from heat and light.
If your medication comes in a blister pack, do not remove it until you're ready to take it. Do not store the removed medication for future use.
What to Do If You Miss a Dose
Take a missed dose as soon as you remember.
If it's 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 get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely.
Take your medication on an empty stomach, at least 30 to 60 minutes before breakfast.
Some brands of this medication may cause choking, gagging, or trouble swallowing. If you have one of these brands, be sure to take it with a full glass of water. Check with your pharmacist if you're unsure.
If you need to, you can crush your tablet and mix it with 1 or 2 teaspoons (5 or 10 mL) of water. Take the dose immediately after mixing, and do not store it for later use.
Important Interactions to Consider
Do not take iron products, antacids containing aluminum or magnesium, or calcium carbonate within 4 hours before or 4 hours after taking your medication.
If you take other medications, they may need to be taken at a different time than your current medication. Check with your doctor or pharmacist for guidance on the best schedule.
Certain foods, such as soybean flour (found in infant formula), may affect how your medication works. Discuss this with your doctor.
If you regularly drink grapefruit juice or eat grapefruit, talk to your doctor about potential interactions.
Using the Correct Form of Your Medication
There are different brands and forms of this medication. Do not switch between them without consulting your doctor.
Continue taking your medication as directed by your doctor or healthcare provider, even if you feel well.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, away from the bathroom.
Protect it from heat and light.
If your medication comes in a blister pack, do not remove it until you're ready to take it. Do not store the removed medication for future use.
What to Do If You Miss a Dose
Take a missed dose as soon as you remember.
If it's 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 on an empty stomach, typically 30-60 minutes before breakfast, with a full glass of water.
- Avoid taking with food, calcium, iron supplements, antacids, or other medications that can interfere with absorption. Separate by at least 4 hours.
- Take at the same time each day for consistent absorption.
- Do not switch between different brands or generic versions without consulting your doctor, as formulations can vary slightly and affect absorption.
- Inform all healthcare providers that you are taking levothyroxine, especially before any new medications or procedures.
- Regular blood tests (TSH) are crucial to ensure 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 for primary hypothyroidism. Adjust by 12.5-25 mcg increments every 4-6 weeks based on TSH levels.
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
cardiacDisease:
Initial dose 12.5-25 mcg/day, titrate slowly.
elderly:
Initial dose 25-50 mcg/day, titrate slowly.
subclinicalHypothyroidism:
Typically 25-75 mcg/day, individualized.
Pediatric Dosing
Neonatal:
10-15 mcg/kg/day orally for congenital hypothyroidism.
Infant:
6-8 mcg/kg/day orally (3-12 months).
Child:
4-5 mcg/kg/day orally (1-5 years); 2-3 mcg/kg/day orally (6-12 years).
Adolescent:
1.6 mcg/kg/day orally or 150 mcg/day maximum (puberty and growth completion).
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed.
Moderate:
No adjustment needed.
Severe:
No adjustment needed.
Dialysis:
No adjustment needed; not significantly dialyzable.
Hepatic Impairment:
Mild:
No specific adjustment needed, but monitor TSH closely.
Moderate:
No specific adjustment needed, but monitor TSH closely.
Severe:
No specific adjustment needed, but monitor TSH closely.
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 then enters the cell nucleus and binds to thyroid hormone receptors, regulating gene expression and controlling numerous metabolic processes, including protein, fat, and carbohydrate metabolism, and influencing growth and development.
Pharmacokinetics
Absorption:
Bioavailability:
48-79% (average 70-80%)
Tmax:
2-4 hours
FoodEffect:
Decreased absorption with food, especially fiber, soy, and certain minerals (calcium, iron). Should be taken on an empty stomach.
Distribution:
Vd:
10-13 L
ProteinBinding:
>99% (primarily to thyroxine-binding globulin (TBG), transthyretin, and albumin)
CnssPenetration:
Limited (T4 crosses BBB, but T3 is more active in CNS)
Elimination:
HalfLife:
6-7 days (euthyroid); 9-10 days (hypothyroid); 3-4 days (hyperthyroid)
Clearance:
Approximately 0.05 L/hr
ExcretionRoute:
Renal (approximately 80% as metabolites), fecal (approximately 20% as metabolites)
Unchanged:
<1% (renal)
Pharmacodynamics
OnsetOfAction:
Gradual, over several days to weeks.
PeakEffect:
Clinical effects typically seen within 3-4 weeks, full therapeutic effect may take 4-6 weeks.
DurationOfAction:
Due to long half-life, effects persist for several days after discontinuation.
Safety & Warnings
BLACK BOX WARNING
Thyroid hormones, including Euthyrox, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when 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 change
Diarrhea, stomach cramps, or vomiting
Mood changes, such as feeling irritable, nervous, excitable, anxious, or restless
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. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you notice any of the following side effects or any other unusual symptoms, contact your doctor for advice:
* Hair loss (usually temporary and resolves on its own within the first few months of treatment)
Reporting Side Effects
If you have questions or concerns about side effects, don't hesitate to reach out to your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
While rare, some people may experience severe and potentially life-threatening side effects when 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 change
Diarrhea, stomach cramps, or vomiting
Mood changes, such as feeling irritable, nervous, excitable, anxious, or restless
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. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you notice any of the following side effects or any other unusual symptoms, contact your doctor for advice:
* Hair loss (usually temporary and resolves on its own within the first few months of treatment)
Reporting Side Effects
If you have questions or concerns about side effects, don't hesitate to reach out to 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 medicine (hyperthyroidism): rapid heart rate, palpitations, chest pain, nervousness, sweating, tremor, insomnia, weight loss, diarrhea.
- Symptoms of too little medicine (hypothyroidism): extreme fatigue, unexplained weight gain, constipation, feeling cold, dry skin, hair loss, depression, slow heart rate.
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 with your doctor.
Additionally, to ensure safe treatment, tell your doctor and pharmacist about:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
All your health problems
It is vital to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting 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 with your doctor.
Additionally, to ensure safe treatment, tell your doctor and pharmacist about:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
All your health problems
It is vital to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
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 uninterrupted 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.
Special Considerations
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 recommended.
If you take biotin or any products containing biotin, stop taking it 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 osteoporosis (weak bones), particularly after menopause. Discuss your risk factors with your doctor and ask about any concerns you may have.
This medication may also affect fertility, potentially making it difficult to become pregnant or father 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 and Breastfeeding
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.
Pediatric Patients
If you are giving this medication to a child and their weight changes, consult with your doctor, as the dosage may need to be adjusted. Never give your child more of this medication than prescribed, as this may increase the risk of severe side effects.
In some cases, this medication may affect growth in children and teenagers. 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 uninterrupted 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.
Special Considerations
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 recommended.
If you take biotin or any products containing biotin, stop taking it 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 osteoporosis (weak bones), particularly after menopause. Discuss your risk factors with your doctor and ask about any concerns you may have.
This medication may also affect fertility, potentially making it difficult to become pregnant or father 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 and Breastfeeding
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.
Pediatric Patients
If you are giving this medication to a child and their weight changes, consult with your doctor, as the dosage may need to be adjusted. Never give your child more of this medication than prescribed, as this may increase the risk of severe side effects.
In some cases, this medication may affect growth in children and teenagers. Regular growth checks may be necessary. Consult with your doctor to discuss any concerns.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia
- Arrhythmias (e.g., atrial fibrillation)
- Chest pain (angina)
- Tremor
- Nervousness
- Insomnia
- Diarrhea
- Weight loss
- Heat intolerance
- Fever
- Seizures (rare)
- Coma (rare)
What to Do:
Seek immediate medical attention or call a poison control center (1-800-222-1222). Treatment is supportive and may include beta-blockers for cardiac symptoms, and measures to reduce absorption if recent ingestion.
Drug Interactions
Major Interactions
- Amiodarone (alters thyroid function)
- Antacids (aluminum, magnesium, calcium carbonate) - decrease absorption
- Bile acid sequestrants (cholestyramine, colestipol) - decrease absorption
- Calcium carbonate/supplements - decrease absorption
- Cation exchange resins (e.g., sodium polystyrene sulfonate) - decrease absorption
- Ferrous sulfate/iron supplements - decrease absorption
- Orlistat - decreases absorption
- Proton pump inhibitors (PPIs) - may decrease absorption (due to increased gastric pH)
- Sucralfate - decreases absorption
- Warfarin (enhances anticoagulant effect)
Moderate Interactions
- Anticonvulsants (carbamazepine, phenytoin, phenobarbital) - increase metabolism
- Antidepressants (tricyclics, SSRIs) - may alter thyroid status or increase cardiac effects
- Beta-blockers (e.g., propranolol) - may decrease T4 to T3 conversion
- Corticosteroids - may decrease TSH secretion and T4 to T3 conversion
- Estrogens/Oral Contraceptives - increase TBG, requiring higher levothyroxine dose
- Androgens - decrease TBG, potentially requiring lower levothyroxine dose
- Iodine-containing products (e.g., contrast media) - may alter thyroid function
- Rifampin - increases metabolism
- Soy products - decrease absorption
- Tyrosine kinase inhibitors (e.g., imatinib, sunitinib) - may alter thyroid function
Minor Interactions
- Dietary fiber - may decrease absorption
- Coffee - may decrease absorption
Monitoring
Baseline Monitoring
Thyroid Stimulating Hormone (TSH)
Rationale: Primary indicator of thyroid function and adequacy of replacement therapy.
Timing: Before initiating therapy.
Free Thyroxine (FT4)
Rationale: Assesses circulating unbound T4 levels.
Timing: Before initiating therapy.
Clinical symptoms of hypothyroidism
Rationale: To establish baseline and track improvement.
Timing: Before initiating therapy.
Routine Monitoring
Thyroid Stimulating Hormone (TSH)
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 clinical goals).
Action Threshold: TSH outside target range (e.g., >4.0 mIU/L indicates under-replacement, <0.4 mIU/L indicates over-replacement).
Free Thyroxine (FT4)
Frequency: May be checked if TSH is suppressed or if central hypothyroidism is suspected, or to confirm severe hypothyroidism.
Target: 0.8-1.8 ng/dL (or laboratory specific range).
Action Threshold: FT4 outside target range.
Clinical symptoms (e.g., fatigue, weight, mood, heart rate)
Frequency: At every visit.
Target: Resolution or improvement of hypothyroid symptoms.
Action Threshold: Persistent or worsening hypothyroid symptoms, or development of hyperthyroid symptoms.
Symptom Monitoring
- Symptoms of hypothyroidism (under-replacement): fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, depression, bradycardia, menstrual irregularities.
- Symptoms of hyperthyroidism (over-replacement): palpitations, tachycardia, nervousness, irritability, insomnia, weight loss, heat intolerance, tremor, diarrhea, excessive sweating.
Special Patient Groups
Pregnancy
Levothyroxine is safe and essential during pregnancy. Thyroid hormone requirements often increase during pregnancy, especially in the first trimester. Close monitoring of TSH levels (every 4-6 weeks) and dose adjustments are crucial to maintain maternal euthyroidism, which is vital for fetal neurological development.
Trimester-Specific Risks:
First Trimester:
Increased dose requirements are common; inadequate thyroid hormone can lead to adverse fetal neurodevelopmental outcomes and increased risk of miscarriage.
Second Trimester:
Continued monitoring and dose adjustment.
Third Trimester:
Continued monitoring and dose adjustment; dose may decrease postpartum.
Lactation
Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, which are not clinically significant and do not affect infant thyroid function. It is considered safe for nursing mothers and infants.
Infant Risk:
L1 (Safest)
Pediatric Use
Dosing is weight-based and higher per kg than in adults, especially in neonates and infants, due to rapid growth and higher metabolic rates. Regular monitoring of TSH and FT4 is critical to ensure proper growth and neurodevelopment. Lifelong therapy is usually required for congenital hypothyroidism.
Geriatric Use
Lower initial doses are recommended due to increased sensitivity to thyroid hormones and a higher prevalence of underlying cardiovascular disease. Slower titration is advised to avoid cardiac adverse effects. TSH target range may be slightly higher for very elderly patients.
Clinical Information
Clinical Pearls
- Consistency is key: Take levothyroxine at the same time every day, preferably in the morning on an empty stomach, 30-60 minutes before food or other medications.
- Separate administration: Ensure a 4-hour gap between levothyroxine and calcium, iron, antacids, sucralfate, or bile acid sequestrants.
- Do not crush or chew tablets unless specifically instructed for infants or patients with swallowing difficulties, and only if the formulation allows.
- Monitor TSH regularly: This is the primary lab test to guide dose adjustments. Clinical symptoms are also important.
- Be aware of drug interactions: Many common medications and supplements can affect levothyroxine absorption or metabolism.
- Pregnancy increases dose requirements: Pregnant patients on levothyroxine will almost always need a dose increase, often by 25-50%, and require frequent TSH monitoring.
- Symptoms of over- or under-dosing can mimic other conditions; always consider thyroid status.
- Euthyrox is a specific brand of levothyroxine. While chemically identical to other levothyroxine products, some patients may experience subtle differences in effect when switching brands due to variations in excipients and dissolution. It's generally recommended to stick to one brand once stable.
Alternative Therapies
- Liothyronine (T3) (e.g., Cytomel) - used in specific cases, often for short-term TSH suppression or in combination with T4.
Cost & Coverage
Average Cost:
Varies widely by pharmacy and dosage, typically $10-$50 per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (preferred generic or brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it's 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 be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.