Levothyroxine 0.137mg (137mcg) Tab
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 hormone
Pregnancy Category
Category A
FDA Approved
Jul 1996
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 levels, weight, body temperature, and many other functions.
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 be more likely to cause choking, gagging, or trouble swallowing. If this is the case, you must take it with a full glass of water. Check with your pharmacist to see if this applies to your specific product.
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.
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. Consult with your doctor or pharmacist to determine the best schedule.
Certain foods, such as soybean flour (found in infant formula), may affect how your medication works in your body. 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 and Brand of 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 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.
What to Do If You Miss a Dose
Take a missed dose 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 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 be more likely to cause choking, gagging, or trouble swallowing. If this is the case, you must take it with a full glass of water. Check with your pharmacist to see if this applies to your specific product.
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.
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. Consult with your doctor or pharmacist to determine the best schedule.
Certain foods, such as soybean flour (found in infant formula), may affect how your medication works in your body. 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 and Brand of 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 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.
What to Do If You Miss a Dose
Take a missed dose 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 on an empty stomach, typically 30-60 minutes before breakfast, with a full glass of water.
- Take at the same time each day for consistent absorption.
- Avoid taking with food, calcium supplements, iron supplements, antacids, or soy products, as these can interfere with absorption. Separate by at least 4 hours.
- Do not switch between different brands or generic formulations without consulting your doctor, as small differences in potency can affect your thyroid levels.
- Inform your doctor about all other medications, supplements, and herbal products you are taking.
- Lifelong therapy is usually required.
Available Forms & Alternatives
Available Strengths:
- Levothyroxine 0.100mg(100mcg) Tab
- Levothyroxine 0.075mg (75mcg) Tabs
- Levothyroxine 0.125mg (125mcg) Tab
- Levothyroxine 0.05mg (50mcg) Tab
- Levothyroxine 0.025mg (25mcg) Tab
- Levothyroxine 0.112mg (112mcg) Tabs
- Levothyroxine 0.137mg (137mcg) Tab
- Levothyroxine 0.175mg (175mcg) Tabs
- Levothyroxine 500mcg Inj, 1 Vial
- Levothyroxine Sod 100mcg Inj, 1vial
- Levothyroxine 200mcg Inj, 1 Vial
- Levothyroxine 0.088mg (88mcg) Tab
- Levothyroxine 0.100mg (100mcg) Tab
- Levothyroxine 0.150mg (150mcg) Tab
- Levothyroxine 0.2mg (200mcg) Tab
- Levothyroxine 0.3mg (300mcg) Tab
- Levothyroxine 0.013mg (13mcg) Caps
- Levothyroxine 0.025mg (25mcg) Caps
- Levothyroxine 0.05mg (50mcg) Caps
- Levothyroxine 0.075mg (75mcg) Caps
- Levothyroxine 0.088mg (88mcg) Caps
- Levothyroxine 0.100mg (100mcg) Caps
- Levothyroxine 0.112mg (112mcg) Caps
- Levothyroxine 0.125mg (125mcg) Caps
- Levothyroxine 0.137mg (137mcg) Caps
- Levothyroxine 0.150mg (150mcg) Caps
- Levothyroxine 0.175mg (175mcg) Caps
- Levothyroxine 0.2mg (200mcg) Caps
- Levothyroxine 0.125mg (125mcg) Tabs
- Levothyroxine 100mcg/5ml Inj, 5ml
- Levothyroxine 100mcg/ml Inj, 1ml
- Levothyroxine 500mg/5ml Inj, 5ml
- Levothyroxine 200mcg/5ml Inj, 5ml
Dosing & Administration
Adult Dosing
Standard Dose:
Initial dose for primary hypothyroidism: 1.6 mcg/kg/day, adjusted based on TSH levels. Average maintenance dose: 100-125 mcg/day.
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
primaryHypothyroidism:
Initial: 1.6 mcg/kg/day. Adjust by 12.5-25 mcg increments every 4-6 weeks. Maintenance: 100-125 mcg/day (average).
cardiacDisease:
Initial: 12.5-25 mcg/day. Titrate slowly with 12.5-25 mcg increments every 4-6 weeks.
TSHSuppression:
Higher doses may be required for TSH suppression in thyroid cancer, typically 2-2.5 mcg/kg/day.
Pediatric Dosing
Neonatal:
0-3 months: 10-15 mcg/kg/day. Adjust based on TSH and T4.
Infant:
3-6 months: 8-10 mcg/kg/day; 6-12 months: 6-8 mcg/kg/day. Adjust based on TSH and T4.
Child:
1-5 years: 5-6 mcg/kg/day; 6-12 years: 4-5 mcg/kg/day. Adjust based on TSH and T4.
Adolescent:
12-17 years: 2-3 mcg/kg/day or 1.6 mcg/kg/day (full adult replacement dose). Adjust based on TSH and T4.
Dose Adjustments
Renal Impairment:
Mild:
No specific dose adjustment generally required.
Moderate:
No specific dose adjustment generally required.
Severe:
No specific dose adjustment generally required.
Dialysis:
No specific dose adjustment generally required. Levothyroxine is highly protein-bound and not significantly dialyzable.
Hepatic Impairment:
Mild:
No specific dose adjustment generally required.
Moderate:
No specific dose adjustment generally required, but monitor thyroid function closely.
Severe:
No specific dose adjustment generally required, but monitor thyroid function closely. Reduced peripheral conversion of T4 to T3 may occur.
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, which regulate gene expression and control numerous metabolic processes, including protein, carbohydrate, and lipid metabolism, and cellular differentiation and growth.
Pharmacokinetics
Absorption:
Bioavailability:
48-80% (average 60-80%), variable among individuals and affected by food, other medications, and gastrointestinal disorders.
Tmax:
2-4 hours (for T4); 24-48 hours (for T3, due to peripheral conversion).
FoodEffect:
Decreased absorption when taken with food, especially fiber, soy, calcium, iron, and coffee. Should be taken on an empty stomach.
Distribution:
Vd:
Approximately 10-13 L (for T4).
ProteinBinding:
Greater than 99% (primarily to thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin).
CnssPenetration:
Limited (T4 crosses the blood-brain barrier to a limited extent, but T3 is more readily transported).
Elimination:
HalfLife:
Approximately 6-7 days (euthyroid individuals); 9-10 days (hypothyroid individuals); 3-4 days (hyperthyroid individuals).
Clearance:
Approximately 0.05 L/hr (euthyroid).
ExcretionRoute:
Primarily renal (approximately 80% as metabolites); some fecal excretion (approximately 20%).
Unchanged:
Less than 1% of the administered dose is excreted unchanged in urine.
Pharmacodynamics
OnsetOfAction:
Gradual, typically 3-5 days for initial effects, but full therapeutic effect and TSH stabilization may take 4-6 weeks.
PeakEffect:
4-6 weeks after initiation or dose adjustment.
DurationOfAction:
Long, due to long half-life; effects persist for several days after discontinuation.
Safety & Warnings
BLACK BOX WARNING
Thyroid hormones, including Levothyroxine, 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
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 immediately or seek emergency medical attention:
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 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. Many people may not experience any side effects or may only have 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 an exhaustive list of 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 immediately or seek emergency medical attention:
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 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. Many people may not experience any side effects or may only have 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 an exhaustive list of 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, insomnia, tremor, excessive sweating, heat intolerance, unexplained weight loss, diarrhea.
- Symptoms of too little thyroid hormone (hypothyroidism) despite treatment: persistent fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, depression, memory problems.
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, provide your doctor and pharmacist with a comprehensive list of all the medications you are taking, including:
Prescription medications
Over-the-counter (OTC) medications
Natural products
* Vitamins
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 dosage 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, provide your doctor and pharmacist with a comprehensive list of all the medications you are taking, including:
Prescription medications
Over-the-counter (OTC) medications
Natural products
* Vitamins
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 dosage 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. Please note that it may take several weeks to experience the full effects of this medication.
Special Considerations
If you have diabetes (high blood sugar), consult with your doctor, as this medication may affect blood sugar control. Your doctor may need to adjust your diabetes medications. Be sure to monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as recommended.
If you are taking biotin or a product 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 developing weak bones (osteoporosis), particularly after menopause. Discuss your individual 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 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 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 both you and your baby.
Pediatric Patients
If your child is taking this medication and experiences a change in weight, consult with your doctor, as the dosage may need to be adjusted. Never give your child more of this medication than prescribed, as this can 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, so be sure to discuss this with your doctor.
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. Please note that it may take several weeks to experience the full effects of this medication.
Special Considerations
If you have diabetes (high blood sugar), consult with your doctor, as this medication may affect blood sugar control. Your doctor may need to adjust your diabetes medications. Be sure to monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as recommended.
If you are taking biotin or a product 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 developing weak bones (osteoporosis), particularly after menopause. Discuss your individual 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 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 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 both you and your baby.
Pediatric Patients
If your child is taking this medication and experiences a change in weight, consult with your doctor, as the dosage may need to be adjusted. Never give your child more of this medication than prescribed, as this can 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, so be sure to discuss this with your doctor.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia
- Arrhythmias
- Chest pain
- Tremor
- Nervousness
- Insomnia
- Diarrhea
- Weight loss
- Fever
- Heat intolerance
- Seizures (rare)
- Coma (rare)
What to Do:
Seek immediate medical attention. Call your local poison control center (e.g., 1-800-222-1222 in the US) or emergency services. Treatment is supportive and may include gastric lavage, activated charcoal, beta-blockers for cardiac symptoms, and other symptomatic measures.
Drug Interactions
Major Interactions
- Amiodarone (may alter thyroid function and metabolism of levothyroxine)
- Oral anticoagulants (e.g., Warfarin - increased anticoagulant effect)
- Tyrosine kinase inhibitors (e.g., Sunitinib, Imatinib - may decrease levothyroxine efficacy)
- Ion exchange resins (e.g., Cholestyramine, Colestipol - significantly decrease absorption of levothyroxine)
- Sucralfate (decreases absorption of levothyroxine)
- Proton pump inhibitors (e.g., Omeprazole - may decrease absorption of levothyroxine)
- H2 blockers (e.g., Ranitidine - may decrease absorption of levothyroxine)
Moderate Interactions
- Antacids (aluminum, magnesium, calcium - decrease absorption of levothyroxine)
- Iron supplements (decrease absorption of levothyroxine)
- Calcium supplements (decrease absorption of levothyroxine)
- Soy products (decrease absorption of levothyroxine)
- Certain anticonvulsants (e.g., Phenytoin, Carbamazepine, Phenobarbital - increase levothyroxine metabolism)
- Rifampin (increases levothyroxine metabolism)
- Sertraline (may increase levothyroxine requirements)
- Beta-blockers (e.g., Propranolol - may decrease peripheral conversion of T4 to T3)
- Estrogens (e.g., oral contraceptives, HRT - increase TBG, potentially increasing levothyroxine requirements)
- Androgens (decrease TBG, potentially decreasing levothyroxine requirements)
- Glucocorticoids (may inhibit TSH secretion and peripheral conversion of T4 to T3)
Minor Interactions
- Dietary fiber (may decrease absorption)
- Coffee (may decrease absorption)
Monitoring
Baseline Monitoring
Thyroid-stimulating hormone (TSH)
Rationale: To confirm diagnosis of hypothyroidism and establish baseline for treatment.
Timing: Prior to initiation of therapy.
Free Thyroxine (Free T4)
Rationale: To assess baseline thyroid hormone levels and differentiate types of hypothyroidism.
Timing: Prior to initiation of therapy.
Clinical symptoms of hypothyroidism
Rationale: To document baseline symptoms for future comparison and assessment of treatment efficacy.
Timing: Prior to initiation of therapy.
Routine Monitoring
Thyroid-stimulating hormone (TSH)
Frequency: Every 4-6 weeks after initiation or dose adjustment, then every 6-12 months once stable.
Target: 0.4-4.0 mIU/L (for primary hypothyroidism, individualized for certain conditions like pregnancy or thyroid cancer suppression).
Action Threshold: Adjust dose if TSH is outside target range or if clinical symptoms persist/worsen.
Free Thyroxine (Free T4)
Frequency: May be checked with TSH, especially if TSH is suppressed or in central hypothyroidism.
Target: 0.8-1.8 ng/dL (or laboratory-specific reference range).
Action Threshold: Adjust dose if Free T4 is outside target range, particularly if TSH is also abnormal.
Clinical symptoms of hypo/hyperthyroidism
Frequency: At every follow-up visit.
Target: Resolution of hypothyroid symptoms without development of hyperthyroid symptoms.
Action Threshold: Evaluate for dose adjustment if symptoms persist or new symptoms develop.
Symptom Monitoring
- Fatigue
- Weight gain
- Constipation
- Cold intolerance
- Dry skin
- Hair loss
- Bradycardia
- Depression
- Memory impairment
- Nervousness
- Irritability
- Palpitations
- Tachycardia
- Heat intolerance
- Weight loss
- Tremor
- Diarrhea
- Insomnia
Special Patient Groups
Pregnancy
Levothyroxine is safe and essential during pregnancy. Thyroid hormone requirements typically increase during pregnancy (by 25-50% or more) due to increased TBG, placental deiodinase activity, and fetal thyroid hormone needs. Close monitoring of TSH (every 4-6 weeks) and dose adjustments are crucial to maintain euthyroidism for optimal maternal and fetal outcomes.
Trimester-Specific Risks:
First Trimester:
Untreated maternal hypothyroidism in the first trimester is associated with increased risk of miscarriage, preterm birth, preeclampsia, and impaired neurocognitive development in the offspring.
Second Trimester:
Continued need for increased dose; fetal thyroid gland begins to function, but maternal thyroid hormone remains important.
Third Trimester:
Dose requirements typically stabilize or slightly increase further. Maintaining euthyroidism is important for fetal growth and development.
Lactation
Levothyroxine is considered safe during breastfeeding. Only small amounts are excreted into breast milk, which are not sufficient to cause adverse effects in the infant or affect infant thyroid function. It is compatible with breastfeeding.
Infant Risk:
L1 (Safest - no increase in adverse effects in infants).
Pediatric Use
Dosing is weight-based and higher per kg than in adults, especially in infants, due to rapid growth and higher metabolic rates. Crucial for normal physical and mental development. Untreated congenital hypothyroidism can lead to irreversible intellectual disability. Regular monitoring of TSH and T4 is essential.
Geriatric Use
Lower starting doses (e.g., 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 cardiac symptoms.
Clinical Information
Clinical Pearls
- Always take levothyroxine consistently on an empty stomach, 30-60 minutes before breakfast, with water, and separate from other medications and supplements by at least 4 hours.
- Do not crush or chew tablets; swallow whole. For infants/children, tablets can be crushed and suspended in a small amount of water or breast milk and given immediately.
- Thyroid function tests (TSH, Free T4) should be performed 4-6 weeks after any dose change or initiation of therapy to allow for steady-state levels to be achieved.
- Patients with central (secondary/tertiary) hypothyroidism should be monitored with Free T4 levels, as TSH may not be a reliable indicator.
- Symptoms of hypothyroidism resolve gradually over several weeks to months after starting treatment.
- Patients should be educated on symptoms of both hypo- and hyperthyroidism to report any changes promptly.
Alternative Therapies
- Liothyronine (T3, e.g., Cytomel) - shorter half-life, more potent, used in specific situations (e.g., thyroid cancer withdrawal, myxedema coma).
- Desiccated Thyroid Extract (e.g., Armour Thyroid, Nature-Throid) - natural thyroid hormone from porcine glands, contains both T4 and T3, variable potency, not recommended as first-line.
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 (generic) or Tier 2-3 (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. 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 information about the medication taken, the amount, and the time it happened.