Levo-T 0.2mg(200mcg) 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 products
Pregnancy Category
Category A
FDA Approved
Aug 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, affecting your energy, weight, and many other body 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 cause choking, gagging, or trouble swallowing. If you have one of these products, 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. Check 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. 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 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 cause choking, gagging, or trouble swallowing. If you have one of these products, 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. Check 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. 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 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, preferably 30-60 minutes before breakfast, with a full glass of water. This is crucial for proper absorption.
- Avoid taking with other medications, especially antacids, calcium, iron, or bile acid sequestrants, for at least 4 hours (some recommend longer).
- Take consistently at the same time each day.
- Do not stop taking this medication without consulting your doctor, even if you feel better.
- Inform your doctor about all other medications, supplements, and herbal products you are taking, as many can interact with levothyroxine.
- Regular blood tests (TSH) are essential to ensure the correct dose.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial dose typically 1.6 mcg/kg/day orally once daily 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:
hypothyroidism_initial:
1.6 mcg/kg/day orally once daily. Elderly or patients with cardiac disease: 12.5-25 mcg/day initially.
hypothyroidism_maintenance:
Typically 100-200 mcg/day, adjusted to maintain TSH within normal range.
thyroid_cancer_suppression:
Higher doses, often 2.0-2.7 mcg/kg/day, to suppress TSH below 0.1 mIU/L or to undetectable levels, depending on risk stratification.
Pediatric Dosing
Neonatal:
10-15 mcg/kg/day orally once daily (for congenital hypothyroidism).
Infant:
6-8 mcg/kg/day orally once daily (1-3 months); 5-6 mcg/kg/day (3-6 months); 4-5 mcg/kg/day (6-12 months).
Child:
3-4 mcg/kg/day orally once daily (1-5 years); 2-3 mcg/kg/day (6-12 years).
Adolescent:
1.6 mcg/kg/day orally once daily (12-17 years, or until growth is complete and puberty is attained, then adult dose).
Dose Adjustments
Renal Impairment:
Mild:
No specific dose adjustment required.
Moderate:
No specific dose adjustment required.
Severe:
No specific dose adjustment required.
Dialysis:
No specific dose adjustment required. Levothyroxine is highly protein-bound and not significantly removed by dialysis.
Hepatic Impairment:
Mild:
No specific dose adjustment required.
Moderate:
No specific dose adjustment required.
Severe:
No specific dose adjustment required. Monitor TSH and adjust dose as needed.
Pharmacology
Mechanism of Action
Levothyroxine is a synthetic L-isomer of thyroxine (T4), which is converted to its active metabolite, L-triiodothyronine (T3), in peripheral tissues. T3 and T4 bind to thyroid hormone receptors in the cell nucleus, regulating gene expression and controlling numerous metabolic processes, including protein, fat, and carbohydrate metabolism, and influencing growth and development.
Pharmacokinetics
Absorption:
Bioavailability:
48-80% (variable, affected by food and other medications)
Tmax:
2-4 hours
FoodEffect:
Decreased absorption when taken with food, certain foods (e.g., soy, fiber), or other medications (e.g., calcium, iron, antacids, PPIs). Should be taken on an empty stomach, 30-60 minutes before breakfast.
Distribution:
Vd:
10-13 L
ProteinBinding:
>99% (primarily to thyroxine-binding globulin (TBG), transthyretin, and albumin)
CnssPenetration:
Limited
Elimination:
HalfLife:
6-7 days (euthyroid); 9-10 days (hypothyroid); 3-4 days (hyperthyroid)
Clearance:
Approximately 0.05 L/hour
ExcretionRoute:
Primarily renal (approximately 80% as metabolites), with some fecal excretion.
Unchanged:
<1% (renal)
Pharmacodynamics
OnsetOfAction:
Gradual, clinical effects typically seen within 3-5 days, but full therapeutic effect may take 4-6 weeks due to long half-life.
PeakEffect:
4-6 weeks (after dose stabilization)
DurationOfAction:
Effects persist for several weeks after discontinuation due to long half-life and tissue binding.
Safety & Warnings
BLACK BOX WARNING
Thyroid hormones, including Levothyroxine, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight reduction. 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
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 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
Additional Side Effects in Children and Infants
Children: Hip or knee pain, or a limp
Infants: Changes in the shape of the head and face
Other Possible Side Effects
Not everyone experiences side effects, and many people have only minor or no side effects at all. However, 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, contact 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 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
Additional Side Effects in Children and Infants
Children: Hip or knee pain, or a limp
Infants: Changes in the shape of the head and face
Other Possible Side Effects
Not everyone experiences side effects, and many people have only minor or no side effects at all. However, 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, contact 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, excessive sweating, heat intolerance, nervousness, anxiety, tremor, unexplained weight loss, diarrhea, insomnia.
- Symptoms of too little thyroid hormone (hypothyroidism, if dose is too low): extreme fatigue, unexplained weight gain, constipation, cold intolerance, 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, 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
Any health problems you have
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, 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
Any health problems you have
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 continuous 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 your 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 a higher risk of osteoporosis.
This medication may also affect fertility, potentially making it more difficult to become pregnant or father a child. If you plan to conceive, consult with your doctor before starting treatment.
Age-Related Considerations
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. Your doctor will discuss the benefits and risks of this medication with you, considering both your health and the health of 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 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 to monitor any potential effects. Consult with your doctor to discuss the potential risks and benefits of this medication for your child.
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. 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 your 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 a higher risk of osteoporosis.
This medication may also affect fertility, potentially making it more difficult to become pregnant or father a child. If you plan to conceive, consult with your doctor before starting treatment.
Age-Related Considerations
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. Your doctor will discuss the benefits and risks of this medication with you, considering both your health and the health of 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 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 to monitor any potential effects. Consult with your doctor to discuss the potential risks and benefits of this medication for your child.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia
- Arrhythmias (e.g., atrial fibrillation)
- Chest pain (angina)
- Tremor
- Nervousness
- Irritability
- Insomnia
- Excessive sweating
- Heat intolerance
- Fever
- Weight loss
- Diarrhea
- Vomiting
- Seizures (rare)
- Heart failure (in susceptible individuals)
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 cardiovascular symptoms, and measures to reduce absorption if ingestion was recent.
Drug Interactions
Major Interactions
- Amiodarone (may alter thyroid function, requiring dose adjustment)
- Antacids (aluminum, magnesium, calcium carbonate) - decrease absorption
- Bile acid sequestrants (cholestyramine, colestipol) - decrease absorption
- Calcium carbonate - decreases absorption
- Cation exchange resins (sevelamer, sodium polystyrene sulfonate) - decrease absorption
- Iron supplements - decrease absorption
- Orlistat - decreases absorption
- Proton pump inhibitors (PPIs) - may decrease absorption due to increased gastric pH
- Sucralfate - decreases absorption
- Soy products (large amounts) - may decrease absorption
- Tyrosine kinase inhibitors (e.g., imatinib, sunitinib) - may increase levothyroxine requirements
- Warfarin - levothyroxine may enhance anticoagulant effect, increasing bleeding risk
Moderate Interactions
- Anticonvulsants (carbamazepine, phenytoin, phenobarbital) - increase levothyroxine metabolism
- Beta-blockers (e.g., propranolol) - may inhibit T4 to T3 conversion
- Corticosteroids - may inhibit T4 to T3 conversion
- Estrogens (oral) - increase TBG, increasing levothyroxine requirements
- Furosemide (high dose) - may displace T4 from protein binding
- Lithium - may cause hypothyroidism
- Oral contraceptives - increase TBG, increasing levothyroxine requirements
- Rifampin - increases levothyroxine metabolism
- SSRIs (e.g., sertraline) - may increase levothyroxine requirements
- Theophylline - levothyroxine may increase theophylline clearance
Minor Interactions
- Dietary fiber - may decrease absorption
Monitoring
Baseline Monitoring
Thyroid Stimulating Hormone (TSH)
Rationale: Primary diagnostic and monitoring tool for hypothyroidism.
Timing: Before initiating therapy.
Free Thyroxine (Free T4)
Rationale: Assesses circulating unbound T4 levels, useful in certain conditions (e.g., central hypothyroidism, pregnancy, or when TSH is unreliable).
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 (euthyroid range); target may vary based on patient age, comorbidities, and specific conditions (e.g., thyroid cancer suppression).
Action Threshold: Adjust dose if TSH is outside target range.
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 normal range).
Action Threshold: Adjust dose if T4 is outside target range or inconsistent with TSH.
Clinical symptoms of hypothyroidism/hyperthyroidism
Frequency: At each visit.
Target: Resolution of hypothyroid symptoms (fatigue, weight gain, constipation, cold intolerance) and absence of hyperthyroid symptoms (palpitations, anxiety, weight loss, heat intolerance).
Action Threshold: Evaluate for dose adjustment or other causes if symptoms persist or new symptoms appear.
Symptom Monitoring
- Fatigue
- Weight changes (gain or loss)
- Constipation
- Cold or heat intolerance
- Dry skin
- Hair loss
- Bradycardia or tachycardia
- Palpitations
- Anxiety
- Tremor
- Menstrual irregularities
- Depression
- Memory impairment
Special Patient Groups
Pregnancy
Levothyroxine is Category A and is essential for fetal neurological development. Hypothyroidism during pregnancy can lead to adverse maternal and fetal outcomes. Dose requirements often increase during pregnancy (by 25-50% or more), typically starting in the first trimester. TSH should be monitored every 4-6 weeks.
Trimester-Specific Risks:
First Trimester:
Untreated maternal hypothyroidism is associated with increased risk of miscarriage, preterm birth, preeclampsia, and impaired neurocognitive development in the fetus.
Second Trimester:
Continued risk of adverse outcomes if hypothyroidism is not adequately treated.
Third Trimester:
Continued risk of adverse outcomes if hypothyroidism is not adequately treated. Dose adjustments may still be needed.
Lactation
Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, and it is not expected to cause adverse effects in breastfed infants. It is considered safe for use during lactation.
Infant Risk:
Low risk.
Pediatric Use
Dosing is weight-based and higher per kg in younger children due to higher metabolic rates and rapid growth. Regular monitoring of TSH and Free T4 is crucial to ensure proper growth and neurocognitive development. Crushing tablets and mixing with a small amount of water or breast milk/formula is acceptable for infants and young children; avoid mixing with soy formula or iron/calcium supplements.
Geriatric Use
Lower initial doses (e.g., 12.5-25 mcg/day) are recommended, especially in patients with underlying cardiac disease, to avoid precipitating cardiac events. Dose adjustments should be made cautiously and gradually. TSH monitoring remains the primary guide.
Clinical Information
Clinical Pearls
- Consistency is key: Advise patients to take levothyroxine at the same time each day, preferably in the morning, 30-60 minutes before food or other medications.
- Many drug interactions: Emphasize the importance of separating levothyroxine administration from calcium, iron, antacids, PPIs, and other interacting medications by at least 4 hours.
- Brand vs. Generic: While generally interchangeable, some patients may experience fluctuations in TSH when switching between different generic manufacturers or between brand and generic. If a patient is stable on a specific product, it's often best to maintain that product.
- Symptoms vs. Labs: Always consider both clinical symptoms and laboratory values (TSH, Free T4) when adjusting doses.
- Pregnancy: Dose requirements almost always increase during pregnancy. Proactive dose increases and frequent TSH monitoring are essential.
- Myxedema Coma: A life-threatening complication of severe, untreated hypothyroidism, requiring immediate IV levothyroxine and supportive care.
- Subclinical Hypothyroidism: Treatment decisions depend on TSH levels, symptoms, age, and comorbidities. Not all cases require treatment.
Alternative Therapies
- Liothyronine (T3) - used rarely as monotherapy for hypothyroidism, primarily in specific cases like thyroid cancer preparation or severe myxedema, due to its shorter half-life and potential for more fluctuating T3 levels.
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (for 200mcg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic) or Tier 2 (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 this 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 emergency medical attention. When seeking help, be prepared to provide details about the medication, including the amount taken and the time it happened, to help healthcare professionals provide the best possible care.