Levo-T 0.125mg (125mcg) 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 hormones
Pregnancy Category
Category A
FDA Approved
Jul 1949
DEA Schedule
Not Controlled
Overview
What is this medicine?
Levo-T is a medicine that replaces a hormone normally made by your thyroid gland. It's used to treat an underactive thyroid (hypothyroidism) or to help manage certain types of thyroid cancer. It helps your body's metabolism work properly.
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 the 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 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 this medication.
If you take other medications, they may need to be taken at a different time than this 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 this 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 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 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 the 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 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 this medication.
If you take other medications, they may need to be taken at a different time than this 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 this 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 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 this medicine exactly as prescribed by your doctor, usually once a day in the morning.
- Take it on an empty stomach, at least 30-60 minutes before breakfast and any other medications, supplements, or food.
- Avoid taking calcium, iron, antacids, or fiber supplements within 4 hours of taking levothyroxine, as they can interfere with absorption.
- Inform your doctor about all other medications, supplements, and herbal products you are taking, as many can interact with levothyroxine.
- Do not stop taking this medicine without consulting your doctor, even if you feel better. This is usually a lifelong treatment.
- Regular blood tests (TSH) are crucial to ensure you are on 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. Dose adjusted based on TSH levels.
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
hypothyroidism:
Initial: 1.6 mcg/kg/day orally once daily. Adjust by 12.5-25 mcg increments every 4-6 weeks based on TSH. Maintenance: 50-200 mcg/day.
subclinical_hypothyroidism:
Initial: 25-75 mcg/day orally once daily. Adjust based on TSH.
myxedema_coma:
Initial: 300-500 mcg IV bolus, then 50-100 mcg IV daily until oral therapy can be resumed.
thyroid_cancer_tsh_suppression:
Higher doses, typically 2-2.5 mcg/kg/day, to achieve TSH suppression below 0.1 mIU/L or lower, depending on risk.
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:
4-5 mcg/kg/day orally once daily (for 1-5 years); 3-4 mcg/kg/day (for 6-12 years).
Adolescent:
2-3 mcg/kg/day orally once daily (for >12 years or during puberty, until growth is complete, then adult dose).
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Dialysis:
No specific adjustment needed; levothyroxine is highly protein-bound and not significantly removed by dialysis.
Hepatic Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Pharmacology
Mechanism of Action
Levothyroxine sodium 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 and exert metabolic effects through gene transcription and protein synthesis, regulating metabolism, growth, and development.
Pharmacokinetics
Absorption:
Bioavailability:
48-79% (highly variable, affected by food, other drugs, and GI disorders)
Tmax:
2-4 hours
FoodEffect:
Decreased absorption when taken with food, especially fiber, calcium, iron, and certain foods (e.g., soybean flour, cottonseed meal, walnuts, grapefruit juice). Should be taken on an empty stomach, 30-60 minutes before breakfast.
Distribution:
Vd:
10-13 L
ProteinBinding:
Approximately 99% (primarily to thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), 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% of daily T4 degradation), with some fecal excretion (approximately 20%).
Unchanged:
Less than 1% of administered dose is excreted unchanged.
Pharmacodynamics
OnsetOfAction:
Gradual, over several days to weeks.
PeakEffect:
Clinical effects typically seen within 3-4 weeks, with full therapeutic effect achieved after 4-6 weeks (due to long half-life and need for TSH stabilization).
DurationOfAction:
Effects persist for several days after discontinuation due to long half-life.
Safety & Warnings
BLACK BOX WARNING
Thyroid hormones, including Levo-T, 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
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. 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 experience 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
This is not an exhaustive list of potential side effects. If you have questions or concerns, 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 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. 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 experience 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
This is not an exhaustive list of potential side effects. If you have questions or concerns, 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, nervousness, tremors, sweating, heat intolerance, unexplained weight loss, diarrhea, insomnia.
- Symptoms of too little thyroid hormone (hypothyroidism) despite taking medication: persistent fatigue, 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 and medications with your doctor.
To ensure your safety, please disclose the following information to your doctor and pharmacist:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* All your health problems
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to confirm it is safe to do so. This will help prevent potential interactions and ensure the safe use of this medication.
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, please disclose the following information to your doctor and pharmacist:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* All your health problems
Before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to confirm it is safe to do so. This will help prevent potential interactions and ensure the safe use of this medication.
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 avoid any potential issues, 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. 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 osteoporosis (weak bones), particularly after menopause. Discuss your individual 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 are planning to start a family, consult with your doctor before taking this medication.
Special Considerations
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor to discuss the potential benefits and risks to you and your baby.
Pediatric Patients
If your child is taking this medication and experiences any changes in weight, consult with your doctor, as their 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 avoid any potential issues, 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. 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 osteoporosis (weak bones), particularly after menopause. Discuss your individual 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 are planning to start a family, consult with your doctor before taking this medication.
Special Considerations
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor to discuss the potential benefits and risks to you and your baby.
Pediatric Patients
If your child is taking this medication and experiences any changes in weight, consult with your doctor, as their 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
- Nervousness
- Irritability
- Insomnia
- Tremor
- Increased sweating
- Heat intolerance
- Weight loss
- Diarrhea
- Vomiting
- Fever
- 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)
- Antacids (aluminum, magnesium, calcium-containing) - decrease absorption
- Bile acid sequestrants (cholestyramine, colestipol, colesevelam) - decrease absorption
- Calcium carbonate/supplements - decrease absorption
- Cation exchange resins (e.g., sodium polystyrene sulfonate) - decrease absorption
- Iron supplements - decrease absorption
- Orlistat - decrease absorption
- Proton pump inhibitors (PPIs) - may decrease absorption due to increased gastric pH
- Sucralfate - decrease absorption
- Soy products - decrease absorption
- Tyrosine kinase inhibitors (e.g., imatinib, sunitinib, sorafenib) - may increase levothyroxine requirements
- Warfarin (increased anticoagulant effect)
Moderate Interactions
- Anticonvulsants (carbamazepine, phenytoin, phenobarbital) - increase levothyroxine metabolism
- Beta-blockers (e.g., propranolol) - may inhibit peripheral conversion of T4 to T3
- Corticosteroids - may inhibit peripheral conversion of T4 to T3
- Estrogens (oral) - increase TBG, increasing levothyroxine requirements
- Furosemide (>80 mg IV) - 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 - altered clearance
Minor Interactions
- Dietary fiber - may decrease absorption
- Grapefruit juice - may decrease absorption
Monitoring
Baseline Monitoring
Thyroid-stimulating hormone (TSH)
Rationale: To confirm diagnosis of hypothyroidism and establish baseline.
Timing: Prior to initiation of therapy.
Free Thyroxine (Free T4)
Rationale: To assess baseline thyroid hormone levels.
Timing: Prior to initiation of therapy.
Clinical symptoms (e.g., fatigue, weight gain, cold intolerance)
Rationale: To establish baseline symptom severity.
Timing: Prior to initiation of 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 (for primary hypothyroidism, individualized for specific conditions/patients).
Action Threshold: TSH outside target range; adjust dose.
Free Thyroxine (Free T4)
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 range).
Action Threshold: Free T4 outside target range; adjust dose.
Clinical symptoms
Frequency: At each visit.
Target: Resolution or improvement of hypothyroid symptoms.
Action Threshold: Persistent or worsening symptoms, or development of hyperthyroid symptoms; consider dose adjustment or re-evaluation.
Symptom Monitoring
- Symptoms of hypothyroidism (e.g., fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, depression, bradycardia).
- Symptoms of hyperthyroidism (e.g., palpitations, nervousness, tremor, weight loss, heat intolerance, diarrhea, tachycardia, insomnia).
Special Patient Groups
Pregnancy
Levothyroxine is considered safe and essential during pregnancy (Category A). 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 and support fetal neurological development.
Trimester-Specific Risks:
First Trimester:
Increased levothyroxine dose often required due to increased TBG and placental deiodination. Inadequate thyroid hormone can lead to adverse fetal neurodevelopmental outcomes and increased risk of miscarriage, preeclampsia, and preterm birth.
Second Trimester:
Continued monitoring and dose adjustment as needed.
Third Trimester:
Continued monitoring and dose adjustment as needed. Dose may need to be reduced postpartum.
Lactation
Levothyroxine is compatible with breastfeeding (L1). Only small amounts are excreted into breast milk, which are not considered clinically significant to the infant. It is essential for the mother's health and does not pose a risk to the nursing infant.
Infant Risk:
Low risk.
Pediatric Use
Dosing is weight-based and higher per kg in younger children due to higher metabolic rates. Regular monitoring of TSH and Free T4 is critical for proper growth and neurodevelopment. Treatment is lifelong for congenital hypothyroidism.
Geriatric Use
Lower initial doses (e.g., 12.5-25 mcg/day) are often recommended, especially in patients with underlying cardiovascular disease, to avoid precipitating cardiac events. Dose adjustments should be made slowly and cautiously. TSH monitoring remains key.
Clinical Information
Clinical Pearls
- Always take levothyroxine on an empty stomach, 30-60 minutes before breakfast and other medications, to maximize absorption.
- Consistency is key: take it at the same time each day.
- Many medications and supplements (e.g., calcium, iron, antacids, PPIs) can interfere with levothyroxine absorption; separate administration by at least 4 hours.
- TSH is the primary lab test for monitoring levothyroxine therapy in primary hypothyroidism. Free T4 may be useful in central hypothyroidism or if TSH is discordant with clinical picture.
- Patients may require higher doses during pregnancy, with certain medications (e.g., estrogens, some anticonvulsants), or with malabsorption syndromes.
- Symptoms of over- or under-dosing can mimic other conditions; always correlate with TSH levels.
- Do not switch between different brands or generic formulations without consulting a physician, as bioavailability can vary, potentially requiring dose adjustments.
Alternative Therapies
- Liothyronine (synthetic T3) - typically used for short-term TSH suppression or in specific cases of T4 to T3 conversion issues, but not as a sole long-term replacement for primary hypothyroidism due to shorter half-life and fluctuating levels.
Cost & Coverage
Average Cost:
$10-$50 per 30 tablets
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 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.