Levo-T 150mcg 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
Category A
FDA Approved
Jan 1965
DEA Schedule
Not Controlled
Overview
What is this medicine?
Levo-T is a medication 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 medication helps your body function properly, improving symptoms like tiredness, weight gain, and feeling cold.
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 one. 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 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 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 one. 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 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 Levo-T exactly as prescribed by your doctor, usually once a day on an empty stomach, 30-60 minutes before breakfast.
- Take it at the same time each day to help you remember.
- Do not take Levo-T at the same time as antacids, iron supplements, calcium supplements, or certain other medications. Separate doses by at least 4 hours, or as advised by your doctor.
- Avoid switching between different brands of levothyroxine without consulting your doctor, as formulations can vary slightly.
- Continue taking Levo-T even if you feel better; it is a lifelong treatment for most people.
- Inform your doctor about all other medications, supplements, and herbal products you are taking, as they can interact with Levo-T.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial dose typically 1.6 mcg/kg/day orally once daily. Average full replacement dose is 100-125 mcg/day.
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
elderly_cardiac_disease:
Initial dose 12.5-25 mcg/day, titrate slowly.
subclinical_hypothyroidism:
25-75 mcg/day, individualized based on TSH.
Pediatric Dosing
Neonatal:
10-15 mcg/kg/day orally once daily (0-3 months).
Infant:
6-8 mcg/kg/day orally once daily (3-6 months); 5-6 mcg/kg/day (6-12 months).
Child:
4-5 mcg/kg/day orally once daily (1-5 years); 3-4 mcg/kg/day (6-12 years).
Adolescent:
2-3 mcg/kg/day orally once daily (12-17 years); or 1.6 mcg/kg/day if growth and puberty are complete.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Dialysis:
No specific adjustment needed; not significantly dialyzable.
Hepatic Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Pharmacology
Mechanism of Action
Levothyroxine (T4) is a synthetic form of the natural thyroid hormone, thyroxine. It is converted to its active metabolite, L-triiodothyronine (T3), in peripheral tissues. T3 then binds to thyroid hormone receptors in the cell nucleus, regulating gene expression and controlling numerous metabolic processes, including protein synthesis, carbohydrate and lipid metabolism, and cellular respiration. It is essential for normal growth, development, and metabolism.
Pharmacokinetics
Absorption:
Bioavailability:
48-79% (average 60-80%)
Tmax:
2-4 hours
FoodEffect:
Decreased absorption with food, especially fiber, calcium, and iron. 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:
Renal (approximately 80% as metabolites), fecal (approximately 20% as unchanged drug and metabolites)
Unchanged:
Approximately 20% (fecal)
Pharmacodynamics
OnsetOfAction:
Gradual, over several days to weeks
PeakEffect:
3-4 weeks (due to long half-life and need to reach steady state)
DurationOfAction:
Several weeks 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
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 immediate 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 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 women)
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 in some people. While many individuals 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 (commonly occurs in the first few months of treatment and usually resolves on its own)
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. 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.
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 immediate 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 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 women)
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 in some people. While many individuals 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 (commonly occurs in the first few months of treatment and usually resolves on its own)
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects not mentioned here. 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 medication (hyperthyroidism): fast or irregular heartbeat, chest pain, shortness of breath, nervousness, irritability, insomnia, tremor, excessive sweating, unexplained weight loss, diarrhea.
- Symptoms of too little medication (hypothyroidism): persistent fatigue, weight gain, constipation, feeling cold, dry skin, hair loss, depression, muscle aches.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ An overactive thyroid gland
+ A weak adrenal gland
+ Difficulty swallowing
This list is not exhaustive, and it is crucial to discuss all your health problems with your doctor.
Additionally, to ensure your safety, 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 your safety, 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 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.
If you have diabetes (high blood sugar), consult 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 to assess your condition.
When taking biotin or products containing biotin, discontinue use at least 2 days before having your thyroid levels checked to ensure accurate test results.
High doses of this medication may increase the risk of osteoporosis (weak bones), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk of developing osteoporosis.
This medication may affect fertility, potentially leading to difficulties in becoming pregnant or fathering a child. If you plan to conceive, consult your doctor before starting treatment.
If you are 65 years 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 to you and your baby.
Special Considerations for Children
If your child is taking this medication and experiences weight changes, consult your doctor, as the dosage may need to be adjusted. Never give your child more 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 their development. Consult 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.
If you have diabetes (high blood sugar), consult 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 to assess your condition.
When taking biotin or products containing biotin, discontinue use at least 2 days before having your thyroid levels checked to ensure accurate test results.
High doses of this medication may increase the risk of osteoporosis (weak bones), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk of developing osteoporosis.
This medication may affect fertility, potentially leading to difficulties in becoming pregnant or fathering a child. If you plan to conceive, consult your doctor before starting treatment.
If you are 65 years 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 to you and your baby.
Special Considerations for Children
If your child is taking this medication and experiences weight changes, consult your doctor, as the dosage may need to be adjusted. Never give your child more 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 their development. Consult 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
- Increased appetite
- Fever
- Heat intolerance
- Sweating
- 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. Management is supportive and symptomatic, often involving beta-blockers for cardiac symptoms and measures to reduce absorption if recent ingestion.
Drug Interactions
Major Interactions
- Amiodarone (can cause hypo- or hyperthyroidism, alter T4/T3 conversion)
- Oral anticoagulants (e.g., Warfarin - increased anticoagulant effect)
- Tyrosine kinase inhibitors (e.g., Sunitinib, Imatinib - can increase levothyroxine requirements)
- Ion exchange resins (e.g., Cholestyramine, Colestipol - significantly decrease absorption)
- Sucralfate (decreased absorption)
- Sevelamer (decreased absorption)
- Lanthanum (decreased absorption)
Moderate Interactions
- Antacids (aluminum, magnesium, calcium - decreased absorption)
- Iron supplements (decreased absorption)
- Calcium supplements (decreased absorption)
- Proton pump inhibitors (e.g., Omeprazole - may decrease absorption due to altered gastric pH)
- H2 blockers (e.g., Ranitidine - may decrease absorption)
- Soy products (may decrease absorption)
- Dietary fiber (may decrease absorption)
- Estrogens (oral contraceptives, HRT - increase TBG, increasing levothyroxine requirements)
- Androgens (decrease TBG, decreasing levothyroxine requirements)
- Carbamazepine, Phenytoin, Rifampin (increase levothyroxine metabolism)
- Beta-blockers (e.g., Propranolol - may inhibit T4 to T3 conversion)
- Corticosteroids (may inhibit T4 to T3 conversion)
- Antidepressants (tricyclics, SSRIs - may increase cardiac effects of levothyroxine)
- Insulin/Oral Hypoglycemics (levothyroxine may increase blood glucose, requiring dose adjustment of antidiabetics)
Minor Interactions
- Coffee (may decrease absorption if taken concurrently)
Monitoring
Baseline Monitoring
Thyroid Stimulating Hormone (TSH)
Rationale: Primary diagnostic marker for hypothyroidism and to guide initial dosing.
Timing: Prior to initiation of therapy.
Free Thyroxine (FT4)
Rationale: To assess baseline thyroid hormone levels.
Timing: Prior to initiation of therapy.
Clinical symptoms of hypothyroidism
Rationale: To establish baseline symptom severity and track improvement.
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 (individualized based on patient factors, e.g., age, pregnancy, specific conditions).
Action Threshold: Adjust dose if TSH is outside target range; higher TSH indicates need for dose increase, lower TSH indicates need for dose decrease.
Free Thyroxine (FT4)
Frequency: May be monitored if TSH is suppressed or in central hypothyroidism, or if TSH/symptom correlation is poor.
Target: 0.8-1.8 ng/dL (or laboratory specific reference range).
Action Threshold: Adjust dose if FT4 is outside target range, especially if TSH is also abnormal.
Clinical symptoms of hypo/hyperthyroidism
Frequency: At every 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
- Hypothyroid symptoms: fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, depression, bradycardia, muscle aches, menstrual irregularities.
- Hyperthyroid symptoms (due to overtreatment): palpitations, tachycardia, nervousness, irritability, insomnia, weight loss, heat intolerance, tremor, diarrhea, excessive sweating.
Special Patient Groups
Pregnancy
Levothyroxine requirements often increase during pregnancy. It is crucial to maintain euthyroidism for both maternal and fetal health. Category A: Studies in pregnant women have not shown an increased risk of fetal abnormalities.
Trimester-Specific Risks:
First Trimester:
Untreated maternal hypothyroidism in the first trimester is associated with increased risk of miscarriage, preterm birth, and impaired neurocognitive development in the fetus. Dose adjustments are often needed early in pregnancy.
Second Trimester:
Continued monitoring and dose adjustment are necessary to maintain TSH within target range (typically lower than non-pregnant range).
Third Trimester:
Dose requirements may continue to increase. Close monitoring of TSH is essential throughout pregnancy and postpartum.
Lactation
Levothyroxine is considered safe during breastfeeding. It is naturally present in breast milk in small amounts and does not pose a risk to the nursing infant. L1: Safest.
Infant Risk:
Minimal to no risk to the infant. No adverse effects reported in infants of mothers taking levothyroxine.
Pediatric Use
Dosing is weight-based and critical for normal growth and neurocognitive development. Under-treatment can lead to irreversible intellectual disability and growth retardation. Over-treatment can lead to craniosynostosis in infants and accelerated bone maturation. Close monitoring of TSH and FT4 is essential.
Geriatric Use
Lower starting doses (e.g., 12.5-25 mcg/day) are recommended, especially in patients with underlying cardiac disease, due to increased sensitivity to thyroid hormones and potential for cardiac adverse effects. Dose titration should be slower and more cautious. TSH target range may be slightly higher for older adults (e.g., 4-6 mIU/L).
Clinical Information
Clinical Pearls
- Always take levothyroxine on an empty stomach, preferably 30-60 minutes before breakfast, to maximize absorption.
- Separate levothyroxine from calcium, iron, antacids, and other interacting medications by at least 4 hours.
- Consistency is key: take it at the same time every day.
- TSH is the primary lab test for monitoring, but clinical symptoms are also crucial.
- Dose adjustments are often needed during pregnancy, with aging, or if starting/stopping interacting medications.
- Do not use for weight loss in euthyroid individuals due to serious cardiac risks.
- Patients should be advised that it may take several weeks to feel the full effect of a dose change.
Alternative Therapies
- Liothyronine (T3) (e.g., Cytomel, Triostat - used in specific cases, often in combination with levothyroxine or for short-term TSH suppression)
Cost & Coverage
Average Cost:
$15 - $50 per 30 tablets (for common strengths)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (preferred generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. 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 detailed information about the overdose, including the substance taken, the amount, and the time it occurred.