Levo-T 175mcg 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 to treat an underactive thyroid (hypothyroidism), a condition where your thyroid doesn't make enough hormone. Taking this medication helps your body function properly, regulating your metabolism, energy levels, and other important body processes.
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 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 your medication 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 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 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 your medication 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 in the morning.
- Take it on an empty stomach, at least 30-60 minutes before breakfast or any other food, beverages (other than water), or medications.
- Take it with a full glass of water.
- Do not take it at the same time as antacids, iron supplements, calcium supplements, or bile acid sequestrants. Separate these by at least 4 hours.
- Do not switch between different brands or generic versions of levothyroxine without consulting your doctor, as doses may not be equivalent.
- Inform your doctor if you become pregnant, as your dose may need to be adjusted.
- Continue taking this medication even if you feel well; it is a lifelong treatment for most people.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
1.6 mcg/kg/day orally once daily
Dose Range:
25 - 300 mg
Condition-Specific Dosing:
initial_hypothyroidism:
Starting dose typically 50-100 mcg/day, adjusted by 12.5-25 mcg increments every 4-6 weeks based on TSH.
severe_long_standing_hypothyroidism:
Initial dose 12.5-25 mcg/day, increased gradually.
elderly_cardiac_disease:
Initial dose 12.5-25 mcg/day, increased gradually.
myxedema_coma:
IV administration, typically 200-500 mcg loading dose, then 50-100 mcg daily.
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 until growth complete, then adult dose)
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed
Dialysis:
No adjustment needed; not significantly dialyzable.
Hepatic Impairment:
Mild:
No specific adjustment needed, monitor TSH.
Moderate:
No specific adjustment needed, monitor TSH.
Severe:
No specific adjustment needed, monitor TSH.
Pharmacology
Mechanism of Action
Levothyroxine (L-thyroxine) is a synthetic form of thyroxine (T4), a naturally occurring thyroid hormone. It 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:
48-79% (variable, affected by food, other medications)
Tmax:
2-4 hours
FoodEffect:
Decreased and delayed absorption when taken with food. Should be taken on an empty stomach.
Distribution:
Vd:
10-13 L
ProteinBinding:
>99% (primarily to thyroxine-binding globulin (TBG), transthyretin, and albumin)
CnssPenetration:
Limited (T4 crosses BBB to a limited extent, T3 more readily)
Elimination:
HalfLife:
6-7 days (euthyroid); 9-10 days (hypothyroid); 3-4 days (hyperthyroid)
Clearance:
Approximately 0.01 L/hour/kg
ExcretionRoute:
Renal (approximately 80% as metabolites), fecal (approximately 20% as metabolites and unchanged drug)
Unchanged:
Approximately 20% of administered dose excreted unchanged in feces.
Pharmacodynamics
OnsetOfAction:
Gradual, clinical effects typically seen within 3-5 days, but full therapeutic effect may take 4-6 weeks.
PeakEffect:
4-6 weeks (based on TSH normalization)
DurationOfAction:
Long, 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 medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Chest pain or pressure
Fast or abnormal heartbeat
Shortness of breath
Sudden weight gain or swelling in the arms or legs
Headache
Feeling tired or weak
Changes in appetite
Unintentional weight change
Diarrhea, stomach cramps, or vomiting
Mood changes, such as 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 period (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. However, many people experience no side effects or only mild ones. 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
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 medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Chest pain or pressure
Fast or abnormal heartbeat
Shortness of breath
Sudden weight gain or swelling in the arms or legs
Headache
Feeling tired or weak
Changes in appetite
Unintentional weight change
Diarrhea, stomach cramps, or vomiting
Mood changes, such as 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 period (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. However, many people experience no side effects or only mild ones. 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
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 thyroid hormone (hyperthyroidism): rapid heart rate, palpitations, chest pain, shortness of breath, excessive sweating, heat intolerance, nervousness, anxiety, tremor, insomnia, unexplained weight loss, diarrhea.
- Symptoms of too little thyroid hormone (hypothyroidism) despite treatment: persistent fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss, depression, muscle aches, 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 and medications with your doctor.
To ensure your safety, 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
* Your health problems
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm it is safe to do so.
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, 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
* Your health problems
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm it is safe to do so.
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 run out of this medication, as it may take several weeks to experience its full effects.
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 osteoporosis (weak bones), 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 weight changes, consult with 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, 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 run out of this medication, as it may take several weeks to experience its full effects.
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 osteoporosis (weak bones), 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 weight changes, consult with 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, so be sure to discuss this with your doctor.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia
- Arrhythmias
- Chest pain (angina)
- Tremor
- Nervousness
- Irritability
- Insomnia
- Diarrhea
- Weight loss
- Increased appetite
- Fever
- Heat intolerance
- Sweating
What to Do:
Seek immediate medical attention or call a poison control center (e.g., 1-800-222-1222). Treatment is symptomatic and supportive, often involving beta-blockers for cardiac effects.
Drug Interactions
Major Interactions
- Amiodarone (can cause hypo- or hyperthyroidism, monitor thyroid function)
- Warfarin (levothyroxine may increase anticoagulant effect, monitor INR)
- Tyrosine kinase inhibitors (e.g., imatinib, sunitinib, sorafenib - may decrease levothyroxine efficacy, monitor TSH)
- Orlistat (may decrease levothyroxine absorption, separate administration by at least 4 hours)
- Sucralfate (may decrease levothyroxine absorption, separate administration by at least 4 hours)
Moderate Interactions
- Antacids (aluminum, magnesium, calcium carbonate - decrease absorption, separate by 4 hours)
- Iron supplements (ferrous sulfate - decrease absorption, separate by 4 hours)
- Calcium supplements (calcium carbonate, calcium citrate - decrease absorption, separate by 4 hours)
- Bile acid sequestrants (cholestyramine, colestipol, colesevelam - decrease absorption, separate by 4-6 hours)
- Proton pump inhibitors (e.g., omeprazole - may decrease absorption due to increased gastric pH, monitor TSH)
- H2 receptor blockers (e.g., ranitidine - may decrease absorption due to increased gastric pH, monitor TSH)
- Soy products (may decrease absorption, monitor TSH)
- Dietary fiber (may decrease absorption, separate administration)
- Rifampin (increases levothyroxine metabolism, may require dose increase)
- Phenytoin (increases levothyroxine metabolism, may require dose increase)
- Carbamazepine (increases levothyroxine metabolism, may require dose increase)
- Sertraline (may increase levothyroxine requirements, monitor TSH)
- Estrogens (increase TBG, may increase levothyroxine requirements)
- Androgens (decrease TBG, may decrease levothyroxine requirements)
- Beta-blockers (may decrease peripheral conversion of T4 to T3)
- Corticosteroids (may decrease peripheral conversion of T4 to T3)
Minor Interactions
- Coffee (may decrease absorption, separate administration)
Monitoring
Baseline Monitoring
Thyroid Stimulating Hormone (TSH)
Rationale: Primary indicator of thyroid function and adequacy of levothyroxine replacement.
Timing: Before initiating therapy.
Free Thyroxine (FT4)
Rationale: To assess baseline thyroid hormone levels.
Timing: Before initiating therapy.
Clinical symptoms of hypothyroidism
Rationale: To establish baseline symptom severity.
Timing: Before initiating therapy.
Routine Monitoring
Thyroid Stimulating Hormone (TSH)
Frequency: Every 4-6 weeks after initiation or dose change, then every 6-12 months once stable.
Target: 0.4-4.0 mIU/L (individualized based on patient age, comorbidities, and specific condition being treated).
Action Threshold: TSH outside target range requires dose adjustment.
Free Thyroxine (FT4)
Frequency: May be monitored if TSH is suppressed or in central hypothyroidism, or if TSH is not reliable.
Target: 0.8-1.8 ng/dL (or laboratory specific range).
Action Threshold: FT4 outside target range may indicate need for dose adjustment.
Clinical symptoms of hypo/hyperthyroidism
Frequency: At every visit.
Target: Resolution of hypothyroid symptoms, absence of hyperthyroid symptoms.
Action Threshold: Persistent symptoms of hypothyroidism or emergence of hyperthyroid symptoms (e.g., palpitations, anxiety, weight loss) require evaluation and potential dose adjustment.
Symptom Monitoring
- Fatigue
- Weight gain
- Cold intolerance
- Constipation
- Dry skin
- Hair loss
- Bradycardia
- Depression
- Muscle aches
- Memory impairment
- Palpitations
- Anxiety
- Irritability
- Weight loss (unexplained)
- Heat intolerance
- Diarrhea
- Tremor
- Tachycardia
- Insomnia
Special Patient Groups
Pregnancy
Levothyroxine is Category A and is safe and essential during pregnancy. Thyroid hormone requirements often increase during pregnancy (by 25-50% or more) due to increased TBG, placental deiodination, and fetal thyroid hormone needs. Close monitoring of TSH is crucial.
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 offspring.
Second Trimester:
Continued need for increased dosage; fetal thyroid gland begins to function, but maternal thyroid hormone remains important.
Third Trimester:
Continued need for increased dosage; essential for fetal brain development.
Lactation
Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, which are not clinically significant and do not affect infant thyroid function. It is considered safe for the nursing infant.
Infant Risk:
L1 (Safest) - No known risk to the infant.
Pediatric Use
Dosing is weight-based and higher per kg than in adults, especially in infants and young children, due to higher metabolic rates and critical need for thyroid hormone for normal growth and neurodevelopment. Regular monitoring of TSH and FT4 is essential. Untreated congenital hypothyroidism can lead to irreversible intellectual disability.
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 exacerbating cardiac conditions. Dose adjustments should be made in smaller increments and less frequently. Monitor for signs of cardiac toxicity.
Clinical Information
Clinical Pearls
- Always administer levothyroxine on an empty stomach, preferably 30-60 minutes before breakfast, to ensure consistent absorption.
- Advise patients to take levothyroxine with water only, avoiding coffee, juice, or other beverages, which can impair absorption.
- Emphasize the importance of consistent timing of administration each day.
- Educate patients about potential interactions with other medications (e.g., antacids, iron, calcium) and the need to separate administration by several hours.
- Stress that levothyroxine is a lifelong medication for most patients with hypothyroidism and should not be stopped without consulting a physician.
- Explain that it takes 4-6 weeks for TSH levels to stabilize after a dose change, so dose adjustments are not made more frequently than this.
- In patients with known cardiovascular disease, start with a very low dose and titrate slowly to avoid precipitating angina or arrhythmias.
- For patients who have difficulty swallowing tablets, some formulations can be crushed and suspended in water, but always verify with the specific product's instructions or pharmacist.
- Monitor for both hypothyroid and hyperthyroid symptoms, as both indicate a need for dose adjustment.
Alternative Therapies
- Liothyronine (T3) - used in specific cases, e.g., myxedema coma, or for short-term TSH suppression before radioactive iodine scan.
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 (generic), 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 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 details about the medication taken, the amount, and the time it happened.