Levothyroxine 0.150mg (150mcg) Tab
Overview
What is this medicine?
How to Use This Medicine
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 your 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 or any other food, beverages (other than water), or medications.
- Consistency is key: try to take it at the same time each day.
- Do not take 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.
- Do not stop taking this medication without consulting your doctor, even if you feel better, as it is usually a lifelong treatment.
Available Forms & Alternatives
Available Strengths:
- Levothyroxine 0.100mg(100mcg) Tab
- Levothyroxine 0.075mg (75mcg) Tabs
- Levothyroxine 0.125mg (125mcg) Tab
- Levothyroxine 0.05mg (50mcg) Tab
- Levothyroxine 0.025mg (25mcg) Tab
- Levothyroxine 0.112mg (112mcg) Tabs
- Levothyroxine 0.137mg (137mcg) Tab
- Levothyroxine 0.175mg (175mcg) Tabs
- Levothyroxine 500mcg Inj, 1 Vial
- Levothyroxine Sod 100mcg Inj, 1vial
- Levothyroxine 200mcg Inj, 1 Vial
- Levothyroxine 0.088mg (88mcg) Tab
- Levothyroxine 0.100mg (100mcg) Tab
- Levothyroxine 0.150mg (150mcg) Tab
- Levothyroxine 0.2mg (200mcg) Tab
- Levothyroxine 0.3mg (300mcg) Tab
- Levothyroxine 0.013mg (13mcg) Caps
- Levothyroxine 0.025mg (25mcg) Caps
- Levothyroxine 0.05mg (50mcg) Caps
- Levothyroxine 0.075mg (75mcg) Caps
- Levothyroxine 0.088mg (88mcg) Caps
- Levothyroxine 0.100mg (100mcg) Caps
- Levothyroxine 0.112mg (112mcg) Caps
- Levothyroxine 0.125mg (125mcg) Caps
- Levothyroxine 0.137mg (137mcg) Caps
- Levothyroxine 0.150mg (150mcg) Caps
- Levothyroxine 0.175mg (175mcg) Caps
- Levothyroxine 0.2mg (200mcg) Caps
- Levothyroxine 0.125mg (125mcg) Tabs
- Levothyroxine 100mcg/5ml Inj, 5ml
- Levothyroxine 100mcg/ml Inj, 1ml
- Levothyroxine 500mg/5ml Inj, 5ml
- Levothyroxine 200mcg/5ml Inj, 5ml
Dosing & Administration
Adult Dosing
Condition-Specific Dosing:
Pediatric Dosing
Dose Adjustments
Renal Impairment:
Hepatic Impairment:
Pharmacology
Mechanism of Action
Pharmacokinetics
Absorption:
Distribution:
Elimination:
Pharmacodynamics
Safety & Warnings
BLACK BOX WARNING
Side Effects
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 help right away:
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
Vomiting
Mood changes, such as:
+ Irritability
+ Nervousness
+ Excitability
+ Anxiety
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
+ Limping
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 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, nervousness, tremors, excessive sweating, heat intolerance, unexplained weight loss, diarrhea, insomnia.
- Symptoms of too little thyroid hormone (hypothyroidism) if dose is too low or missed: extreme fatigue, weight gain, constipation, dry skin, hair loss, feeling cold, depression.
Before Using This Medicine
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.
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
Your overall health status
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 adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
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. 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.
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 making it difficult to become pregnant or father a child. If you plan to conceive, consult 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
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 for you and your baby.
Special Considerations for Children
If your child is taking this medication and experiences a change in weight, consult 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. Consult your doctor to discuss any concerns.
Overdose Information
Overdose Symptoms:
- Palpitations
- Tachycardia (rapid heart rate)
- Arrhythmias (irregular heartbeat)
- Chest pain (angina)
- Tremor
- Nervousness
- Insomnia
- Diarrhea
- Weight loss
- Fever
- Heat intolerance
- Sweating
What to Do:
Seek immediate medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222.
Drug Interactions
Contraindicated Interactions
- Acute myocardial infarction
- Uncorrected adrenal insufficiency
- Untreated thyrotoxicosis
Major Interactions
- Amiodarone (can alter thyroid function)
- Antacids (aluminum, magnesium, calcium) - decrease absorption
- Bile acid sequestrants (cholestyramine, colestipol) - decrease absorption
- Calcium carbonate/supplements - decrease absorption
- Iron supplements - decrease absorption
- Orlistat - decrease absorption
- Proton pump inhibitors (e.g., omeprazole) - decrease absorption
- Sucralfate - decrease absorption
- Soy products/formula - decrease absorption
- Warfarin (increased anticoagulant effect, monitor INR)
- Insulin/oral hypoglycemics (increased requirements, monitor glucose)
- Enzyme-inducing anticonvulsants (phenytoin, carbamazepine, phenobarbital) - increase levothyroxine metabolism
- Rifampin - increases levothyroxine metabolism
- Sertraline - may decrease levothyroxine efficacy
Moderate Interactions
- Beta-blockers (may decrease T4 to T3 conversion)
- Estrogens (oral) - increase TBG, may increase levothyroxine requirement
- Androgens - decrease TBG, may decrease levothyroxine requirement
- Corticosteroids - may decrease T4 to T3 conversion
- Digoxin (may decrease digoxin levels)
- Theophylline (may decrease theophylline clearance)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Rationale: Primary diagnostic and monitoring tool for hypothyroidism.
Timing: Before initiating therapy.
Rationale: Assesses circulating unbound T4 levels, useful in certain conditions (e.g., central hypothyroidism, altered protein binding).
Timing: Before initiating therapy.
Rationale: To establish baseline symptom severity and track improvement.
Timing: Before initiating therapy.
Rationale: To assess for underlying cardiac disease, especially in elderly or those with known heart conditions, as thyroid hormone replacement can exacerbate cardiac symptoms.
Timing: Before initiating therapy, particularly in older adults or those with cardiac risk factors.
Routine Monitoring
Frequency: Every 4-6 weeks until stable, then every 6-12 months once stable.
Target: 0.4-4.0 mIU/L (individualized based on age, comorbidities, and specific clinical situation).
Action Threshold: Adjust dose if TSH is outside target range; higher TSH indicates under-replacement, lower TSH indicates over-replacement.
Frequency: May be monitored if TSH is suppressed (e.g., central hypothyroidism) or if there are concerns about TSH reliability. Less frequently than TSH.
Target: Reference range (e.g., 0.8-1.8 ng/dL), individualized.
Action Threshold: Adjust dose if Free T4 is outside target range, especially if TSH is not reliable.
Frequency: At each visit.
Target: Resolution or improvement of hypothyroid symptoms.
Action Threshold: Persistent or worsening symptoms despite normal TSH may warrant further investigation or dose adjustment.
Symptom Monitoring
- Fatigue
- Weight changes (gain or loss)
- Cold intolerance
- Constipation
- Dry skin
- Hair loss
- Bradycardia
- Depression
- Memory impairment
- Muscle aches
- Menstrual irregularities
- Nervousness
- Palpitations
- Heat intolerance
- Tremor
- Diarrhea
- Insomnia
- Weight loss (unintended)
Special Patient Groups
Pregnancy
Levothyroxine is essential for normal fetal development and is safe to use during pregnancy. Thyroid hormone requirements often increase during pregnancy, requiring dose adjustments.
Trimester-Specific Risks:
Lactation
Levothyroxine is considered safe during breastfeeding. Only small amounts are excreted into breast milk, and it does not adversely affect the infant.
Pediatric Use
Essential for normal growth and development. Dosing is weight-based and generally higher per kilogram in younger children due to higher metabolic rates. Close monitoring of TSH and clinical status is crucial to ensure proper development.
Geriatric Use
Lower starting doses are recommended due to increased sensitivity to thyroid hormones and a higher prevalence of underlying cardiac disease. Titrate dose slowly and monitor for cardiac symptoms. TSH target range may be slightly higher in very elderly patients.
Clinical Information
Clinical Pearls
- Take levothyroxine consistently at the same time each day, preferably 30-60 minutes before breakfast with water, to ensure optimal and consistent absorption.
- Separate administration from calcium, iron, antacids, and other interacting medications by at least 4 hours.
- Do not switch between different brands or generic formulations without consulting your doctor, as bioavailability can vary, potentially requiring dose adjustments.
- Thyroid function tests (TSH, Free T4) should be monitored regularly, especially after dose changes, to ensure therapeutic levels.
- Patients should be educated on symptoms of both under- and over-treatment to report to their healthcare provider.
Alternative Therapies
- Liothyronine (T3, synthetic)
- Liotrix (T4/T3 combination, synthetic)
- Desiccated Thyroid Extract (natural, animal-derived T4/T3 combination)