Levothyroxine 0.137mg (137mcg) Caps

Levothyroxine (L-thyroxine) is a synthetic form of thyroxine (T4), a naturally occurring thyroid hormone. It is converted to its active metabolite, liothyronine (T3), in peripheral tissues. Thyroid hormones exert their physiologic actions through control of DNA transcription and protein synthesis. They are involved in normal metabolism, growth, and development, and are essential for maintaining metabolic homeostasis.

Serious 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 changes
Diarrhea, stomach cramps, or vomiting
Mood changes, such as irritability, nervousness, excitability, or 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, 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. 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)
Other side effects not listed here

If you have questions or concerns about side effects, talk to your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

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 safe treatment, 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.

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 your doctor, as this medication may affect blood sugar control. Your doctor may need to adjust your diabetes medications. Monitor your blood sugar levels as instructed by your doctor and undergo regular blood tests as recommended.

When taking biotin or products containing biotin, stop using them 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 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 in getting pregnant or fathering a child. If you plan to conceive, consult your doctor before starting treatment.

Age-Related Considerations

If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.

Pregnancy and Breastfeeding

Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. Your doctor will discuss the benefits and risks of this medication for both you and your baby.

Pediatric Patients

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, so consult your doctor to discuss the potential risks and benefits.

• Bile acid sequestrants (e.g., cholestyramine, colestipol): May significantly decrease levothyroxine absorption. Separate administration by 4-5 hours.
• Ion exchange resins (e.g., sevelamer, patiromer): May decrease levothyroxine absorption. Separate administration by 4-5 hours.
• Sucralfate: May decrease levothyroxine absorption. Separate administration by 4-5 hours.
• Antacids (aluminum and magnesium hydroxide, calcium carbonate): May decrease levothyroxine absorption. Separate administration by 4 hours.
• Iron supplements (ferrous sulfate): May decrease levothyroxine absorption. Separate administration by 4 hours.
• Calcium supplements (calcium carbonate, calcium citrate): May decrease levothyroxine absorption. Separate administration by 4 hours.
• Proton pump inhibitors (e.g., omeprazole, lansoprazole): May decrease levothyroxine absorption due to increased gastric pH. Monitor TSH.
• H2 receptor blockers (e.g., cimetidine, ranitidine): May decrease levothyroxine absorption due to increased gastric pH. Monitor TSH.
• Oral anticoagulants (e.g., warfarin): Levothyroxine may increase the anticoagulant effect of warfarin by increasing the catabolism of vitamin K-dependent clotting factors. Monitor INR closely, especially when initiating or changing levothyroxine dose.
• Antidiabetic agents (insulin, oral hypoglycemics): Thyroid hormones may increase blood glucose levels. Dose adjustments of antidiabetic agents may be necessary.
• Digoxin: Levothyroxine may decrease digoxin levels or effect. Monitor digoxin levels.
• Amiodarone: Can cause both hypothyroidism and hyperthyroidism. May alter thyroid hormone metabolism.
• Beta-blockers (e.g., propranolol): May decrease the peripheral conversion of T4 to T3. Monitor thyroid function.

• Estrogens (oral): May increase TBG levels, leading to increased levothyroxine requirements. Monitor TSH.
• Androgens: May decrease TBG levels, potentially decreasing levothyroxine requirements. Monitor TSH.
• Glucocorticoids: May decrease TBG levels and inhibit T4 to T3 conversion. Monitor TSH.
• Phenytoin, Carbamazepine, Rifampin, Phenobarbital: May increase hepatic metabolism of thyroid hormones, increasing levothyroxine requirements. Monitor TSH.
• SSRIs (e.g., sertraline): May increase levothyroxine requirements in some patients. Monitor TSH.
• Orlistat: May decrease levothyroxine absorption. Separate administration by 4 hours.

• Dietary fiber: May decrease absorption. Take levothyroxine consistently relative to fiber intake.

• Hypothyroid symptoms (e.g., fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, depression, bradycardia)
• Hyperthyroid symptoms (e.g., palpitations, tachycardia, nervousness, tremor, weight loss, heat intolerance, diarrhea, insomnia, chest pain)

Levothyroxine is essential for normal fetal development and is considered safe and necessary during pregnancy. Hypothyroidism during pregnancy can lead to adverse maternal and fetal outcomes. Increased levothyroxine dose is often required during pregnancy due to increased TBG levels and fetal thyroid hormone requirements.

Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, which are not considered clinically significant to the infant.

Essential for normal growth and development. Dosing is weight-based and higher per kg in younger children. Close monitoring of TSH and T4 is crucial to ensure proper brain development and growth. Underdosing can lead to irreversible cognitive impairment and growth retardation. Overdosing can lead to craniosynostosis in infants and accelerated bone maturation.

Older patients may be more sensitive to the effects of levothyroxine, particularly cardiac effects. A lower starting dose and slower titration are recommended. Monitor for signs of cardiac dysfunction (e.g., angina, arrhythmias).

• Always take levothyroxine on an empty stomach, 30-60 minutes before food or other medications, to ensure consistent absorption.
• Do not take levothyroxine at the same time as calcium, iron, antacids, or bile acid sequestrants; separate by at least 4 hours.
• Consistency is key: take it at the same time each day.
• Patients should be advised against switching between different brands or generic formulations without consulting their physician, as bioequivalence can vary, potentially requiring dose adjustments.
• TSH is the primary lab test for monitoring levothyroxine therapy in primary hypothyroidism. Free T4 may be useful in certain situations (e.g., central hypothyroidism, TSH suppression).
• Symptoms of over- or under-treatment can mimic other conditions; always correlate with TSH levels.
• Weight loss should not be an indication for levothyroxine use in euthyroid individuals due to serious cardiac risks.

• Liothyronine (synthetic T3): Used less commonly, shorter half-life, more fluctuations in levels.
• Desiccated thyroid extract (e.g., Armour Thyroid, Nature-Throid): Natural thyroid hormone from porcine glands, contains both T4 and T3. Dosing can be less precise due to variable T4/T3 ratios.
• Liotrix (combination of T4 and T3 in a fixed ratio, e.g., Thyrolar): Less commonly used.

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. If you have any questions or concerns about your 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 medical attention. When seeking help, be prepared to provide information about what was taken, the amount, and the time it occurred.