Levothyroxine 0.175mg (175mcg) Tabs

Levothyroxine (L-thyroxine) is a synthetic form of thyroxine (T4), a hormone naturally produced by the thyroid gland. T4 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, fat, and carbohydrate metabolism, and influencing growth and development.

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 changes
Diarrhea, stomach cramps, or vomiting
Mood changes, such as feeling irritable, nervous, excitable, anxious, or restless
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 within the first few months of treatment)

Reporting Side Effects

This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, 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.

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

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. This will help prevent potential interactions and ensure the safe use of this medication with your other treatments and health conditions.

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 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. 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 using 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 developing weak bones (osteoporosis), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk of osteoporosis.

This medication may also affect fertility, potentially leading to difficulties in getting pregnant or fathering a child. If you plan to conceive, consult with your doctor before starting treatment.

Special Considerations

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

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 with you, considering both your health and the baby's well-being.

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 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, and your doctor will monitor your child's growth and development.

• Amiodarone (can cause hypo- or hyperthyroidism, alters T4/T3 conversion)
• Oral anticoagulants (e.g., Warfarin - levothyroxine may increase anticoagulant effect by increasing catabolism of vitamin K-dependent clotting factors)
• Ion exchange resins (e.g., Cholestyramine, Colestipol, Sevelamer, Patiromer - significantly decrease levothyroxine absorption; separate administration by at least 4 hours)
• Sucralfate (decreases levothyroxine absorption; separate administration by at least 4 hours)
• Proton pump inhibitors (PPIs) (e.g., Omeprazole, Lansoprazole - may decrease levothyroxine absorption due to increased gastric pH; monitor TSH)
• Antacids (e.g., Aluminum hydroxide, Calcium carbonate - decrease levothyroxine absorption; separate administration by at least 4 hours)
• Iron supplements (decrease levothyroxine absorption; separate administration by at least 4 hours)
• Calcium supplements (decrease levothyroxine absorption; separate administration by at least 4 hours)
• Tyrosine kinase inhibitors (e.g., Sunitinib, Imatinib - may increase TSH levels and require increased levothyroxine dose)
• Orlistat (may decrease levothyroxine absorption; separate administration by at least 4 hours)

• Estrogens (e.g., Oral contraceptives, HRT - increase TBG, potentially increasing levothyroxine requirements)
• Androgens (e.g., Testosterone - decrease TBG, potentially decreasing levothyroxine requirements)
• Glucocorticoids (e.g., Prednisone - may decrease TSH secretion and alter T4/T3 conversion)
• Beta-blockers (e.g., Propranolol - may inhibit peripheral conversion of T4 to T3)
• Antidiabetic agents (e.g., Insulin, Metformin - levothyroxine may increase blood glucose; monitor glucose levels)
• Digoxin (levothyroxine may decrease digoxin levels; monitor digoxin levels)
• Phenytoin, Carbamazepine, Rifampin, Phenobarbital (induce hepatic metabolism of thyroid hormones, potentially increasing levothyroxine requirements)
• Sertraline (may increase levothyroxine requirements, especially in patients on stable doses)
• Soy products (may decrease levothyroxine absorption; separate administration)
• Coffee (may decrease levothyroxine absorption; separate administration)

• Dietary fiber (may decrease absorption if taken concurrently)

• Fatigue
• Weight changes (gain or loss)
• Constipation or diarrhea
• Cold or heat intolerance
• Dry skin or hair loss
• Muscle aches or weakness
• Depression or anxiety
• Memory impairment
• Bradycardia or tachycardia
• Palpitations
• Tremor
• Nervousness
• Insomnia

Levothyroxine is the drug of choice for hypothyroidism during pregnancy. Thyroid hormone requirements typically increase during pregnancy (by 25-50% or more) due to increased TBG, placental deiodination, and fetal thyroid hormone needs. Close monitoring of TSH (every 4-6 weeks) and dose adjustments are crucial to maintain maternal euthyroidism, which is essential for fetal neurodevelopment.

Levothyroxine is considered safe during breastfeeding. Only small amounts are excreted into breast milk, and these amounts are not sufficient to cause adverse effects in the infant or affect infant thyroid function. It is compatible with breastfeeding.

Dosing is weight-based and higher per kilogram than in adults, especially in infants and young children, due to higher metabolic rates and rapid growth. Regular monitoring of TSH and Free T4 is essential to ensure proper growth and neurodevelopment. Adherence is critical for preventing irreversible cognitive impairment in congenital hypothyroidism.

Older patients, especially those with underlying cardiovascular disease, should be started on lower initial doses (e.g., 12.5-25 mcg/day) and titrated more slowly to avoid precipitating cardiac events. Monitor for symptoms of hyperthyroidism. TSH target ranges may be slightly higher in very elderly patients.

• Levothyroxine has a narrow therapeutic index; small dose changes can have significant effects on TSH.
• Consistency is key: Advise patients to take the medication at the same time each day, preferably in the morning on an empty stomach, 30-60 minutes before food or other medications.
• Avoid concurrent administration with calcium, iron, antacids, and certain other medications (separate by at least 4 hours).
• Patients should be advised not to switch between different generic or brand formulations without consulting their physician, as bioequivalence can vary, potentially requiring dose adjustments.
• Full therapeutic effect and TSH stabilization may take 4-6 weeks after a dose change.
• Symptoms of hypothyroidism may take several weeks or months to fully resolve after achieving euthyroidism.
• Educate patients on symptoms of both hypo- and hyperthyroidism to recognize potential under- or overtreatment.

• Liothyronine (synthetic T3 - Cytomel, Triostat; shorter half-life, more potent, higher risk of fluctuations)
• Desiccated thyroid extract (natural thyroid hormone from porcine glands, contains T4 and T3 - Armour Thyroid, Nature-Throid, NP Thyroid)

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 medication taken, the amount, and the time it occurred.