Levothyroxine 0.150mg (150mcg) Caps

Levothyroxine (T4) is a synthetic form of the natural thyroid hormone, thyroxine. It is converted to its active metabolite, liothyronine (T3), in peripheral tissues. T3 and T4 act on thyroid hormone receptors in the cell nucleus, regulating gene expression and controlling numerous metabolic processes, including protein, carbohydrate, and lipid metabolism, and influencing growth and development.

Serious Side Effects: Seek Medical Help Right Away

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 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 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 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. 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 symptoms that bother you or do not go away, contact your doctor:

* Hair loss (usually temporary and resolves on its own within the first few months of treatment)

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

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, provide your doctor and pharmacist with a comprehensive list of all the medications you are taking, including:
Prescription medications
Over-the-counter (OTC) medications
Natural products
* Vitamins

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. 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 you 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 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 you and your baby.

Pediatric Patients

If you are giving this medication to a child and their weight changes, 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, so be sure to discuss this with your doctor.

• Amiodarone (can cause hypo- or hyperthyroidism, affecting levothyroxine dose)
• Warfarin (levothyroxine can enhance anticoagulant effect, requiring warfarin dose reduction)
• Antidiabetic agents (levothyroxine can increase blood glucose, requiring antidiabetic dose adjustment)
• Cholestyramine, Colestipol, Sevelamer, Sucralfate (significantly decrease levothyroxine absorption)
• Iron supplements, Calcium supplements, Antacids (aluminum, magnesium, calcium salts) (decrease levothyroxine absorption)
• Proton pump inhibitors (PPIs) and H2 blockers (may reduce gastric acidity, impairing levothyroxine absorption)

• Estrogens (increase TBG, potentially increasing levothyroxine requirement)
• Androgens (decrease TBG, potentially decreasing levothyroxine requirement)
• Phenytoin, Carbamazepine, Rifampin, Phenobarbital (induce hepatic metabolism of thyroid hormones, increasing levothyroxine requirement)
• Beta-blockers (may reduce peripheral conversion of T4 to T3)
• Digoxin (levothyroxine may decrease digoxin levels)
• SSRIs (may affect thyroid function tests, requiring monitoring)
• Soy products (may decrease levothyroxine absorption)

• Dietary fiber (may decrease absorption if taken concurrently)

• Symptoms of hypothyroidism (e.g., fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, depression, bradycardia)
• Symptoms of hyperthyroidism (e.g., palpitations, tachycardia, nervousness, tremor, weight loss, heat intolerance, diarrhea, insomnia, anxiety)

Levothyroxine 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. Dose adjustments are typically needed and should be monitored closely.

Levothyroxine is considered safe during breastfeeding. Only small amounts are excreted into breast milk, which are not expected to cause adverse effects in the infant.

Crucial for normal growth and development. Dosing is weight-based and higher per kg than in adults, especially in infants. Regular monitoring of TSH and FT4 is essential to ensure proper brain development and growth. Underdosing can lead to irreversible cognitive impairment.

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 risk of cardiac adverse events. Dose titration should be slower and more cautious. TSH target range may be slightly higher (e.g., 4-6 mIU/L) in very elderly patients without specific indications for lower TSH.

• Always take levothyroxine on an empty stomach, 30-60 minutes before breakfast, with water, and separate from other medications/supplements by at least 4 hours.
• Consistency is key: take at the same time every day.
• The long half-life means that dose adjustments take 4-6 weeks to see full effect on TSH levels.
• Patients should be educated on symptoms of both hypo- and hyperthyroidism to report to their physician.
• Brand-name levothyroxine products (Synthroid, Levoxyl, Unithroid, Tirosint) are generally considered bioequivalent, but some clinicians and patients prefer to stick with one brand due to slight differences in excipients that could theoretically affect absorption in sensitive individuals. Switching brands should be done with caution and TSH re-monitoring.
• Capsule formulations (Tirosint) may offer more consistent absorption for some patients, especially those with gastrointestinal issues or taking interacting medications, as they contain fewer excipients.

• Liothyronine (T3, Cytomel): Synthetic T3, shorter half-life, faster onset, used in specific cases (e.g., myxedema coma, thyroid cancer withdrawal).
• Desiccated Thyroid Extract (DTE, e.g., Armour Thyroid, Nature-Throid): Natural thyroid hormone from porcine thyroid glands, contains both T4 and T3. Dosing can be less precise due to variable T4/T3 ratios and potency.
• Levothyroxine/Liothyronine combination products (e.g., Thyrolar): Synthetic T4/T3 combination, less commonly used than levothyroxine alone.

If your symptoms or health issues persist or worsen, it's 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 be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to 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 details about the medication taken, the amount, and the time it happened.