Product Description

Thyroxine Sodium Tablets IP 100 mcg (levothyroxine sodium) is a synthetic form of thyroxine (T₄), the primary hormone produced by the thyroid gland. It is used to treat hypothyroidism (underactive thyroid), a condition where the gland produces insufficient thyroid hormones, leading to slowed metabolism, fatigue, weight gain, constipation, depression, and other symptoms. It also manages goiter (thyroid enlargement) and thyroid hormone replacement in cases of deficiency, such as post-thyroidectomy or congenital hypothyroidism. Restoring normal hormone levels helps regulate metabolism, energy production, and overall bodily functions.

Uses

• Replacement therapy for primary hypothyroidism (e.g., Hashimoto's thyroiditis, post-surgical, or radioactive iodine ablation)

• Management of secondary or tertiary hypothyroidism (pituitary or hypothalamic issues)

• Treatment of congenital hypothyroidism in infants and children

• Suppression of thyroid-stimulating hormone (TSH) in thyroid cancer or nodules

• Adjunct management of goiter to normalize hormone levels and reduce gland size

How it works

Thyroxine Sodium Tablets IP 100 mcg provide hormone replacement therapy with synthetic T₄, which is bioidentical to the natural hormone.

• Absorption and Conversion: After oral ingestion, it is absorbed primarily in the small intestine and enters the bloodstream. It is then converted peripherally (mainly in the liver, kidneys, and muscles) to the more active triiodothyronine via deiodinase enzymes (outer-ring deiodination). About 80% of it is produced this way, with the rest directly secreted by the thyroid.

• Cellular Action: enters cells and binds to nuclear thyroid hormone receptors, forming a complex that interacts with DNA to regulate gene transcription. This influences protein synthesis and metabolic processes.

• Metabolic Regulation: By normalizing thyroid hormone levels, it restores euthyroid (normal) function, accelerating basal metabolic rate, enhancing energy production, and reversing hypothyroid symptoms. Full effects may take 4–6 weeks due to the hormone's long half-life (about 7 days).

Regular TSH monitoring ensures dose optimization.

Benefits

• Restores normal metabolism, alleviating fatigue, lethargy, and low energy.

• Aids weight management by correcting slowed metabolism and reducing unexplained weight gain.

• Improves cognitive function, mood, memory, and concentration affected by hypothyroidism.

• Relieves physical symptoms such as dry skin, hair loss, muscle aches, constipation, and cold intolerance.

• Supports cardiovascular health by normalizing heart rate and cholesterol levels.

• In children, it promotes normal growth and development; in adults, it prevents complications like myxedema coma.

How to use

Taking Thyroxine Sodium 100 mcg requires a specific routine to ensure proper absorption and effectiveness. Because food, supplements, and other medications can interfere with its absorption, the timing of your dose is crucial. Take the tablet once daily on an empty stomach in the morning, at least 30 to 60 minutes before breakfast for optimal absorption. Swallow the tablet whole with a full glass of water. It should not be crushed, chewed, or broken unless explicitly instructed by a doctor. Some studies suggest that taking it at night, at least three to four hours after your last meal, can also be effective and may be an option if your mornings are too rushed.

Side Effects

Side effects typically indicate incorrect dosing (too high mimicking hyperthyroidism; too low prolonging hypothyroidism) and require TSH adjustment:

Overdose (Hyperthyroid-like Symptoms):

• Cardiovascular: palpitations, rapid/irregular heartbeat, chest pain, increased blood pressure

• Neurological: headache, nervousness, irritability, tremors, insomnia

• Gastrointestinal: increased appetite, weight loss, diarrhea, abdominal cramps

• Other: heat intolerance, excessive sweating, muscle weakness, menstrual irregularities

Underdose (Persistent Hypothyroid Symptoms):

• Fatigue, weight gain, constipation, cold sensitivity

Rare allergic reactions: rash, swelling. Seek immediate care for severe symptoms like chest pain or severe headache.

Safety Advice. 

• Dosage must be tailored via regular TSH/free blood tests (every 6–8 weeks initially, then annually once stable).

• Not for weight loss in euthyroid individuals—can cause life-threatening thyrotoxicosis.

• Inform your doctor if pregnant (dose may increase by 25–50% due to higher demand), breastfeeding (safe, as minimal transfer to milk), or planning surgery (may need temporary adjustment).

• Use caution in cardiovascular disease, adrenal insufficiency (treat concurrently), or elderly patients (start low to avoid cardiac strain).

• Avoid self-adjusting doses; abrupt cessation can worsen hypothyroidism.

• Interactions: Separate from iron/calcium supplements, antacids, or proton pump inhibitors by 4 hours. Inform doctor of all medications (e.g., estrogens, rifampin may alter requirements).

Storage Conditions

Store at a temperature below 86°F (30 °C). Protect from light and moisture.

FAQs

What is Thyroxine Sodium 100 mcg used for? 

It treats hypothyroidism by replacing deficient thyroid hormone, regulating metabolism, and relieving symptoms like fatigue, weight gain, and depression. Also used for goiter and thyroid suppression in cancer.

How does Thyroxine Sodium 100 mcg work? 

It contains levothyroxine, a synthetic version of the thyroid hormone T₄. The body converts this into the active hormone T₃, which then regulates your body's metabolism. 

Can this be used for weight loss?

No, this medication is not for weight loss. Taking thyroid hormone can cause serious and life-threatening side effects in individuals with normal thyroid function. 

How long does it take to work?

Although the medication starts working immediately, it may take several weeks to notice a significant improvement in symptoms as the body adjusts and hormone levels stabilize. 

What should be done if a dose is missed?

If a dose is missed, take it as soon as remembered. However, if the next scheduled dose is near, skip the missed dose and continue the regular dosing schedule. A double dose should not be taken. 

Can the medication be stopped once one feels better?

No, you should not stop taking Thyroxine without consulting a doctor. Hypothyroidism is often a lifelong condition, and stopping the medication can cause symptoms to return and lead to other health complications. 

What are the common side effects?

Side effects often indicate that dosage adjustments are needed. Common side effects include: Increased appetite, hair loss (often temporary), Headache, Nervousness or irritability, Trouble sleeping, Rapid or irregular heartbeat (palpitations), increased sweating, Diarrhea 

Does it have any interactions with other medicines or food?

Yes, several substances can interfere with the absorption of Thyroxine Sodium. Medicines: Antacids, iron and calcium supplements, certain cholesterol-lowering medications, and some antidepressants. Separate the dose by at least four hours. Foods: Soy products, walnuts, cottonseed meal, and high-fiber foods can all decrease absorption. Also, wait at least 30 to 60 minutes after taking the dose before having breakfast or a caffeinated drink. 

Is it safe for pregnant or breastfeeding women?

Thyroxine Sodium is generally considered safe during pregnancy and breastfeeding, but your doctor may need to adjust the dosage. Regular monitoring of thyroid levels is essential for both the mother's and the baby's health.