Levonthyroxine 50mcg

Product Name: Levothyroxine Sodium 50 micrograms

Common Brand Names: Eltroxin, Euthyrox, Synthroid (varies by country)
Prescription Status: Prescription required

What It Is

Levothyroxine is a synthetic form of thyroxine (T4)—a hormone normally produced by the thyroid gland. It is used to replace or supplement natural thyroid hormone in the body.

Indications (Uses)

• Hypothyroidism (underactive thyroid)

• Post-thyroidectomy hormone replacement

• Goiter suppression

• Management of thyroid cancer (adjunctive)

• Sometimes used in congenital hypothyroidism in infants/children

Dosage & Administration

• Typical adult starting dose for mild hypothyroidism: 25–50 mcg once daily

• For full replacement: up to 1.6 mcg/kg/day (adjusted based on age, weight, TSH levels)

• Take on an empty stomach, ideally 30–60 minutes before breakfast

• Avoid taking with calcium, iron, soy, antacids, or coffee within 4 hours—these reduce absorption

• Dose must be individualized based on TSH and free T4 levels. Follow your doctor’s instructions strictly.

Onset of Action

• Full therapeutic effect may take 2–4 weeks

• Blood levels stabilize slowly, so dose changes are usually made at 6-week intervals

Precautions & Interactions

• Regular blood tests (TSH, T4) are essential to monitor effectiveness and avoid over/underdosing

• Use cautiously in patients with:

  • Heart disease or angina

  • Adrenal insufficiency

  • Osteoporosis (high doses may worsen bone loss)

Drug interactions:

• Reduces effect of insulin and antidiabetics

• Reduced absorption with iron, calcium, antacids, cholestyramine

• Certain anti-seizure and psychiatric drugs may lower thyroxine levels

Possible Side Effects (Usually due to overdosage)

Signs of overreplacement (hyperthyroidism):

• Palpitations

• Weight loss

• Insomnia

• Anxiety, tremors

• Sweating

• Increased appetite

• Menstrual irregularities

Rare but serious:

• Chest pain or irregular heartbeat

• Seizures

• Fractures from long-term high-dose use

Pregnancy & Breastfeeding

• Safe in pregnancy – dose often needs to be increased

• Safe while breastfeeding – minimal secretion in breast milk

Storage Instructions

• Store at room temperature

• Protect from moisture and light

• Keep in original packaging until use