Levothyroxine

Generic Name: levothyroxine sodium

Thyroid HormonesPrescription Required

Brand Names:

Synthroid, Levoxyl, Tirosint, Unithroid

Levothyroxine is a synthetic form of the thyroid hormone thyroxine (T4) used to treat hypothyroidism.

Overview

Levothyroxine is a synthetic form of the thyroid hormone thyroxine (T4) used to treat hypothyroidism.

Uses

Hypothyroidism, thyroid hormone replacement after thyroidectomy, TSH suppression in thyroid cancer.

Dosage

Adults: Starting dose 25–50 mcg daily, full replacement averages 1.6 mcg/kg/day.

Side Effects

When properly dosed, side effects are uncommon. Over-replacement: Rapid heartbeat, tremor, anxiety.

Interactions

Calcium, iron, antacids reduce absorption — separate by 4 hours.

Warnings

Not for weight loss. Requires regular TSH monitoring.

Pregnancy

Category A — Safe and important to continue during pregnancy.

Storage

Store at room temperature. Protect from light and moisture.

Frequently Asked Questions

What is Levothyroxine used for?

Hypothyroidism, thyroid hormone replacement after thyroidectomy, TSH suppression in thyroid cancer.

What are the side effects of Levothyroxine?

When properly dosed, side effects are uncommon. Over-replacement: Rapid heartbeat, tremor, anxiety.

Can I take Levothyroxine during pregnancy?

Category A — Safe and important to continue during pregnancy.

What are the important warnings for Levothyroxine?

Not for weight loss. Requires regular TSH monitoring.

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Medical Disclaimer

This drug information is for educational purposes only and should not replace professional medical advice. Drug information is sourced from the FDA National Drug Code Directory and Structured Product Labeling. Always consult with a healthcare provider before starting, stopping, or changing any medication.