⚕️ Full Prescribing Information
For complete safety information, warnings, and dosage guidelines:
View FDA Label (PDF) →📋 Overview
Synthroid (levothyroxine) is a synthetic thyroid hormone identical to the hormone produced by the thyroid gland. It replaces hormone when the thyroid cannot produce enough.
How It Works
Synthroid replaces or supplements the natural thyroid hormone thyroxine (T4), which regulates metabolism, energy levels, and many body functions.
✓ FDA Approved Uses
- Hypothyroidism treatment
- Pituitary TSH suppression
- Thyroid suppression test
🧪 Required Lab Monitoring
Your healthcare provider will order these tests to monitor your treatment:
Free T4
If TSH abnormal or symptoms persist
Every 6-8 weeks until stable, then every 6-12 months
Need to book these tests?
Order Tests Online →⚡ Common Side Effects
Contact your doctor if these persist or worsen:
- Hair loss (usually temporary)
- Weight changes
- Insomnia
- Tremors
- Headache
- Sweating
🚨 Serious Side Effects
Seek immediate medical attention if you experience:
- Chest pain or irregular heartbeat
- Shortness of breath
- Seizures
- Severe allergic reaction
⚠️ Do Not Use If
- Untreated adrenal insufficiency
- Untreated thyrotoxicosis
- Acute myocardial infarction
- Hypersensitivity to levothyroxine
📢 Important Warnings
- Take on empty stomach 30-60 minutes before breakfast
- Do not take with calcium or iron supplements within 4 hours
- Regular TSH monitoring required