Levothyroxine (Thyronorm, Eltroxin): uses, dose & side effects
Written & medically reviewed by Dr. Sanjay Anbu, MBBS· Last reviewed
Levothyroxine replaces the thyroid hormone missing in an underactive thyroid (hypothyroidism). Taken correctly it restores normal energy and metabolism, and is usually needed long term.
Typical dose — general reference only, NOT a prescription
Measure
Range
Category
Prescription
Adult dose
About 1.6 mcg/kg once daily on an empty stomach (typically 50–150 mcg); adjusted by blood tests
Child (paediatric) dose
Weight-based (higher per kg than adults) — set by a doctor
What it is used for
Underactive thyroid (hypothyroidism)
After thyroid surgery or radioactive iodine
Certain thyroid conditions in pregnancy
Common brand names
India: Thyronorm, Eltroxin, Thyrox
Worldwide: Synthroid, Euthyrox, Levoxyl
Common side effects
Few if the dose is right
Too much: palpitations, weight loss, shakiness
Too little: tiredness, weight gain, feeling cold
Before taking it — precautions
Take on an empty stomach, 30–60 min before breakfast
Separate from calcium, iron and antacids by a few hours
Stay on the same brand
When to see a doctor urgently
Chest pain or racing/irregular heartbeat (over-replacement)
Symptoms returning strongly (under-treatment)
Doses are a general reference, not a prescription. Doses shown are typical adult/paediatric references and vary with age, weight, kidney/liver function and the exact product. Paediatric doses are usually weight-based and must be set by a doctor. MedDroid cannot prescribe — always confirm levothyroxine and your dose with a doctor or pharmacist and the leaflet inside the pack.
Frequently asked questions
Why on an empty stomach?
Food, coffee and some minerals reduce absorption, so take it 30–60 minutes before breakfast for steady levels.
Do I need it for life?
Usually yes — the thyroid cannot make enough on its own; the dose is fine-tuned with blood tests.
Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.