What is levothyroxine?
Levothyroxine is a synthetic form of thyroxine (T4), the main hormone produced by the thyroid. It's the standard treatment for hypothyroidism and is taken as a daily tablet, usually first thing in the morning on an empty stomach.
It replaces the hormone your thyroid can no longer produce in sufficient quantities, bringing your metabolism and other body functions back to normal. For most people, it's a lifelong treatment, but it's very effective and well-tolerated.
Getting the dose right
Finding the right dose can take a few months. Your GP will arrange blood tests (TSH and sometimes free T4) 6–8 weeks after starting or changing the dose, and adjust as needed until your levels are optimal.
Factors that can affect your dose include weight changes, pregnancy, age, and other medications. Your dose may need to be increased during pregnancy, which is why thyroid monitoring is important for women planning to conceive.
Tips for taking it correctly
Take levothyroxine on an empty stomach, at least 30 minutes before food or coffee. Certain foods and supplements can interfere with absorption — calcium, iron, and some antacids should be taken at least 2 hours apart from your thyroid medication.
Consistency matters. Take it at the same time each day, and don't skip doses. If you miss a dose, take it as soon as you remember — but don't double up. Your GP will monitor your levels regularly to ensure your dose is still right for you.
Related condition
Thyroid health →References & sources
- 1.Hypothyroidism — healthdirect
- 2.Thyroid gland — healthdirect
- 3.Thyroid gland — Better Health Channel
This content is general information and not a substitute for individual medical advice. Please consult a GP for your personal situation.
Ready to speak with a GP?
Book a private telehealth consult with an AHPRA-registered Australian GP.