Euthyrox (levothyroxine) dosage is highly individualized. It depends on your age, weight, pregnancy status, how your thyroid is (hypothyroid vs. other conditions), and your lab results (TSH, free T4). A doctor must determine and monitor the exact dose. Here are general guidelines often used in adults, but you should follow your clinician’s instructions:
- Adults with overt hypothyroidism (new treatment)
- Starting often 25–50 mcg once daily if older or has heart disease; otherwise around 1.6 mcg/kg/day (roughly 75–125 mcg/day for many adults).
- If starting higher, doctors typically adjust every 4–6 weeks based on TSH/free T4.
- Healthy adult replacement (typical maintenance)
- Common maintenance around 100–125 mcg/day (varies by body size and labs).
- Elderly or with heart disease
- Start lower (25–50 mcg/day) and increase slowly, monitoring for heart symptoms.
- Pregnancy
- Usually requires an increase in dose soon after pregnancy is confirmed (often about +30% or more). Dose is adjusted guided by TSH and free T4 each 4 weeks in the first trimester, then every 6–8 weeks throughout pregnancy.
- Children (weight-based, needs pediatric dosing)
- Neonates: about 10–15 mcg/kg/day.
- Infants/children: dose is guided by weight and TSH, then adjusted regularly.
How to take it
- Take once daily in the morning on an empty stomach, at least 30–60 minutes before breakfast.
- Take with a full glass of water.
- Avoid taking it with meals or large amounts of calcium, iron, aluminum antacids, sucralfate, or bile acid sequestrants within a few hours (these can reduce absorption). If you need those, separate by about 4 hours.
- Do not switch brands or formulations without your doctor’s guidance.
Monitoring and safety
- After starting or changing the dose, your doctor will recheck TSH (and usually free T4) in about 4–8 weeks.
- Once stable, monitoring is typically every 6–12 months (more often if pregnant or changing doses).
- Signs of too much thyroid hormone: palpitations, anxiety, insomnia, weight loss, heat intolerance, sweating; risks include heart rhythm problems and bone loss in some people.
- Signs of too little: fatigue, weight gain, cold intolerance, constipation, dry skin.
If you’d like, tell me:
- Your age and weight
- Whether you’re pregnant or breastfeeding
- Your reason for Euthyrox (hypothyroidism, hashimoto’s, thyroid surgery, etc.)
- Your current dose or recent lab results (TSH/free T4)
With those, I can give more targeted general ranges and what your doctor might consider. But please rely on your doctor’s exact prescription.