Levothyroxine Dosage Guide

Typical Levothyroxine Dosages

Levothyroxine dosage is highly individualized and depends on age, weight, the severity of hypothyroidism, other medical conditions, and the presence of heart disease. Doses are measured in micrograms (mcg) and may be adjusted over time based on thyroid function tests (TSH, T4).

• Adults (under 50 years old): Typically started at 50–100 mcg once daily. May be increased gradually every 4–6 weeks.
• Adults over 50 or with heart disease: Often started at a lower dose (25 mcg daily) and increased slowly.
• Children: Doses are based on weight and age; your doctor will calculate the correct amount.
• Pregnancy: Requirements often increase; careful monitoring is essential.

Never adjust your dose without consulting your healthcare provider. Taking too much levothyroxine can cause symptoms of hyperthyroidism, while too little can leave you with hypothyroid symptoms.

How to Take Levothyroxine Correctly

1. Take levothyroxine once daily, preferably in the morning on an empty stomach.
2. Swallow the tablet whole with a full glass of water.
3. Wait at least 30–60 minutes before eating, drinking coffee, or taking other medications.
4. Take it at the same time every day to maintain even hormone levels.
5. If you miss a dose, take it as soon as you remember unless it is almost time for your next dose. Do not take two doses at once.

Factors That May Affect Your Dose

• Weight changes – significant weight gain or loss may require dose adjustment.
• Age – older adults may need lower starting doses.
• Other medical conditions – heart disease, diabetes, adrenal insufficiency, etc.
• Medications – certain drugs can alter how levothyroxine works.
• Pregnancy and breastfeeding – thyroid hormone needs may change.
• Switching brands or generics – even small differences can affect levels; your doctor may need to retest.

Monitoring and Follow-Up

Regular blood tests are necessary to ensure your dose is correct. Typically, TSH is checked 6–8 weeks after starting or changing the dose, then every 6–12 months once stable. Always attend follow-up appointments and report any new symptoms.