When should I take Euthyroxin (levothyroxine)?

From the Guidelines

Euthyroxin (levothyroxine) should be taken once daily in the morning, on an empty stomach, 30-60 minutes before breakfast. This timing is crucial for optimal absorption, as food and other substances can interfere with the absorption of levothyroxine 1. Taking it first thing in the morning ensures better absorption and maintains stable blood levels of the hormone throughout the day.

• The standard starting dose varies based on age, weight, and severity of thyroid dysfunction, with a dose of approximately 1.6 mcg/kg/d for patients without risk factors, and a lower starting dose of 25-50 mg for those older than age 70 years and/or frail patients with multiple comorbidities, including cardiac disease 1.
• It is essential to take Euthyroxin with a full glass of water and wait before consuming food, other medications, or supplements, especially those containing calcium or iron.
• Consistent timing is vital, and if you miss a dose, take it as soon as you remember that day, but if it's almost time for the next day's dose, skip the missed dose and continue your regular schedule.
• Never change your dose without medical guidance, as proper thyroid hormone levels are crucial for many bodily functions, and elevated TSH can be seen in the recovery phase of thyroiditis, which may require monitoring before treating 1.

From the Research

Euthyroxin Administration Timing

The optimal timing for taking Euthyroxin (levothyroxine) is a topic of interest for patients with hypothyroidism. Several studies have investigated the effects of morning versus evening administration of levothyroxine on thyroid hormone levels and overall efficacy.

• A study published in 2007 found that taking levothyroxine at bedtime resulted in higher thyroid hormone concentrations and lower TSH concentrations compared to taking it in the morning 2.
• A 2022 study evaluated the bioavailability of a novel levothyroxine solution taken 15 minutes before a high-fat, high-calorie meal and found no significant difference in pharmacokinetic properties compared to taking it 30 minutes before the meal 3.
• However, a 2015 study found that changing the levothyroxine administration time from before breakfast to before dinner resulted in a decrease in therapeutic efficacy, with increased TSH levels and decreased T4 levels 4.
• A randomized double-blind crossover trial published in 2010 found that levothyroxine intake at bedtime significantly improved thyroid hormone levels, with decreased TSH levels and increased free thyroxine and total triiodothyronine levels 5.
• A 2023 study investigated the effect of morning versus night-time administration of proton pump inhibitor (pantoprazole) on thyroid function test in levothyroxine-treated primary hypothyroidism and found that concomitant use of pantoprazole led to significant elevation in serum TSH, irrespective of timing of pantoprazole intake 6.

Key Findings

• Taking levothyroxine at bedtime may result in better gastrointestinal uptake and improved thyroid hormone levels 2, 5.
• The timing of levothyroxine administration may affect its efficacy, with some studies suggesting that bedtime administration may be more effective 2, 5.
• However, other studies have found that changing the administration time from morning to evening may decrease therapeutic efficacy 4.
• Concomitant use of certain medications, such as proton pump inhibitors, may affect thyroid function tests and levothyroxine efficacy 6.