Levothyroxine is typically recommended to be taken on an empty stomach, ideally 30 to 60 minutes before breakfast, to enhance its absorption and bioavailability
. This recommendation is based on the understanding that food ingestion can significantly affect the oral absorption of many drugs, including levothyroxine
Impact of food on levothyroxine absorption
- Studies have shown that the absorption of levothyroxine, when taken as a tablet, is significantly decreased with concomitant food ingestion
- A study found that the serum thyrotropin (TSH) concentration was significantly higher when levothyroxine was taken with breakfast compared to when it was taken in a fasting state
- Another study found that levothyroxine administration with breakfast could be an alternative regimen for patients who have adherence difficulties due to the need for delaying intake. However, this regimen is more likely to cause variability in TSH levels, suggesting that patients should be followed more closely
Levothyroxine administration recommendations
- The American Association of Clinical Endocrinologists and the American Thyroid Association (AACE/ATA) 2012 guidelines recommend advising patients to take levothyroxine with water consistently 30–60 minutes before breakfast, or at bedtime, 4 hours after the last meal
- A novel levothyroxine solution has been shown to result in similar bioavailability whether taken 30 or just 15 minutes before a high-fat, high-calorie meal
In conclusion, taking levothyroxine on an empty stomach is generally recommended to enhance its absorption and bioavailability. However, for patients who have difficulty adhering to the fasting requirement, taking levothyroxine with breakfast or at bedtime, 4 hours after the last meal, could be considered, with the understanding that this may lead to more variability in TSH levels and may require closer monitoring.