From the FDA Drug Label
Gastric acidity is an essential requirement for adequate absorption of levothyroxine. Sucralfate, antacids and proton pump inhibitors may cause hypochlorhydria, affect intragastric pH, and reduce levothyroxine absorption. Monitor patients appropriately.
The use of proton pump inhibitors with levothyroxine may still cause a problem with absorption, as gastric acidity is essential for adequate absorption of levothyroxine. It is recommended to monitor patients appropriately when taking these medications together 1, 1.
- Key points:
- Proton pump inhibitors may reduce levothyroxine absorption
- Gastric acidity is necessary for adequate levothyroxine absorption
- Monitoring of patients is recommended when taking these medications together
From the Research
Taking a proton pump inhibitor (PPI) regularly along with levothyroxine can still cause absorption problems, but the most recent and highest quality study suggests that a novel liquid formulation of levothyroxine may not be affected by PPIs 2. To minimize this interaction, you should take levothyroxine on an empty stomach at least 30-60 minutes before your PPI medication (such as omeprazole, pantoprazole, or esomeprazole). However, the latest study from 2024 indicates that the bioavailability of a liquid formulation of levothyroxine is not affected by coadministration of a representative PPI, given simultaneously or staggered by about 12 hours, compared to administration of LT4 solution alone 2. Some key points to consider:
- PPIs reduce stomach acid, which is needed for proper levothyroxine absorption.
- Even with regular use of PPIs, this interaction doesn't diminish over time.
- If you're on both medications long-term, your doctor may need to monitor your thyroid function tests more frequently and potentially adjust your levothyroxine dose to compensate for reduced absorption.
- Alternative formulations of levothyroxine (like liquid or gel capsules) might be less affected by this interaction, as suggested by the study from 2024 2.
- Other studies have shown that concomitant use of LT4 and PPI can increase TSH levels, but the study from 2024 provides more recent and higher quality evidence on this topic 3, 4, 5.