Popular thyroid drugs recalled because they're weaker than expected

Only weeks after multiple lots of thyroid medication were recalled over being too potent, the FDA is highlighting a new recall covering nearly 500 lots of popular thyroid meds — this time because they're not potent enough. According to the recall notice, random testing of multiple lots found that the active amount of thyroid hormone in the medication was lower than expected, substantially so in some cases.READ: Popular thyroid drug recalled because it's 'super potent' says FDA

The latest recall was announced on Thursday, September 3; it comes from RLC Labs, which voluntarily initiated the recall after half a dozen lots of WP Thyroid and Nature-Throid tested below their expected potency levels.

Both of these medications feature the T3 and T4 hormones, unlike commonly prescribed Synthroid and Euthyroid, which only contain T4. According to the recall notice, the randomly tested drug lots of these two medications revealed that they don't contain as much T3 and T4 as they're supposed to.

In at least one case, a lot of the medication tested as low as 87-percent of the intended amounts of these hormones. By taking drugs that have too little hormones, thyroid patients are at risk of the return of symptoms, including feeling cold, developing dry skin, hair loss, mental health problems, weight gain, puffy face, and more.

It takes time to build one's hormone levels back to where they're supposed to be, making it particularly important to avoid taking sub-ideal doses. The recall impacts bottles featuring between 30 and 1,000 pills each. Pictures of the recalled pills, as well as potency, packaging, and lot numbers, can be found on the FDA's website here.