Several thyroid medications have been recalled in recent years, most notably NP Thyroid, Nature-Throid, WP Thyroid, and Tirosint-SOL. The recalls share a common thread: the tablets or solutions contained too much or too little of the active thyroid hormone, meaning patients weren’t getting the dose printed on the label.
NP Thyroid by Acella Pharmaceuticals
Acella Pharmaceuticals issued a voluntary nationwide recall of certain lots of NP Thyroid (thyroid tablets, USP) due to super potency, meaning the pills contained more thyroid hormone than labeled. The recall covered multiple lots across the 30 mg, 60 mg, and 90 mg strengths. This recall has since been completed and terminated by the FDA.
Super potency is a serious problem with thyroid medication. Too much thyroid hormone can cause rapid heartbeat, chest pain, tremors, excessive sweating, and in severe cases, a life-threatening condition called thyrotoxicosis. For patients who had been taking affected lots, the risk was essentially an unintended overdose of thyroid hormone with every pill.
Nature-Throid and WP Thyroid by RLC Labs
RLC Labs recalled all lots of both Nature-Throid and WP Thyroid with current expiration dates due to sub potency. Testing showed these products may have contained as little as 87% of the labeled amount of T3 or T4, the two thyroid hormones your body needs. That 13% shortfall is significant for a medication with a narrow therapeutic window, where even small dose changes can shift how you feel and how your thyroid levels test on bloodwork.
Both Nature-Throid and WP Thyroid are desiccated (animal-derived) thyroid products. The FDA has raised broader concerns about this category of medications, noting that tablets made from the same manufacturing batches may not always deliver consistent thyroid hormone levels. Animal-derived thyroid medications also carry an increased risk of impurities due to the source tissue and manufacturing process. Many of these products have never gone through the FDA’s formal approval process for safety, purity, and potency.
Tirosint-SOL by IBSA Pharma
In January 2023, IBSA Pharma issued a voluntary nationwide recall of select lots of Tirosint-SOL, which is a levothyroxine sodium oral solution. The reason was subpotency, the same core issue as the Nature-Throid recall. This recall applied only to the liquid solution form. Tirosint capsules were not affected.
Why Potency Problems Are Common With Thyroid Drugs
Thyroid hormones are dosed in micrograms, not milligrams, which means even tiny manufacturing inconsistencies can throw off the ratio of what’s on the label versus what’s in the pill. Levothyroxine (T4) is also sensitive to heat, moisture, and light, so storage and stability during shelf life matter more than they do for many other medications.
For animal-derived products like NP Thyroid, Nature-Throid, and WP Thyroid, there’s an additional layer of variability. The raw material comes from pig thyroid glands, and the natural ratio of T3 to T4 in those glands isn’t perfectly uniform. That makes consistent dosing harder to achieve at scale, and it’s a key reason the FDA has flagged the entire category for quality concerns.
What Subpotent Thyroid Medication Feels Like
If you’ve been taking a thyroid medication that turned out to be subpotent, you may have experienced a return of hypothyroid symptoms without any obvious explanation. The most common signs include fatigue, weight gain, feeling unusually cold, joint and muscle pain, dry skin, thinning hair, and depression. Some people also notice heavier or irregular periods, or a slower-than-normal heart rate. These symptoms can creep in gradually, making it easy to assume something else is going on before the recall announcement connects the dots.
Super potent medication causes the opposite set of problems: anxiety, rapid heart rate, weight loss, tremors, and difficulty sleeping. If your symptoms suddenly shifted in either direction without a change in your prescribed dose, a potency issue with your medication is one possible explanation.
How to Check if Your Medication Is Affected
Every recall notice from the FDA lists the specific lot numbers and expiration dates of affected products. Your lot number is printed on the medication bottle or box, typically near the expiration date. You can cross-reference it against the FDA’s recall page for each product.
If you find your lot number on a recall list, don’t stop taking your medication abruptly. Suddenly going without thyroid hormone replacement can cause a sharp decline in thyroid levels. Contact your pharmacy or prescriber to get a replacement from an unaffected lot or switch to an alternative product. Your prescriber will likely want to recheck your thyroid levels with a blood test once you’ve been on a consistent, unaffected supply for several weeks.
The FDA maintains a searchable database of all active and completed drug recalls at fda.gov under “Recalls, Market Withdrawals, & Safety Alerts.” Bookmarking that page is the fastest way to stay current if you take any thyroid medication long term.