Do NSAIDs Affect Your Thyroid Levels?

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and aspirin, are a class of drugs that are commonly used to relieve pain and inflammation and reduce fever.

When taken orally as a pill or tablet, NSAIDs produce systemic (whole body) effects. As such, it's natural to wonder whether NSAIDs target your thyroid gland along with all the other tissues and organs in your body. While it is possible that NSAIDs may affect your thyroid, scientific evidence in favor of this is scant.

This article presents the research on whether or not NSAIDs influence thyroid function. It also discusses what this research means for you.

General Side Effects of NSAIDs

NSAIDs reduce pain and inflammation in the body by blocking enzymes called cyclooxygenases, which are involved in the formation of platelets (blood cells that help blood clot).

When taken orally, NSAIDs affect the cardiovascular, gastrointestinal (GI), renal (kidneys), and respiratory systems. They are associated with an increased risk of bleeding in the GI tract, myocardial infarction (heart attack), and stroke, particularly in people ages 65 and older.

Most people tolerate NSAIDs well, but side effects—such as stomach irritation and headaches—can occur. In fact, some people should not take NSAIDs at all, like those with kidney disease, heart failure, or cirrhosis (a late-stage liver disease ).

NSAIDs and Your Thyroid Function

The list of main concerns related to NSAID use does not include any threats to thyroid function. However, there are two studies that suggest NSAIDs may influence it.

In one study published in the journal Life Sciences, researchers used computer and chemistry methods (not human participants) to analyze how three commonly prescribed NSAIDs interact with thyroid hormone receptors in the body. The NSAIDs studied were Voltaren (diclofenac), Aleve (naproxen), and Celebrex (celecoxib).

The researchers found that Voltaren and Celebrex (but not Aleve) did bind to thyroid hormone receptors. In theory, this could impair thyroid hormone signaling, in which thyroid hormones stimulate actions in other body parts and systems. That said, it's difficult to translate this finding to actual people.

Another study, published in The Journal of Clinical Endocrinology & Metabolism (JCEM), was done on humans. The study included just 25 healthy individuals. Each was asked to take one of the following NSAIDs as part of a single-dose trial and/or a one-week trial:

• Over-the-counter NSAIDs: Aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn, Anaprox)
• Prescription NSAIDs: Salsalate (Disalcid, Salflex), meclofenamate (Meclomen), indomethacin (Indocin, Tivorbex)

Researchers analyzed the effect that NSAIDs had on three different hormones: free thyroxine (T4), triiodothyronine (T3), and thyroid-stimulating hormone (TSH).

For the single-dose trial, hormone levels were analyzed over an eight-hour period after participants took a single dose of an NSAID. For the one-week trial, doses were taken daily and hormone levels were analyzed daily as well.

In the end, researchers found that ibuprofen, naproxen, and indomethacin (either as a single dose or a one-week course) did not affect any thyroid hormone levels. However, single and weekly doses of aspirin and salsalate decreased various T4 levels, while single doses of meclofenamate increased levels.

These effects were short-lived, and even when thyroid hormone levels were affected, levels stayed within the normal range for the majority of participants.

Despite the findings, the JCEM study is limited in several key ways. Only a small group of people were included, none of whom had thyroid disease or any other chronic illness. The study didn't examine the long-term effects that NSAIDs may have on thyroid function, either.

Since these two studies took place, no new studies have been done to examine the effect that NSAIDs have on the thyroid. Before any clear conclusions can be made, more research will need to be done.

Implications for Your Care

Perhaps these results suggest it's best to choose ibuprofen or Aleve over aspirin for your run-of-the-mill muscle or joint pain, especially if you are concerned about your thyroid hormone levels.

Even so, the JCEM study is really too small to draw any definite conclusions. Until the study is expanded to include more participants with a range of health conditions, you shouldn't concern yourself too much with the findings.

Summary

When taken orally, NSAIDs affect functions and systems all throughout the body. Researchers have done small studies to uncover whether or not NSAIDs affect thyroid function, but they haven't found much to be concerned about.

Taking an NSAID when you need it shouldn't affect your thyroid, even if you have thyroid disease. But if ever you feel unsure, or if you wonder which NSAID you should take, talk to your healthcare provider.

A Word From Verywell

NSAIDs are popular and highly effective medications. The downside is that, because they work throughout the body, they may target various tissues, causing undesirable side effects. This is why it's important to only take an NSAID under the care of your healthcare provider and to take the lowest dose for the shortest period of time as needed.