Should You Take Your Thyroid Medication Sublingually?

Are Thyroid Drugs Effective When Taken Under the Tongue?

thyroid medication, sublingual thyroid medication, natural desiccated thyroid, NDT
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Thyroid patients regularly write in to ask: "I've been told by other patients that I should I take my thyroid medication sublingually because it works better. Is that true?"

Let's take a look at some of the issues behind the question.

First, sublingual refers to taking your thyroid pill and either crushing it and placing it under your tongue or allowing it to dissolve under your tongue.

Second, the question about sublingual use of thyroid medications is always related to natural desiccated thyroid (NDT) drugs like Armour Thyroid or Nature-throid. That is because these drugs include the thyroid hormone triiodothyronine (T3), which is faster-acting and has a far shorter half-life than the synthetic T4 found in levothyroxine drugs like Synthroid and Levoxyl. Some people feel the effects of T3 very quickly, even within an hour or two, but a levothyroxine drug typically takes days to be converted into the T3 that is ultimately usable by your body.

Third, the argument that is made for taking thyroid medication sublingually is that by doing so, the thyroid medication is absorbed through the mucous membranes in your mouth, and goes straight to the bloodstream. This supposedly prevents the absorption of your thyroid medication from being affected by things like calcium supplements, iron supplements, food, coffee, or fiber, all of which are known to block thyroid medication absorption.

Doctors and Drug Companies Share Their Thoughts on Taking Natural Thyroid Sublingually

To explore the issue further, a survey was conducted among a number of doctors, drug companies, and other experts.

The consensus? The active ingredients in thyroid medication have molecules that are so large that it is difficult for them to pass through your mucous membranes. Most of the dissolved/crushed medication still ends up being swallowed and moves through your digestive system in the usual way. Other factors also affect sublingual absorption, including oral pH and salivary enzymes.

Thyroid expert Kent Holtorf, MD, founder of the National Academy of Hypothyroidism, and the Holtorf Medical Group network of clinics, has found that thyroid medication was not designed for sublingual use. He believes that the size of the thyroid hormone molecule means that sublingual use of thyroid medication may not be optimal for some patients as far as absorption, and is not likely to prevent interactions that can reduce absorption.

Several natural thyroid drug manufacturers were also contacted, and while they refused to go on the record publically, they concurred that sublingual administration of natural desiccated thyroid does not prevent other substances such as iron, calcium, fiber, and coffee from impairing absorption.

Some Patients Claim to Feel Better Taking Natural Thyroid Sublingually

Still, some thyroid patients report anecdotally that they:

  1. feel better when taking NDT sublingually
  2. are able to take their thyroid medications sublingually, along with coffee, breakfast, or supplements with iron and calcium, and still maintain good thyroid function
  3. feel better and have improved TSH, Free T4, and Free T3 levels when taking their thyroid medication sublingually 

What could be going on?

Since there have not been any studies to evaluate the effectiveness of the sublingual route for natural thyroid, one can speculate that perhaps these patients may have some sort of digestive malfunction, i.e. rapid digestion, which means that the pill may not even be fully dissolved before it leaves the stomach and goes into the intestines. They also may have insufficient enzymes to dissolve and digest the pill. By crushing/dissolving the pill in the mouth, the pill may be able to break down sufficiently for digestion. 

It would be interesting to see a research study done to compare the two methods of taking natural desiccated thyroid, sublingually versus swallowed, to evaluate the effectiveness of each method as far as TSH, Free T4, Free T3 levels, quality of life and symptoms. An ideal study would also look at subgroups of patients swallowing their medication orally vs. sublingually who drink coffee at the time of their medication, take iron supplements at the time they take their medication, take calcium supplements at the same time, and eat at the same time as their medication.

A Word from Verywell

Keep in mind that if you do decide to take your NDT sublingually you should:

  1. Discuss this with your physician first, before making any changes
  2. Keep track of your symptoms carefully
  3. Have your thyroid levels carefully evaluated 6 to 8 weeks later, including TSH, free T4, and free T3, to ensure that you are not over- or undermedicated.
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