Did you know that the fact that you’re not absorbing your medication properly, could be a hint to the root cause of your thyroid condition?
As a pharmacist trained in conventional, integrative, functional, and natural medicine, I have a deep respect for various healing modalities… including medications. However, my years of experience as a clinical consultant pharmacist have also taught me that medications are often used inappropriately.
I certainly see this all of the time with respect to thyroid medications. People with overt thyroid symptoms are denied thyroid medications because their “numbers are normal.” Other times, they’re given the wrong meds, or not enough of the right ones. While I often talk about various healing modalities that we can use to take back our health, for many of us with Hashimoto’s, thyroid hormone medications are also often a critical part of the healing journey.
One area that is often overlooked when dosing thyroid medications is the role that absorption plays in how well a person does on a particular medication, and how the other ingredients present in the thyroid medication affect absorption.
For example, many thyroid medications contain lactose, and we know that dairy intolerance is a common symptom for many people with Hashimoto’s. A recent study found that people with lactose intolerance needed higher doses of thyroid medication to get their thyroid stimulating hormone (TSH levels) within optimal ranges. For others, it could be due to an underlying infection; and yet for others, it could be due to the timing of your medications. If you’ve found that you have to keep increasing your thyroid medication dosage to get your hormones into normal ranges, this might be a clue to your root cause.
Read on to learn more about:
- What factors affect thyroid medication absorption
- Dairy/lactose issues and Hashimoto’s
- Infections contributing to absorption issues
- Drug, food and supplement interactions contributing to absorption issues
- How to optimize your medication for better absorption
How Well Are You Absorbing Your Thyroid Medication?
Thyroid medications have a narrow therapeutic index (they are referred to as “Goldilocks” medications, as they have to be dosed “just right” to be effective and to prevent adverse effects). Therefore, if the absorption is inconsistent, you can sometimes get too much or too little. This can cause fluctuations between hyperthyroidism and hypothyroidism symptoms.
Several studies consisting of patients receiving levothyroxine (T4 medication) therapy, have shown that a large percentage of patients (40-48 percent) are over- or undertreated. One 2014 study found that, even with frequent dose adjustments and monitoring, 37 percent of people taking levothyroxine often still had TSH levels outside of the normal reference range. This is often a result of inconsistent absorption.
While everyone is a bit different, for the most part, many of my clients and readers feel best with a TSH between 0.5 and 2 μIU/mL. (For the purpose of this article, I will be focusing on optimizing TSH. However, please note that there are also the free hormone levels to consider, including free T4 and free T3, thyroid antibodies, as well as other imbalances/root causes that may contribute to symptoms).
I always say that optimizing a person’s thyroid medication is both an art and a science: so many factors can impact your medication’s effectiveness. I recommend finding a trusted functional practitioner who is able to titrate and prescribe the perfect dose and formulation (T4, T3, or a combination of both) for your particular thyroid health status.
Ideally, your practitioner should also be aware that certain factors, such as fillers in your medication, underlying infections, and low stomach acid, in addition to having acid reflux, food sensitivities, or digestive issues, or taking your medications with your morning cup of coffee, can potentially sabotage your medication’s absorption, and thus effectiveness.
Finding Your Optimal Dose
Your practitioner can help you determine your optimal medication dose, but there are some strategies to help you determine if the medication you are taking is being properly utilized. To determine how well you are absorbing your thyroid medications, you first need to find your appropriate control dose, or the dose at which your thyroid hormones fall within optimal ranges.
Researchers have found that the average person with Hashimoto’s requires a median dose of 1.31 mcg/kg/day of levothyroxine, to bring their average TSH levels to right around 1 mU/L (that would be right around 90 mcg of levothyroxine for a 150 pound person).
If you require more than that, this would be a clue that you may not be absorbing the medication properly.
First, you will need to figure out how many micrograms of levothyroxine you are currently taking for each kilogram you currently weigh, or your current “mcg/kg” dose of thyroid medication.
Math refresher: If you are taking levothyroxine, Synthroid, Levoxyl, Tirosint or another version of T4, take your current dosage of levothyroxine in micrograms, then divide it by your weight in kilograms.
For my American and British readers, to figure out your weight in kilograms, take your weight in pounds and divide it by 2.2.
If you are taking Armour, Nature-Throid, NP-Thyroid, compounded T4/T3 or another mix of T4 and T3, here’s a handy conversion chart if you take NDT medications to determine your equivalent levothyroxine dose.
Interpreting Your Results
If your TSH is around 1 mIU/L, and your “mcg/kg” dose is 1.31 mcg/kg or less, this is an indication that you are absorbing your thyroid medications well and your remaining triggers are likely to be outside of your gut.
If your TSH is >1 mlU/L, and your dose is 1.31 mcg or higher, you may have lactose intolerance at the root of your thyroid dose issues. The lactose in your diet (and potentially in the medications) may be an issue for you.
If your dose is 2 mcg/kg or more, consider lactose intolerance plus a gut disorder that could be inhibiting your medication absorption and potentially be the root cause of your condition.
Let’s talk about each of these potential root causes.
Are You Taking Your Thyroid Meds Correctly?
If you find that your medication dose is outside of range of the control dose (or your optimal dose as determined by the formula above), the first question to ask yourself is, are you taking your medication correctly?
Most thyroid medications (with the exception of Tirosint and Tirosint-SOL) should always be taken on an empty stomach, at least 30 minutes before your first meal of the day. (Some people may even need to wait 1-2 hours if they have additional gut issues.)
Medications should be consumed with a full glass of water and spaced out from other medications or supplements, by at least one hour.
Calcium, iron, antacids, and cholesterol-lowering medications have all been shown to interfere with thyroid medication absorption and are often recommended to be taken at least four hours away from thyroid medications.
There are also certain foods to avoid within one hour of taking thyroid medication, including coffee, soy, grapefruit juice, cottonseed meal, walnuts, and dietary fiber.
If you are following these guidelines, are dairy-free and still find yourself having to increase your medication dose, an absorption issue related to a filler in your thyroid medication (such as lactose) might be something to consider.
Thyroid Medication Fillers
The inactive ingredients (fillers) within your given hormone medication need to be considered, as those can sometimes impact how your body will respond to your medication, and many of my clients experience sensitivities to the many fillers found in their T4 and NDT medications. (These have also been shown to affect the absorption rate and effectiveness of the very medication meant to help the thyroid!)
If you were to check the ingredient information listed for most thyroid medications, you’ll find a number of inactive ingredients. These may be used as bulking agents to stabilize the tablets, as preservatives, as coloring agents, or as an aid in manufacturing in some way.
Disintegrants (some examples being starches and cellulose) are added to help promote the breakup of the tablet into smaller pieces when the tablet hits an aqueous environment (such as when you drink water with your meds, or when your meds touch the saliva in your mouth). This promotes a more rapid release of the medication.
Synthroid contains lactose as well as corn starch, confectioners’ sugar, magnesium stearate, talc, povidone, and color additives. As another example, Levoxyl contains five inactive ingredients, including an anti-caking agent, a filler, a rapid disintegrant, an antacid, and a flow agent (along with two dyes made from coal tar).
Here’s a list of some of the most common inactive ingredients that you might find in your thyroid medication. A sensitivity to one or more of the ingredients can potentially interfere with medication absorption.
- Lactose monohydrate
- Modified wheat starch (gluten)
- Confectioners’ sugar (may contain corn starch)
- Corn starch
- Microcrystalline cellulose
- Calcium stearate
- Mineral oil
- Medium chain triglycerides
- Sodium starch glycolate
- Opadry white
- Colloidal silicon dioxide
- Dicalcium phosphate
- Magnesium stearate
- Croscarmellose sodium
- Stearic Acid, Opadry II 85F19316 Clear
- And many more…
While these ingredients are only present in small amounts, any one of these can cause an adverse reaction in a sensitive individual, and some fillers are more reactive than others.
According to the package insert for Unithroid, “Hypersensitivity reactions to inactive ingredients have occurred in patients treated with thyroid hormone products. These include urticaria, pruritus, skin rash, flushing, angioedema, various gastrointestinal symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness and wheezing. Hypersensitivity to levothyroxine itself is not known to occur.”
In addition to hypersensitivity reactions like the ones listed above, studies have found that inactive fillers and formulations can lead to potential issues with the absorption of thyroid medications, lactose being the most well described reactive ingredient in the research.
For some people with lactose intolerance, the amount of lactose in thyroid medications may not be enough to impair absorption (a dairy research article mentions that even a full glass of milk may be tolerated by many people with lactose intolerance). However, for individuals that are more sensitive, even the small amounts of lactose (and potentially other inactive fillers) can be an issue.
As an individual can be reactive to just about anything, I generally believe that the fewer filler ingredients are present in our medications, the less likely we are to react, and the more likely we are to absorb them.
For this article, I’m going to focus on lactose, as this ingredient has the most research behind it in causing medication absorption issues in hypothyroidism. However, please note that any inactive ingredient could be a potential issue.
The Dairy Problem with Hashimoto’s
Dairy is a common food sensitivity for those with Hashimoto’s. Cow’s milk contains a mix of sugar (lactose), protein (whey and casein), and fat (ghee). People can be sensitive to any of the three components of dairy. However, reactions to lactose and the dairy protein casein are the most common.
Some people with Hashimoto’s may be able to tolerate butter and clarified butter (known as ghee) because they contain very small amounts of dairy proteins, but even tiny amounts of butter caused me to have a reaction at the start of my Hashimoto’s journey.
Like many people with Hashimoto’s, I became sensitive to casein and whey, and going dairy free resolved three years of acid reflux in just three days. (Read more about my dairy sensitivity here. These days I am no longer dairy sensitive, and will share my protocols for reversing this in future newsletters).
That said, the dairy sugar lactose is a common intolerance in Hashimoto’s as well, and during pharmacy school, I learned that even tiny amounts of it in our medications, can have a profound impact on our ability to absorb them if we happen to have a high degree of lactose intolerance. One important service provided by compounding pharmacists is recreating hypoallergenic versions of commercially available medications and making them free of reactive fillers, for sensitive patients.
An August 2014 study published in the Journal of Clinical Endocrinology and Metabolism by Cellini and colleagues, found that lactose intolerance increased the requirement for thyroid medications.
Remember that I had you calculate your mcg/kg dose of levothyroxine at the beginning of this article? This number can help you determine if you are absorbing your medications correctly.
A person with Hashimoto’s and lactose intolerance who continued to consume lactose, needed a dose of 1.72 mcg/kg/day to reach the same goal (that would be like 116 mcg of levothyroxine for the same 150 pound person — a big difference).
Furthermore, patients who had another gut disorder in addition to lactose intolerance, required an even higher dose to get to their goal TSH level of 2.04 mcg/kg/day, or around 140 mcg for a 150 pound person (1.5 times the average dose).
Whenever I see people whose TSH levels fluctuate and who have a hard time adjusting their medication up and down, who are still eating dairy, I always recommend the dairy-free diet as a first step. I imagine the changes in TSH occur as a result of varying amounts of lactose a person may have on various days.
How Common Is Lactose Intolerance in Hashimoto’s?
Lactose intolerance rates in Caucasians have been reported to be between 7 percent and 20 percent, and much higher in people of Asian, African, Arab, Jewish, Greek, and Italian descent. (It is estimated that over 65 percent of the world has some degree of lactose intolerance.) I believe that various health conditions can also contribute to lactose intolerance.
Lactose intolerance can be genetic and permanent, or secondary to another condition, and reversible. People with SIBO and celiac disease are often lactose intolerant when first diagnosed, but once they address SIBO and celiac disease, many times they find that their ability to tolerate lactose returns after three to six months. (We’ll discuss testing for lactose intolerance further on in this article.)
A 2006 paper in the journal Thyroid described one woman with lactose intolerance and Hashimoto’s, and determined that lactose intolerance was a rare occurrence in causing malabsorption of thyroid medications. However, a more recent study in 2014 by Asik and colleagues tested 83 Hashimoto’s patients for lactose intolerance and found lactose intolerance in 75.9 percent of the patients!
Of those patients, 38 were instructed to start a lactose-free diet for eight weeks, and the researchers found that over this time, the patients’ TSH dropped, meaning, they were absorbing their thyroid medications better.
So, if you are someone that can’t get your TSH into your sweet spot (TSH should be between 0.5-2 μIU/mL for most people to feel their best) despite taking escalating doses of thyroid medications, consider lactose intolerance and the possibility that the lactose in your diet or even in your thyroid medication (for those particularly sensitive) may be inhibiting its absorption.
I suggest checking your thyroid medication for lactose as an added ingredient and talking with your practitioner about switching to a lactose-free option.
Lactose-Containing Thyroid Medications
- Armour Thyroid*
- WP Thyroid*
- NP Thyroid*
- Most generic brands of levothyroxine – check with your pharmacist
- Most compounded medications – check with your pharmacist
*Most NDT medications don’t add lactose as a filler. However, they do use lactose in the manufacturing process, so there may be very small amounts of lactose in the tablet. Also please note, at the time of writing this article, NP Thyroid, Nature-Throid & WP-Thyroid were recalling certain lots of medication due to potency issues.
I generally update the articles on this website every 1-2 years, and as the formulations and availability of various generic levothyroxine brands can change often, please consult with your pharmacist to ensure that you have the most up-to date and correct information.
Lactose-Free Thyroid Medications
- Tirosint SOL
- Some compounded medications, check with your pharmacist
- Some generic brands of levothyroxine, check with your pharmacist
I generally update the articles on this website every 1-2 years, and as the formulations and availability of various generic levothyroxine brands can change often, please consult with your pharmacist to ensure that you have the most up-to date and correct information.
Of all of the T4-containing medications, Tirosint and Tirosint SOL have the fewest fillers that may impair absorption, and these two medications were specifically designed for this purpose. I’ve had many clients, readers and people on my Facebook page comment on how they felt much better on Tirosint as compared to other levothyroxine medications.
Tirosint contains levothyroxine sodium dissolved in gelatin, glycerin and water. It came to the United States in 2017. The gel caps are free of inactive filler ingredients such as gluten, lactose, dyes, and preservatives that might cause tolerability or absorption issues.
Tirosint-SOL is available in liquid single-dose ampules and only contains two inactive ingredients (glycerol and water).
Of course, many people do not feel good on T4-only medication and that is beyond the scope of this post, but you can read more about that in my article Which Thyroid Medication is Best.
Of all of the T4/T3 combination medications, WP Thyroid contains the fewest fillers that can impair absorption. The inactive ingredients are inulin derived from chicory root and medium chain triglycerides derived from coconut.
Can Taking a Lactase Supplement Help?
As my community is full of extremely smart and motivated people interested in finding solutions, someone is sure to ask… “What about taking Lactaid (a supplement that contains lactase, an enzyme that breaks down lactose) with your thyroid medications? Will that help with the absorption of the medication?”
This is a really interesting question… In theory, it should work, but I have not tested that theory yet. If any of you have had experience with taking Lactaid in conjunction with your lactose containing thyroid medications, I’d love for you to share your experience — did it help you feel better? Did it help normalize your TSH?
In recent years, I’ve been super excited to hear from researchers who want to collaborate on studies with me, and while I can’t say yes to every opportunity, this would also be a great research study for any of the researchers following my work. 😉 (Please reach out to my team at email@example.com to make it happen!)
As far as diet, I have personally seen tremendous improvements in my health and the health of clients and readers, on a dairy-free diet, so this is something that I wholeheartedly recommend across the board for people with Hashimoto’s.
Other Factors Contributing to Medication Absorption Issues
If lactose intolerance doesn’t seem to be an issue for you, or if you are taking the lactose intolerance dosage and still not absorbing your medications well, this would indicate that something else is going on…
Again, are you taking your medication correctly, away from food, coffee, and other supplements or medications?
Are your medications free of dairy, gluten or other fillers that are problematic for you and may be preventing proper absorption?
If you answered yes… it might be time to dig deeper to look for an infection that could be inhibiting proper medication absorption in your gut.
As I mentioned earlier, if your dose is 2 mcg/kg or more, consider lactose intolerance along with another gut disorder that could be inhibiting your medication absorption and potentially be the root cause of your condition.
Other factors besides lactose intolerance that can affect absorption include celiac disease, atrophic gastritis, H. pylori infections, Blasto, Giardia, inflammatory bowel disease, and various parasitic infections. When we have gut bugs, they can make us super sensitive to EVERYTHING (even “healthy” things that are good for us).
You may want to consider having functional medicine tests for the following root causes: SIBO (Small Intestinal Bacterial Overgrowth 2-Hr Lactulose-Genova); parasites and other gut infections (GI-MAP, GI Effects Comprehensive Stool Analysis). You can order these tests through your doctor or through the links provided.
Interestingly, in my experience, many of these are also potential root causes of autoimmune thyroid disease, and addressing some of these has helped people get into remission. (Read more in my article 6 Hashimoto’s Root Causes.)
Testing is available through most conventional doctors for celiac disease, atrophic gastritis (often caused by H. pylori), or inflammatory bowel disease. (I hope to share an IBD protocol I used with a family member to reverse ulcerative colitis soon.)
For H. pylori, Giardia, and other parasitic infections, a functional medicine doctor can order tests for you, or you can self-order them through the links provided further on in this article.
Please note, another study found that 54 percent of people with hypothyroidism had SIBO, and one of the symptoms of SIBO is lactose intolerance. While this study found that treating SIBO helped the many digestive symptoms experienced by the patients, treatment of SIBO didn’t increase the absorption of thyroid medications.
I wonder if this is because the lactase enzymes do take a few months to regenerate if they do come back at all after treating SIBO, and the participants in the study were not placed on a lactose-restricted diet.
Regardless, it’s important to find out if you have SIBO because this can be an underlying root cause of Hashimoto’s, and treating the SIBO can not only help your sugar digestive enzymes to regenerate, but can also result in remission from Hashimoto’s, in some cases. SIBO has become a hot topic in the gut world, so some more progressive doctors may be willing to test you for it. Otherwise, you can self-order a 2-hour Small Intestinal Bacterial Overgrowth lactulose breath test.
Low stomach acid (which is very common in Hashimoto’s) can contribute to poor absorption of many things, including thyroid medications. Some patients take their thyroid medications with a glass of water that includes squeezed lemon juice or a teaspoon of apple cider vinegar. I have personally had excellent results with using Betaine with Pepsin to support stomach acid.
Finding the right thyroid medication and the right dosage, are crucial parts of getting your thyroid numbers within optimal ranges and feeling better with Hashimoto’s. This may require some level of experimentation, and being your own Root Cause detective to determine if there are any factors that are prohibiting you from absorbing your thyroid medications properly — such as added ingredients, underlying infections, or gut issues.
Because such a large group of people with Hashimoto’s have a sensitivity to dairy, I always recommend looking at lactose intolerance as a possible culprit when medications aren’t being properly absorbed. Many times, removing dairy from both diet and medication can result in more stable thyroid hormones and a relief from many symptoms of Hashimoto’s, including acid reflux, fatigue, joint pain, and skin issues (among others!).
I highly recommend finding a like-minded physician who can help you determine the right medication and dosage for you.
If you would like more guidance on uncovering your own root cause(s) and triggers, please read my books Hashimoto’s: The Root Cause, and Hashimoto’s Protocol. In them, you’ll find a step-by-step guide to getting yourself into remission and taking your life back.
I hope this information helps you on your journey to feeling your best!
P.S. To help you on your journey, you can download a free Thyroid Diet Guide, 10 thyroid friendly recipes, and the Nutrient Depletions and Digestion chapter of my Hashimoto’s: The Root Cause book for free by signing up for my weekly newsletter. You will also receive occasional updates about new research, resources, giveaways, and helpful information.
- Lauritano, AC, et al. Association between hypothyroidism and small intestinal bacterial overgrowth. J Clin Endocrinol Metab. 2007 Nov;92(11):4180-4. Epub 2007 Aug 14.
- Ruchala M, et al. The influence of lactose intolerance and other gastro-intestinal tract disorders on L-thyroxine absorption. Endokrynol Pol. 2012;63(4):318-23.
- Asik M, Gunes F, Binnetoglu E, Eroglu M, Bozkurt N, Sen H, et al. Decrease in TSH levels after lactose restriction in Hashimoto’s thyroiditis patients with lactose intolerance. Endocrine. 2014 Jun;46(2):279-84.
- Cellini M, Santaguida MG, Gatto I, Virili C, Del Duca SC, Brusca N, et al. Systematic appraisal of lactose intolerance as cause of increased need for oral thyroxine. J Clin Endocrinol Metab. 2014 Aug;99(8): E1454-8. doi: 10.1210/jc.2014-1217. Epub 2014 May 5. PMID: 24796930
- Muñoz-Torres M, Varsavsky M, Alonso G. Lactose intolerance revealed by severe resistance to treatment with levothyroxine. Thyroid. 2006 Nov;16(11):1171-3.
- Lactose Intolerance. U.S. National Library of Medicine website. https://ghr.nlm.nih.gov/condition/lactose-intolerance#statistics Accessed August 25, 2020.
- Armour Thyroid Product Prescribing Information. https://media.allergan.com/actavis/actavis/media/allergan-pdf-documents/product-prescribing/06-2018-Armour-Thyroid-PI-final.pdf. Published February 2020. Accessed September 2020.
- NP-Thyroid Prescribing Information. https://npthyroid.com/wp-content/uploads/2020/02/NP-Thyroid-flat-PI-10-15-19A-FPO.pdf. Published June 2018. Accessed September 2020.
- Tirosint Prescribing Information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/021924s013lbl.pdf. Published December 2017. Accessed September 2020.
- Tirosint SOL Prescribing Information. Accessed September 2020. https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/206977s000lbl.pdf
- Cytomel Prescribing Information. http://labeling.pfizer.com/showlabeling.aspx?id=703. Published July 2019. Accessed September 2020.
- Levoxyl Prescribing Information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/021301s026lbl.pdf. Published October 2007. Accessed September 2020.
- Unithroid Prescribing Information. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=07562e72-7eaa-4ce6-94f0-e08814787e50&type=display#section-13. Revised June 2019. Accessed September 2020.
- RLC Labs, Inc., Issues Voluntary Nationwide Recall of All Lots of Nature-Throid® and WP Thyroid® with Current Expiry Due to Sub Potency. US Food and Drug Administration website. https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts/rlc-labs-inc-issues-voluntary-nationwide-recall-all-lots-nature-throidr-and-wp-thyroidr-current. Published September 3, 2020. Accessed September 21, 2020.
- Acella Pharmaceuticals, LLC Issues Voluntary Nationwide Recall of Certain Lots of NP Thyroid® (Thyroid Tablets, USP) Due to Super Potency. US Food and Drug Administration website. https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts/acella-pharmaceuticals-llc-issues-voluntary-nationwide-recall-certain-lots-np-thyroidr-thyroid. Published May 22, 2020. Accessed September 21, 2020.
- Lactose Intolerance: Health Authorities’ Recommendations. Dairy Nutrition website. https://www.dairynutrition.ca/scientific-evidence/lactose-intolerance-and-milk-allergy/lactose-intolerance-health-authorities-recommendations. Accessed September 21, 2020.