When T3 Doesn’t Work — Why Thyroid Medication Can Make You Feel Worse (Part 1)

Beyond the Thyroid – Episode 45: When T3 Doesn’t Work — Why Thyroid Medication Can Make You Feel Worse (Part 1)

In this episode of Beyond the Thyroid, Dr. Dana Gibbs tackles a frustrating and surprisingly common problem: why T3-containing thyroid medications don’t always help—and can sometimes make patients feel worse.

Drawing from years of clinical experience and personal insight, Dr. Gibbs explains that when T3 “fails,” the problem is often not the medication itself, but the physiology surrounding it. She walks through the most common reasons T3 is poorly tolerated, including stimulant sensitivity, blood sugar instability, cortisol dysregulation, circadian rhythm disruption, and nutrient deficiencies.

Dr. Gibbs shares the real-life case of a patient named Barbara, illustrating how strategic changes to medication timing, lifestyle factors, and metabolic support led to dramatic improvement after years of struggle. She also provides practical guidance for patients and clinicians on how to safely optimize T3 therapy.

This is Part 1 of a deeper series on T3 therapy and thyroid optimization.

Tune in to understand why T3 doesn’t always work—and what to fix before giving up on it.

📑 Join the The Thyroid Clarity Checkup Priority List! 

📁 Get My Free Lab Ordering Guide for Thyroid Health

📲 Follow Dr. Dana Gibbs on the Goodself App!

🩺 Interested in a Discovery Call with Dr. Dana? Click here!

📺 Watch on YouTube

Episode Highlights
00:34 – Why T3 Medications Often Fail
01:04 – Dr. Gibbs’ Personal Journey
02:27 – Common Problems with T3 Therapy
04:30 – Case Study: Barbara’s Experience
08:12 – Factors That Affect T3 Tolerance
08:45 – Stimulants and T3 Sensitivity
10:56 – Blood Sugar and Thyroid Hormones
12:20 – Circadian Rhythm & Sleep Issues
14:23 – Cortisol and Stress Effects
16:09 – Nutrient Deficiencies That Block Progress
19:34 – Key Takeaways and Next Steps

Understanding T3 is about timing, metabolism, and context—not just dosage.

Let's connect! 🔔
Facebook - Consultants In Metabolism
Instagram - @danagibbsms
LinkedIn - Dana Gibbs MD
Tiktok - @dana.gibbs.md

✉️ Email Dr. Gibbs at drgibbs@DanaGibbsMD.com or visit https://www.danagibbsmd.com/ for more information.


Thank you so much for listening! Tune in on the next episode.


The medical information provided in this episode is intended for informational purposes only and should not be construed as medical advice. Always consult a qualified healthcare provider regarding any medical questions or concerns.

Transcript

dana-gibbs-md--she-_2_12-21-2025_161910 0:00

You're listening to the Beyond the Thyroid Podcast. Today we are discussing one of the most frustrating experiences I hear about from patients. You finally found a doctor to believe you about your hypothyroid symptoms and prescribe a T3 containing medication. Maybe it was Armour or NP thyroid. Maybe it was generic T3, but when you tried it, you felt worse. Maybe wilting with a fatigue, maybe faint, shaky, anxious, irritable, palpitations, maybe all of that. So you think, oh my goodness, I tried T3. It didn't work. Now I'm screwed. Nothing is gonna help me. Spoiler alert, it's not usually about the medicine itself. So on today's episode, we're gonna unpack what probably went wrong. But first, if this sounds like you and you're looking for one-on-one help with your thyroid. Book a free introductory call today at danagibbsmd.com/call. I have licenses now in three new states and are adding more for 2026.

1:01

You're listening to the Beyond the Thyroid podcast. I'm your host, Dr. Dana Gibbs. I'm an ENT surgeon and hormone specialist. For years, I struggled with my own unrecognized thyroid problems before and even after I was regularly performing thyroid surgeries. Then, one day, I learned something that turned my health around and opened my eyes to the limits of mainstream medicine in treating more subtle thyroid abnormalities. I spent the next 20 years fine tuning my hormone expertise in disorders like Hashimoto's disease, perimenopause, and stress related illness. Come join me as I share this new approach to hormones that empowers you to take control of your own thyroid and hormone imbalances. Let's dive in.

dana-gibbs-md--she-_5_12-21-2025_162258 1:54

Hello, and welcome back to the Thyroid, my friends. If you're new here, welcome. I am Dr. Dana Gibbs and I help people with Hashimoto's symptoms and normal TSH get their energy back. So if you've been enjoying the episodes, please take one minute to review the podcast. It is so simple and it'll help more people like you find this vital information source. So how you do it? Go to the episode thumbnail, tap the three dots in the bottom right corner. Then scroll to go to show, then scroll all the way down to write a review. I read and appreciate every one of these, and I would love to hear from you. Today we're going deep on a problem that comes up very frequently in my clinic. Many patients finally discover T3 containing medications after years of being told their labs are normal, or after T4 only meds like levothyroxine really fail to improve their symptoms. Online groups are full of people who are all about the desiccated thyroid products or ine synthetic T3, but every week, there is a new patient coming into my office saying,"Hey, my doctor put me on T3 and it made everything even worse. Can you help me?" And they thought this new medication was gonna be a miracle, and instead it can feel like a nightmare. So, which is it? In my experience, it's usually not the fault of the medicine. It's because other factors around the prescription were not optimized either before starting or as the dosing was ramped up. So today I'm gonna show you why that happens and some pointers to help fix it using a framework that has been refined over 35 years of clinical practice, both mine and my mentors. So within this system, T3, as indicated by the lab set that I consistently use really helps patients feel dramatically better on T3 with minimal side effects and without the long-term risk that many doctors worry about with T3. And if you're a clinician that's listening to this, I really wanna say clearly this episode is not about blaming doctors. The American Thyroid Association guidelines actually acknowledge that T3 may be useful in certain situations, and the medical literature now says about 20% plus or minus of patients who don't resolve their symptoms on T4 do better with a T3 containing medication. But the guidelines don't give us any guidelines on how to do that safely. So doctors in general are not taught how to do this. They're following the rules. The rules are incomplete. The patients are trying to advocate for themselves, but they also have no roadmap. My goal in this, and I think I'm gonna make it into a two-part series because there's just a lot of information here I wanna share with both patients and clinicians what's working for my patients. And I wanna start with another story. Today I wanna talk about Barbara. She came to me last year, absolutely exhausted. She was overwhelmed, discouraged, worried that she was slipping into dementia. That's how bad her brain fog had become, and she'd been prescribed what looked like an appropriate amount of T3, but the catch, she was also taking levothyroxine and it turned out that it was a lot more than her body could tolerate once we added that T3 in. So she was told to take it in the standard way and get her labs first thing in the morning, and that's the way things had been done for years since Synthroid became the hot new thing on the market back in the 1970s. It's very standard, but it's really not based on the ideal thyroid physiology. So for Barbara, within a few weeks of starting that regimen, she began feeling worse than ever, severe diarrhea, interrupted sleep, escalating anxiety, racing, heart, sugar cravings, and cognitive fog that was so intense that it was frightening to her. Her family genuinely wondered whether she was developing dementia, and after the first couple of interactions, I actually was worried about that too. But the very first thing we did with her was change her timing. I split her T4 dose up as my standard. I re-timed her T3 to take that also twice a day. And I ran the labs at a more ideal time, and the truth appeared immediately once I had those labs back. That her T3 dose was about right, but her body just wasn't ready for it because her dose of levothyroxine was way too high. Her reverse T3 was telling us that her body was desperately trying to inactivate thyroid hormone, and we were forcing that into activation, which was not helpful for her at first. So I slowly reduced her T4. I temporarily backed the T3 down a bit, and over time the diarrhea and the anxiety slowly resolved, and once we got her stabilized and put back the T3, it turned out that she was actually on the right dose overall. She needed a more physiologic rhythm and more stability around that with other things that were going on in her body. And when we got that there, her stomach problems cleared up, her sleep normalized, her energy returned. She found she was able to exercise for the first time in years, and that brain fog that had terrified her was finally gone. First time in a really long time. So her family went from suspecting dementia to getting their mother back, and it was, it was very interestingly, like a switch. It's like I got on the call with her and immediately I could tell that she was sharp, sharp, sharp. Anyway, when she first arrived in my office. The problem was not that the T3 had failed, it was that her body was being asked to increase metabolic output in an environment that was not supportive. So you have to adjust the context, not just the medication. And when we did that, it got better for her. And this is true in general, when T3 feels overstimulating or intolerable or unpredictable in its results. The first thing I evaluate is not the dose of T3, it's the physiologic environment and the whole patient. So T3 is powerful. It's the active thyroid hormone. It increases metabolic demand on the system, on the body. And if the system that support energy regulation aren't prepared, people will feel that immediately and not in a good way because T3 can bypass the checks and balances our bodies have around getting overstimulated, and that's one of the reasons T3 has a bad rep in the endocrinology community as a whole is because it really can, it can bypass the checks and balances we have on hyperthyroidism, which is potentially deadly if you get too much. Anyway for Barbara, as for so many others, the problem was not the T3, it was everything else around it. So I'm gonna share with you five systemic categories that can make it look like T3 doesn't work. These situations are the ones I want every clinician and every patient to be aware of, because once you recognize them, you will understand why the T3 failed and you'll understand where to look to fix these systemic problems. So first one is stimulants, the next one, blood sugar. Next one, cortisol, then sleep, and then nutrition. And if these pieces are not optimized, you are gonna feel your T3 in the wrong ways. So let's look deeper into what I'm talking about here. First thing I wanna talk about is stimulants. One of the most common issues I see is the emergence or reemergence, I guess, of stimulant sensitivity. So people will suddenly feel jittery, anxious, or wired, and they'll blame the T3. In reality, their body is finally responding normally to the giant amount of caffeine that they take for the first time in years. So they tell me"hey, I've been drinking a pot of coffee every day for years, and it's never kept me awake at night or phased me in any way." Well, when you start T3 and it wakes your metabolism up, your caffeine suddenly hits much harder. As a matter of fact, it does what it does in normal people really, but people don't associate that sudden, shaky, jittery, trouble falling asleep with the caffeine. They immediately blame the T3. People may also find that they're now waking up in the middle of the night if they weren't already having that problem before. When you start T3, your metabolic activity in your system starts waking up. So now your body is responding basically in the normal way to the load of stimulant that you're consuming. And part of this has to do with the way that caffeine disrupts sleep. So the chemical that builds up in your brain that tells you that you're sleepy is called adenosine. And adenosine is blocked by caffeine. Adenosine wears off as you sleep, and it wears off much faster than caffeine. So the caffeine can block the adenosine, but only to a point. At which time you're like, okay, now I'm so sleepy, I have to go to sleep. So you may fall asleep just fine, but then wake up at 1:00 or 2:00 AM wide awake and wired and tired because the caffeine is still there and still active, even though the adenosine clears out in that first three to four hours of sleep. So, the patient will think the T3 is the problem, but I always look at stimulants first. They may need to completely get off caffeine for a while as they're getting started taking T3. And then when they get their T3 properly dosed, they may not need the stimulants anymore, which is great. I've even found that some people can come off their ADHD medication, not without your doctor's help, of course, but because their lack of ability to focus didn't mean they had ADHD, it was actually related to the thyroid brain fog that they had. All right. Our next issue is blood sugar. And here's a fact that I actually didn't know until I looked it up, and that's that insulin resistance is twice as common in people with Hashimoto's antibodies than it is in the general population, and it's already pretty high. So in Hashimoto's patients, it's 68% of them have insulin resistance, and this can be a huge factor in apparent T3 intolerance for a particular reason. So T3 helps your cells burn glucose faster, which is exactly what we want. So it also increases the demand for insulin. But if you're eating a lot of refined carbohydrates and sugary snacks, the insulin levels can lag and then overshoot. And when that happens, your blood sugar will shoot very high, and then your insulin levels will overshoot, and then the sugar wears off, your blood sugar drops, and then you get that adrenaline surge, which then causes glucagon to come and bring your sugar back. But the adrenaline surge causes you to feel hot, flushed, shaky, hangry, irritable, lightheaded, racing heart, and people think this is a reaction to the T3. It's not, it's the adrenaline and it can happen with any meal, but particularly the carbs that you eat at bedtime, cause a blood sugar crash between midnight and 3:00 AM which leaves you waking up, sweating, craving all the rest. And again, T3 gets blamed even though the real culprit is the glucose curve. All right, so we already talked a little bit about sleep, but here's the next one, which is circadian mismatch problems and sleep. And I also hear this an awful lot, and that's,"I can't wake up in the morning, but then I get a second wind in the evening and I can't fall asleep." And interestingly, this is a problem, particularly for Hashimoto's patients, but it's, it seems like it's across the board common everywhere. We already touched on how stimulants and blood sugar can cause sleep problems, and this one is a little bit more complex. Sleep is complicated because sleepiness being controlled by an adenosine building up in your brain is one thing. But wakefulness is controlled by your circadian rhythm, which drives cortisol production. And these two systems do not have to completely over overlap. I mean, when they're in an ideal situation, they overlap and they compliment each other, but they can get really off when you have persistent stress. And Hashimoto's disease is a persistent stress on your system. So cortisol, which is produced in your circadian rhythm. Cortisol is the stress hormone. It is controlled by and closely related to the same parts of the brain and pituitary gland that regulate the thyroid. So together, T3 and cortisol normally support your healthy circadian rhythm. Cortisol rises in the early morning. T3 also rises in the early morning to help you wake up when it's time to wake up when the sun comes up, but then it drops later in the day and gets to its lowest point about dusk, about 9:00 PM, when it's time to go to bed, right? But the circadian cortisol curve is very fragile and it can get messed up like by taking T3 at the wrong time of day, and that will make it a lot worse. So a lack of T3 when it's time to make cortisol in the super early morning, and then too much T3 in the late afternoon evening when it's time to wind down for bed, will make it harder to correct this. But the good news is that you can vary the dose of T3 when you take it at the right times, and it'll help with changing that habit of waking up when it's time to wake up and sleeping when it's time to sleep. Alright, so stress is another factor that really seems to be present in most of my Hashimoto's in particular patients, but even in people who don't carry a formal diagnosis of Hashimoto's. Because T3 stimulates your metabolism, it also increases your sensitivity to fluctuations in cortisol and to adrenaline at any time of day. So when you ask your body for more energy output by giving it T3 and the metabolic rate is increasing, sometimes cortisol production can't keep up with the demand and cortisol stimulates glucose in your blood, right? When your metabolic rate accelerates, it's using the glucose up too fast. So if you have low cortisol and an accelerated metabolic rate, you feel weak, faint, dizzy, sometimes you pass out, and that low cortisol and the low blood sugar is then followed by the adrenaline surge. So your body has to do something to get your blood sugar to rise. So if it doesn't have enough cortisol, it uses adrenaline and once again, you get hot, sweaty, shaky, hungry, irritable, lightheaded, racing heart. Persistent high cortisol can result in almost the same issue because when cortisol stays high, the sympathetic nervous system stays activated and sympathetic nervous system is the one that secretes adrenaline. It's also activated more all the time when you have persistent high cortisol. And so then the things that wouldn't bother most people,"oh, my son forgot his lunch, you know, on the table when he was off to school or something like that." Things that wouldn't bother. Most people can send you into a real tailspin and T3 will accentuate that. There are many resources for people who are wanting to lower stress and optimize their cortisol levels. It needs to be a balance, not too much, not too little, especially when you're using T3. And lastly, thing 5 that we're gonna talk about today is nutrient deficiencies. So there are key nutrients that affect your ability to benefit from the metabolic boost of T3. Now, protein is the most obvious one because if you plan to build new muscle tissue from protein, you need more raw materials. Of course, it's not just muscle, it's every tissue in your body that needs to be replenished is stimulated by T3. Your body also cannot use thyroid hormone, especially T3 without certain minerals and B vitamins. So iron is the big one, especially the level of ferritin in your system. That's your stored iron. I have seen in my patients some shockingly low ferritin numbers in people with this exact symptom pattern and with the very low T3, high reverse T3. Mostly that's in menstruating women, but there are other reasons to have very low iron stores. You can have a perfectly normal hemoglobin, and still, if you're not checking ferritin, you're not gonna find out that it's low and you can have a ferritin so low that your cells can't produce or convert T3 very well at all. But even more important than that, low iron causes a similar symptom pattern that looks a lot like hypothyroidism. Extreme fatigue, weakness, pale skin, cold hands and feet, brittle nail hair loss. Sound familiar? There are others too, and I have seen this be so severe that I've recommended my patients actually go get an iron infusion a few times. The American Academy of Family Physicians recently raised their definition for the minimum of a healthy ferritin level and level, so this is something that you should probably get checked with your doctor even if you don't have thyroid problems and if fixing this resolves your symptoms, your body is frequently starting to make and convert T3 on its own again. So it's possible you don't even need to add T3. So if you think you might have low ferritin though, it's really important to get the blood test and talk to your doctor before you just blanket go and supplement iron because high iron levels are toxic and that's something you really should have some coordination with someone who knows what they're doing. Anyway, there's some other minerals I'm just gonna quickly mention. So Selenium, the proper dietary level selenium is required for use of the deiodinase enzymes. Those are the ones that activate T4 to T3 in your body. So particularly the deiodinase 2 is especially dependent on having enough selenium. Magnesium is also essential for T4 to T3 conversion. It also helps with your mood. It helps with circadian rhythm regulation, among other things. And half of us adults failed to achieve even the minimum USRDA of magnesium and their diets. And so a lot of times I'll just send people to the stores like, go get magnesium, start taking magnesium, you know, particularly if you are not terribly inclined to have an ideal diet, and I know if you have no energy, it's very, very tough to get up and cook fresh vegetables and sufficient healthy meals Anyway, zinc helps thyroid receptors respond properly and the B vitamins, B12 folate, B6 riboflavin, thiamin are essential for methylation and mitochondrial energy production. So without being able to produce energy, the T3 stimulation is not gonna work and it's gonna feel like too much, even when the labs say it's fine. And again, patients may blame not tolerating the T3 when in truth their body just simply wasn't capable of supporting that increased metabolic demand because it's quite complicated. So if you're listening to this and thinking,"wow, every one of those system issues sounds like me", I want you to hear this clearly. It does not mean that you can't tolerate T3, and it does not mean your body's rejecting the medication. T3 is an essential molecule in your body. Everybody has it. Everybody who's alive has it. If you don't have it, you are not gonna stay alive for very long. So it's not that you can't tolerate the T3, it means you need a stepwise plan so that the T3 can work the way it's meant to work. And if you get these things right, you may find out that your T3 that your body naturally produces starts working again. So when we taper your caffeine, stabilize your sleep, your blood sugar, your nutrient status, your dosage, and your lab timing, everything changes, and suddenly you discover you're probably not intolerant to T3 at all. You just needed a more supportive environment for your metabolism to accelerate safely. It may be a slow process, particularly if you have extreme stress related issues, but it's not impossible. So if you're a clinician that's listening, I hope this gives you some reassurance. You are not failing your patients. The training that you received simply did not include this level of nuance, and the good news is that these issues are individually not that complicated or completely fixable. So in the next part of this series, I'm gonna talk about the medication side, which is how T3 and T4 interact, what happens when the dose is too low or too high, and maybe a little bit more details about how cortisol and insulin work together with T3. So just gonna say today about that, that another reason that T3 appears to fail is that your labs are not being interpreted with sufficient context because timing and physiology and pattern recognition may be missing, and clinicians are pushed towards adjustments that unintentionally worsen the symptoms because they're not aware of the pharmacology of these medications. And when that happens, T3 gets the blame, even though it's the process that is failing because it's perfectly possible to set things up to make T3 really transformative consistently for the long term and safe as well. So if you wanna go deeper right now, I have a few resources that I wanna tell you about. First of all, you can download my Core 5 Thyroid Lab Ordering Guide. This outlines the labs that I use in my practice to catch issues with standard thyroid panels that completely miss the T3 imbalances that people can have. This includes the total T3, reverse T3 ratio. It includes how to time your labs, and the link is gonna be in the show notes or you can go to danagibbsmd.com/lab-guide to get this free gift. It's a simple PDF, but it can change your life. It also has a link that you can give to your physician to some of my more physician focused educational materials that are also free. Second, if you're a patient who is looking for a structured roadmap or a clinician who wants to offer better care to your patients, I have online training specifically for either of you and signing up for the lab guide will get you on the notification list for these. So the Thyroid Clarity Checkup is my patient centered lab ordering symptom and analysis guide, and it's presented live with Q&A and direct contact with me. It also explains how to get the right labs at the right timing to figure out exactly what your thyroid status is, whether or not you're already taking thyroid medications. It also goes into your next steps and how to find a doctor who can help you make your recovery happen. And I find that consistently my method helps patients resolve their symptoms and get on with their best lives. I also have free physician education content on my webpage with deep dives into this topic and more, and this includes the intro to my annual comprehensive hormone course and the weekly discussion group that I host. All these resources are accessible from my main webpage, danagibbsmd.com and look for the tab that says physician resources. And if you're struggling, please don't give up. You can feel better. Your energy, your sleep, your clarity, your mood, they're all recoverable. You just need a plan that matches the way your body works. Alright everybody, I'll see you in part two.

23:46

Thank you for listening to this episode of Beyond the Thyroid. If you found this information valuable, it would mean so much to me to take a few seconds and give the podcast a five star review. It helps other people who need this information find the show and it's really easy. Just search and click on the name of the show, Beyond the Thyroid, and scroll to the bottom to ratings and reviews. I truly do read and appreciate. Remember, when it comes to hormones, there will always be more to discover, so follow the show so you get the next episode as soon as it's released. And if you or someone you care about needs a caring doctor to help figure out how to heal hormone problems that other doctors have dismissed, check out my website at www. danagibbsmd. com. And if you're not a physician, please keep in mind, while I'm a doctor, I'm not your doctor. The content of this podcast is my opinion and it's for educational and entertainment purposes only. This is not meant to be individual medical advice and you should consult your own physician for any medical issues or diagnoses that you may have. I look forward to continuing this journey with you beyond the thyroid.