Will I have Hashimotos forever?

Which Thyroid Medication is Best for Hashimoto’s

Which type of thyroid medication is best for Hashimoto’s? This is something I am asked all the time by my patients, in my support community, and in my Facebook community.

I first want to clarify that thyroid medications are not in the same family as harsh drugs and immunosuppressants used to treat other autoimmune conditions. Thyroid medications are a supplemental dose or replacement for a hormone that is necessary for you to live.

If your thyroid is too damaged from Hashimoto’s, you may need supplemental thyroid hormone for the rest of your life. My thyroid was ablated so I certainly do. This does not mean you have failed or that your condition cannot be reversed. Reversing Hashimoto’s means that your immune system is no longer attacking your thyroid, your antibodies have disappeared, and you are symptom-free. Now I’ll address the million-dollar question.

There is no “one size fits all” when it comes to thyroid medications and I don’t believe that there is one right choice for everyone.

What I have learned over the last fifteen years as both a thyroid patient as well as a thyroid-prescribing physician is that when it comes to thyroid medication it can be just as much an art as it is a science. You, the patient, need to listen to your body and share your experience with your doctor. And we, physicians, need to listen to our patients as well as look at their labs. I found over the years that how the patient is feeling can often tell more than what the labs say.

That being said, the first step in finding the right thyroid medication for you is to make sure that your doctor checks all of your thyroid levels.

The Thyroid, Hypothalamus, Pituitary Gland, Thyroid Hormones – Infographic – Amy Myers MD® Dr. Amy Myers July 17th, 2017 https://content.amymyersmd.com/article/thyroid-medication-hashimotos/ The Thyroid, Hypothalamus, Pituitary Gland, Thyroid Hormones – Infographic – Amy Myers MD®

Most doctors only check your Thyroid Stimulating Hormone (TSH) levels. If you are lucky, they will test your Free T4 levels to see if you are low on the storage form of thyroid hormones. What those two tests will not tell you is if you have difficulty converting T4 (the storage form of your thyroid hormones) to T3 (the active form), if you’re converting too much T4 to Reverse T3 (the hormone that “puts the brakes” on your metabolic processes), or if you have autoimmune thyroid disease. In short, TSH and T4 tests only tell you a small part of the story. If your treatment is based on only those two numbers, there is a good chance that your lab results will return to “normal” but your symptoms will not go away.

To get a complete picture of a patient’s thyroid health and medication needs, I would order all of the thyroid tests listed below. I also included here the ranges for each marker I’ve found to be optimal for both my patients and myself. You can find all of this information and more in my book, The Thyroid Connection.

TSH 1-2 UIU/ML or lower
Free T4 >1.1 NG/DL
Free T3 > 3.2 PG/ML
Reverse T3 > 10:1 ratio RT3:FT3
Thyroid Peroxidase Antibodies < 4 IU/ML or negative
Thyroglobulin Antibodies < 4 IU/ML or negative

Now that you’re armed with the insights from your lab results, you’re ready to look at all of your thyroid medication options to find the solution that best matches your needs. There are four main types of thyroid medications available for Hashimoto’s patients.

T4 Thyroid Medication

The most common Hashimoto’s treatment is synthetic T4 hormone medication, usually prescribed as the drug Synthroid® or Levoxyl®. Synthroid® is actually the most commonly prescribed drug in America, with 21.6 million prescriptions a month. 1

Synthroid® and Levoxyl® provide a steady dose of T4 (the storage form of thyroid hormones) for your body to convert into T3 (the active form), and come in a wide range of doses, making them very convenient. The downside of T4 medications is that, unlike your real thyroid, they don’t provide any T3. As we’ve discussed previously, many patients have difficulty converting T4 to T3, because of adrenal fatigue or nutritional deficiencies, meaning no matter how much T4 they take, their T3 levels will remain low and they’ll continue to experience symptoms. This is why it is so important for doctors to check not just TSH and T4 levels, but also T3. A patient’s lab results can look “fine”, yet they’ll still be low in the hormones that actually power all of their metabolic processes.

Another downside of synthetic medications is the inactive ingredients used. Thyroid hormones are prescribed in micrograms, so the amount of T4 in each pill is incredibly small. The rest of the pill is composed of inactive ingredients, synthetic colors, and fillers that vary by brand. Synthroid®, for example, contains lactose and cornstarch. 2 Tirosint is a T4 medication that includes only three inactive ingredients (gelatin, glycerin, and water). It is also produced in a dedicated facility to eliminate the risk of cross-exposure. This makes it a good alternative for those who are sensitive to foods and fillers.

There are also generic versions of Synthroid®, labeled levothyroxine. Their fillers vary by manufacturer and can sometimes contain allergens. Pharmacies can change manufacturers of generic medications without warning, so the inactive ingredients in your generic medications might vary month to month. What’s more, studies looking at levothyroxine show that their T4 doses are inconsistent across manufacturers and pharmacies. In a number of patients, I saw an improvement in lab results and a decrease in symptoms by changing from generic T4 to a brand name T4 medication. For this reason, I never recommend that anyone take generic T4 medications.

T3 Thyroid Medication

If you are a person who is not converting T4 into T3 very well, then T3 can be prescribed to supplement your T4 medication. There are several types of T3 medication, including preformed, synthetic T3 (frequently prescribed as Cytomel®), and compounded T3 medications, which are custom-prepared at the exact strength and dose requirements of the patient, as specified by their doctor.

As we covered in Part I of the series, T3 doesn’t remain active in your body for very long. Preformed T3 medications, such as Cytomel®, are only effective for about 10 hours, and must be taken twice a day. They provide a sudden burst and then decline in active thyroid hormones. I’ve found that many patients feel jittery shortly after taking them, as if they took a shot of espresso. They can then feel sluggish or tired as the effectiveness wears away.

Compounded T3 medication can be prepared in a time-release formula to avoid the hormone rollercoaster patients often experience on Cytomel® and similar preformed drugs. The downside of compounded medications is that some insurance companies won’t cover them, and compound pharmacies are not as common as regular pharmacies, so it might be difficult to find one near you. Fortunately, compounded medications are far less expensive than standard medications, so they are typically still affordable even without insurance, and most compounding pharmacies can ship your medications to you.

T4 and T3 Thyroid Medication

There are also a few different thyroid medication options that include both T4 and T3, namely desiccated thyroid medication (which comes from the dried thyroid glands of pigs) and compounded T4 and T3 medication.

Desiccated thyroid medications, such as Amour®, WP Thyroid®, and Nature-Throid®, provide the full range of thyroid hormones, including T4, T3, T2, and T1. This is particularly beneficial for those patients who have difficulty converting T4 to T3. It may also be helpful for hypothyroid patients trying to lose weight. According to some scientists, T2 is important for weight loss.

Desiccated thyroid medication also includes thyroglobulin (the binding protein that carries thyroid hormones through your bloodstream). Thyroglobulin slows the distribution of T3 throughout the body so that a single dose lasts the whole day.

In theory, the thyroglobulin could cause problems for those with Hashimoto’s as it could elevate your thyroglobulin antibodies. I say ‘in theory’ because I was taught this in my functional medicine training. However, I prescribed thyroid medication to over a thousand patients, yet I only actually saw this happen in four patients. So, while it is possible, clinically I would say it is very rare.

Desiccated thyroid medication is the most complete treatment option, and the most similar to your body’s natural thyroid process. I found it to be the right fit for many of my patients. Beyond my own clinical experience, multiple studies show that some patients prefer desiccated medication to T4-only treatment.

In a double-blind study where patients were given either desiccated thyroid medication or generic synthetic T4 for 12 weeks and then switched to the other drug, 49% of the patients preferred desiccated thyroid extract, 19% preferred synthetic T4, and 23% had no preference. 3 The patients also lost an average of 2.84 pounds while on desiccated thyroid hormone compared to the synthetic T4 drugs. Another study found that 78% of patients who switched from synthetic T4 treatment to desiccated medication preferred desiccated medication. 4

Like synthetic medications, desiccated thyroid medications also contain inactive ingredients that vary by brand. Armour® and Nature-Throid® each contain five or more inactive ingredients, including cellulose, and Armour® contains cornstarch. WP Thyroid®, which is the hypoallergenic version of Nature-Throid®, contains only two inactive ingredients—inulin and medium-chain triglycerides.

Each brand also differs in the variety of strengths it offers. WP Thyroid® and Armour® are available in eight different strengths (WP Thyroid® has more options for smaller doses, while Armour® has more options for higher doses), whereas Nature-Throid is available at 13 different strengths, ranging from low to high concentrations.

Many conventional doctors are reluctant to prescribe desiccated thyroid medication. They claim that the levels of thyroid hormones in them are inconsistent and unregulated. Although this was true decades ago, since the 1980’s the exact amount of each thyroid hormone in desiccated thyroid medications is regulated using the same standards as synthetic medications.

It is important to note that, while consistent and regulated, the T4 toT3 ratio in desiccated medications is lower than your natural T4 to T3 ratio (4.22:1 compared to 11:1). This is because pigs produce thyroid hormones at different ratios than humans do. Some patients taking desiccated thyroid medication who want to increase their T4 dose without increasing their T3 will need to supplement with a T4 medication. Personally, this is what I have to do.

For those who need extremely specific doses, compounded combination T4 and T3 medications offer the most flexibility. They are custom-formulated based on the patient to provide the exact strength and T4 to T3 ratio that they need. The drawback of compounded medications is that they do not contain other components of the thyroid. The desiccated porcine gland does—with T2, T1, and thyroglobulin.

Finding the Medication and Dose that Work for You

As you can see, there are many different options for thyroid medication, each with their own advantages and disadvantages. Many in the healthcare world like to frame it as a black and white issue, with conventional doctors who prescribe Synthroid® on one side, and alternative practitioners who prescribe desiccated medication on the other. In my experience, it’s not that clear cut, and what works for one person doesn’t necessarily work for another.

Finding the right treatment protocol can often be a case of trial and error. You’ll learn what medication or combination of medications, and at what doses, works best for you. As you go through this process, it’s important to work closely with your doctor and check your levels regularly. It’s also important to listen to your body. If thyroid levels are within “normal” range yet you still experience symptoms, you might not have found the perfect balance. You should speak with your doctor about continuing to fine-tune your protocol.

Going Beyond Medication: Treating the Root Cause of Thyroid Disease

Finding the right thyroid medication that works for you is very important. It will go a long way in helping you feel better. Still, remember that managing your thyroid levels through medication is only part of the process. The real work comes in identifying the underlying factors that caused your thyroid disease and making healthy lifestyle changes to remove them.

If you’re ready to tackle the underlying health issues that triggered your thyroid disease, you can read my book, The Thyroid Connection.

Remember that achieving optimal health is a journey, and each person’s path is unique. This is particularly true for Hashimoto’s, which can involve many different interconnected factors. Whether you’re just starting out or you’re well on your way, know that there are resources and support available. With enough knowledge and commitment, you can find the solution that works for you.

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Hypothyroidism

Hypothyroidism is a common condition where the thyroid doesn’t create and release enough thyroid hormone into your bloodstream. This makes your metabolism slow down. Also called underactive thyroid, hypothyroidism can make you feel tired, gain weight and be unable to tolerate cold temperatures. The main treatment for hypothyroidism is hormone replacement therapy.

Overview

What is hypothyroidism?

Hypothyroidism is a condition where there isn’t enough thyroid hormone in your bloodstream and your metabolism slows down.

Hypothyroidism happens when your thyroid doesn’t create and release enough thyroid hormone into your body. This makes your metabolism slow down, affecting you entire body. Also known as underactive thyroid disease, hypothyroidism is fairly common.

When your thyroid levels are extremely low, this is called myxedema. A very serious condition, myxedema can cause serious symptoms, including:

• A low body temperature.
• Anemia.
• Heart failure.
• Confusion.
• Coma.

This severe type of hypothyroidism is life-threatening.

In general, hypothyroidism is a very treatable condition. It can be managed with regular medications and follow-up appointments with your healthcare provider.

How does my thyroid work?

The thyroid gland is a small, butterfly-shaped organ located in the front of your neck just under the voice box (larynx). Picture the middle of the butterfly’s body centered on your neck, with the wings hugging around your windpipe (trachea). The main job of the thyroid is to control your metabolism. Metabolism is the process that your body uses to transform food to energy your body uses to function. The thyroid creates the hormones T4 and T3 to control your metabolism. These hormones work throughout the body to tell the body’s cells how much energy to use. They control your body temperature and heart rate.

When your thyroid works correctly, it’s constantly making hormones, releasing them and then making new hormones to replace what’s been used. This keeps your metabolism functioning and all of your body’s systems in check. The amount of thyroid hormones in the bloodstream is controlled by the pituitary gland, which is located in the center of the skull below the brain. When the pituitary gland senses either a lack of thyroid hormone or too much, it adjusts its own hormone (thyroid stimulating hormone, or TSH) and sends it to the thyroid to balance out the amounts.

If the amount of thyroid hormones is too high (hyperthyroidism) or too low (hypothyroidism), the entire body is impacted.

Who is affected by hypothyroidism?

Hypothyroidism can affect people of all ages, genders and ethnicities. It’s a common condition, particularly among women over age 60. Women are generally more likely to develop hypothyroidism after menopause than earlier in life.

What’s the difference between hypothyroidism and hyperthyroidism?

In hypothyroidism, the thyroid doesn’t make enough thyroid hormone.

The difference between hypothyroidism and hyperthyroidism is quantity. In hypothyroidism, the thyroid makes very little thyroid hormone. On the flip side, someone with hyperthyroidism has a thyroid that makes too much thyroid hormone. Hyperthyroidism involves higher levels of thyroid hormones, which makes your metabolism speed up. If you have hypothyroidism, your metabolism slows down.

Many things are the opposite between these two conditions. If you have hypothyroidism, you may have a difficult time dealing with the cold. If you have hyperthyroidism, you may not handle the heat. They are opposite extremes of thyroid function. Ideally, you should be in the middle. Treatments for both of these conditions work to get your thyroid function as close to that middle ground as possible.

Symptoms and Causes

What causes hypothyroidism?

Hypothyroidism can have a primary cause or a secondary cause. A primary cause is a condition that directly impacts the thyroid and causes it to create low levels of thyroid hormones. A secondary cause is something that causes the pituitary gland to fail, which means it can’t send thyroid stimulating hormone (TSH) to the thyroid to balance out the thyroid hormones.

Primary causes of hypothyroidism are much more common. The most common of these primary causes is an autoimmune condition called Hashimoto’s disease. Also called Hashimoto’s thyroiditis or chronic lymphocytic thyroiditis, this condition is hereditary (passed down through a family). In Hashimoto’s disease, the body’s immune system attacks and damages the thyroid. This prevents the thyroid from making and releasing enough thyroid hormone.

The other primary causes of hypothyroidism can include:

• Thyroiditis (inflammation of the thyroid).
• Treatment of hyperthyroidism (radiation and surgical removal of the thyroid).
• Iodine deficiency (not having enough iodine — a mineral your thyroid uses to make hormones – in your body).
• Hereditary conditions (a medical condition passed down through your family).

In some cases, thyroiditis can happen after a pregnancy (postpartum thyroiditis) or a viral illness.

What causes hypothyroidism in pregnancy?

In most cases, women with hypothyroidism during pregnancy have Hashimoto’s disease. This autoimmune disease causes the body’s immune system to attack and damage the thyroid. When that happens, the thyroid can’t produce and release high enough levels of thyroid hormones, impacting the entire body. Pregnant people with hypothyroidism may feel very tired, have a hard time dealing with cold temperatures and experience muscles cramps.

Thyroid hormones are important to fetal development. These hormones help develop the brain and nervous system. If you have hypothyroidism, it’s important to manage your thyroid levels during pregnancy. If the fetus doesn’t get enough thyroid hormone during development, the brain may not develop correctly and there could be issues later. Untreated or insufficiently treated hypothyroidism during pregnancy may lead to complications like miscarriage or preterm labor.

Does birth control affect my thyroid?

When you’re on birth control pills, the estrogen and progesterone inside of the pills can affect your thyroid-binding proteins. This increases your levels. If you have hypothyroidism, the dose of your medications will need to be increased while you’re using birth control pills. Once you stop using birth control pills, the dosage will need to be lowered.

Can hypothyroidism cause erectile dysfunction?

In some cases, there can be a connection between untreated hypothyroidism and erectile dysfunction. When your hypothyroidism is caused by an issue with the pituitary gland, you can also have low testosterone levels. Treating hypothyroidism can often help with erectile dysfunction if it was directly caused by the hormone imbalance.

What are the symptoms of hypothyroidism?

The symptoms of hypothyroidism usually develop slowly over time – sometimes years. They can include:

• Feeling tired (fatigue).
• Experiencing numbness and tingling in your hands.
• Having constipation.
• Gaining weight.
• Experiencing soreness throughout your body (can include muscle weakness).
• Having higher than normal blood cholesterol levels.
• Feeling depressed.
• Being unable to tolerate cold temperatures.
• Having dry, coarse skin and hair.
• Experiencing a decrease sexual interest.
• Having frequent and heavy menstrual periods.
• Seeing physical changes in your face (including drooping eyelids, as well as puffiness in the eyes and face).
• Having your voice become lower and hoarser.
• Feeling more forgetful (“brain fog”).

Will hypothyroidism make me gain weight?

If your hypothyroidism is not treated, you could gain weight. Once you are treating the condition, the weight should start to lower. However, you will still need to watch your calories and exercise to lose weight. Talk to your healthcare provider about weight loss and ways to develop a diet that works for you.

Diagnosis and Tests

How is hypothyroidism diagnosed?

It can actually be difficult to diagnose hypothyroidism because the symptoms can be easily confused with other conditions. If you have any of the symptoms of hypothyroidism, talk to your healthcare provider. The main way to diagnose hypothyroidism is a blood test called the thyroid stimulating hormone (TSH) test. Your healthcare provider may also order blood tests for conditions like Hashimoto’s disease. If the thyroid is enlarged, your provider may be able to feel it during a physical exam during an appointment.

Management and Treatment

How is hypothyroidism treated?

In most cases, hypothyroidism is treated by replacing the amount of hormone that your thyroid is no longer making. This is typically done with a medication. One medication that is commonly used is called levothyroxine. Taken orally, this medication increases the amount of thyroid hormone your body produces, evening out your levels.

Hypothyroidism is a manageable disease. However, you will need to continuously take medication to normalize the amount of hormones in your body for the rest of your life. With careful management, and follow-up appointments with your healthcare provider to make sure your treatment is working properly, you can lead a normal and healthy life.

What happens if hypothyroidism is not treated?

Hypothyroidism can become a serious and life-threatening medical condition if you do not get treatment from a healthcare provider. If you are not treated, your symptoms can become more severe and can include:

• Developing mental health problems.
• Having trouble breathing.
• Not being able to maintain a normal body temperature.
• Having heart problems.
• Developing a goiter (enlargement of the thyroid gland).

You can also develop a serious medical condition called myxedema coma. This can happen when hypothyroidism isn’t treated.

Will I have the same dose of medication for hypothyroidism my entire life?

The dose of your medication can actually change over time. At different points in your life, you may need to have the amounts of medication changed so that it manages your symptoms. This could happen because of things like weight gain or weight loss. Your levels will need to be monitored throughout your life to make sure your medication is working correctly.

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Prevention

Can hypothyroidism be prevented?

Hypothyroidism cannot be prevented. The best way to prevent developing a serious form of the condition or having the symptoms impact your life in a serious way is to watch for signs of hypothyroidism. If you experience any of the symptoms of hypothyroidism, the best thing to do is talk to your healthcare provider. Hypothyroidism is very manageable if you catch it early and begin treatment.

Living With

Are there any foods I can eat to help my hypothyroidism?

Most foods in western diets contain iodine, so you do not have to worry about your diet. Iodine is a mineral that helps your thyroid produce hormones. One idea is that if you have low levels of thyroid hormone, eating foods rich in iodine could help increase your hormone levels. The most reliable way to increase your hormone levels is with a prescription medication from your healthcare provider. Do not try any new diets without talking to your provider first. It’s important to always have a conversation before starting a new diet, especially if you have a medical condition like hypothyroidism.

Foods that are high in iodine include:

• Eggs.
• Dairy products.
• Meat, poultry and seafood.
• Edible seaweed.
• Iodized salt.

Work with your healthcare provider or a nutritionist (a healthcare provider who specializes in food) to craft a meal plan. Your food is your fuel. Making sure you are eating foods that will help your body, along with taking your medications as instructed by your healthcare provider, can keep you healthy over time. People with thyroid condition should not consume large amounts of iodine because the effect may be paradoxical (self-contradictory).

Can hypothyroidism go away on its own?

In some mild cases, you may not have symptoms of hypothyroidism or the symptoms may fade over time. In other cases, the symptoms of hypothyroidism will go away shortly after you start treatment. For those with particularly low levels of thyroid hormones, hypothyroidism is a life-long condition that will need to be managed with medication on a regular schedule.

Levothyroxine: 7 things you should know

Medically reviewed by Carmen Pope, BPharm. Last updated on March 31, 2023.

1. How it works

• Levothyroxine is a man-made form of thyroxine, a hormone that is produced naturally in the body by the thyroid gland.
• Levothyroxine replaces missing thyroxine in people whose thyroid glands do not produce enough thyroxine naturally.
• Thyroid hormones (such as thyroxine) play a vital role in our normal growth and development, and the maturation of our brain, spinal cord, nerves, and bone. Thyroid hormones help cells function and are also involved in their breakdown. They also help regulate our moods, reproductive function, metabolism, and gastrointestinal function.
• Levothyroxine is generally taken life-long when used to treat hypothyroidism (low thyroid levels) unless the cause is transient.

2. Upsides

• Used for the treatment of hypothyroidism (low thyroxine levels in the body). Replaces or supplements low or missing thyroxine and maintains normal intellectual and physical growth and development.
• In children born with hypothyroidism, levothyroxine rapidly restores thyroid levels to normal, preventing detrimental effects on intellectual and physical development.
• Levothyroxine is recommended by American guidelines as the preferred hormone for hypothyroidism. It is effective for all causes of hypothyroidism, except transient hypothyroidism caused by subacute thyroiditis (an inflammatory disease of the thyroid most likely caused by a virus).
• May also be used in the management of goiter and some thyroid cancers.
• Generic levothyroxine is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• May increase heart rate, cause arrhythmias (palpitations), precipitate angina, and have other adverse effects on the heart.
• Headache, hair loss, flushing, diarrhea, and menstrual irregularities in women are also reasonably common.
• May cause weight loss; however, thyroxine should not be used for the sole purpose of treating obesity as its risks far outweigh any benefits when used in people with normal thyroid function.
• There is a fine line between having too much thyroxine resulting in toxicity, and having too little, meaning that it is ineffective.
• Levothyroxine has been associated with a decrease in bone mineral density when used long-term, resulting in an increased risk of fractures.
• Should not be used in people whose adrenal glands are not functioning properly or with thyrotoxicosis (high levels of thyroid hormone) or when TSH levels are suppressed and T3 and T4 levels are normal.
• May not be suitable for people with cardiovascular disease or clotting disorders. Contraindicated following a heart attack (myocardial infarction).
• May not be suitable for women who are intending to become pregnant or during pregnancy or breastfeeding. It should not be used for the treatment of male or female infertility unless it is associated with hypothyroidism.
• Interacts with several other medications including amiodarone, anticoagulants, antidepressants, and digoxin. Foods such as soybean flour (found in infant formula), cottonseed meal, walnuts, and dietary fiber can decrease the absorption of levothyroxine.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Levothyroxine replaces missing thyroxine and is the preferred medicine to treat hypothyroidism. The dosage of levothyroxine needs to be tailored for each individual and there is a fine line between taking too much thyroxine and toxic side effects, and having too little, resulting in compromised functioning.

5. Tips

• Take on an empty stomach, at least 30 to 60 minutes before food. Several foods, including fiber, soy, coffee, and grapefruit juice can interfere with absorption. Supplements that contain iron and calcium may affect the absorption of levothyroxine (separate administration by 4 hours).
• Dosages should be titrated every 6 to 8 weeks under a doctor’s advice.
• Take thyroxine EXACTLY as directed by your doctor. Taking too much can result in toxicity and potentially fatal side effects; taking too little may mean that you are not taking enough to supplement your low thyroid levels. Do not discontinue or take any other dose without your doctor’s advice.
• Swallow capsules whole; do not cut, crush, or attempt to dissolve them in water.
• The Levoxyl-branded tablet may rapidly swell and disintegrate, and cause choking or gagging if it becomes stuck in your throat. Take it with a full glass of water, but talk with your doctor should you have difficulty swallowing it.
• Tell your doctor if you experience a rapid or irregular heart rate, chest pain, or shortness of breath. Also discuss any other unusual symptoms such as excessive sweating, leg cramps, irritability, sleeplessness, headache, tremors, changes in appetite or weight, menstrual irregularities, or skin rashes.
• Rarely, partial hair loss may occur during the first few months of treatment, but this is usually temporary.
• Regular blood tests are usually needed.
• Children may need intensive monitoring to prevent over or under-dosage as both can have detrimental effects on development. The dosage of levothyroxine may need adjusting during pregnancy.

6. Response and effectiveness

• 40-60% of orally administered levothyroxine is absorbed; the majority from the jejunum and upper ileum of the gastrointestinal tract. Absorption is increased when levothyroxine is taken on an empty stomach.
• May take several weeks for an improvement in symptoms to be seen and up to 4 to 6 weeks for peak blood levels to be reached.
• Absorption may be decreased with malabsorption syndromes and with certain foods such as soy-based infant formula.

7. Interactions

Medicines that interact with levothyroxine may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with levothyroxine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with levothyroxine include:

• amiodarone or other medications that affect iodine, such as radioactive iodine
• amphetamines, such as dexamphetamine or phentermine
• anticoagulants, such as warfarin
• anticonvulsants such as carbamazepine, phenobarbital, or phenytoin
• antidepressants, such as sertraline or anti-anxiety medications
• aspirin
• ciprofloxacin
• estrogens and oral contraceptives
• heart medications, such as digoxin, metoprolol, or propranolol
• HIV medications (eg, atazanavir, indinavir, ritonavir, or saquinavir)
• medications for diabetes, including insulin
• medications that can affect the absorption of levothyroxine, such as antacids, calcium carbonate, cholestyramine, iron, orlistat sucralfate, sevelamer, or proton pump inhibitors
• rifampin.

Note that this list is not all-inclusive and includes only common medications that may interact with levothyroxine. You should refer to the prescribing information for levothyroxine for a complete list of interactions.

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Related treatment guides

• Hashimoto’s disease
• Underactive Thyroid
• Hypothyroidism, After Thyroid Removal
• Myxedema Coma
• TSH Suppression
• Thyroid Suppression Test

References

• Levothyroxine. Revised 02/2023. XLCare Pharmaceuticals, Inc. https://www.drugs.com/pro/levothyroxine.html

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use levothyroxine only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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