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June 28, 2023 9 min read

If you are taking levothyroxine for your thyroid condition, it's important to be aware of the potential side effects of this medication. Levothyroxine is a synthetic hormone used to replace or supplement the natural thyroid hormone in your body. While it can effectively treat hypothyroidism and other thyroid disorders, it can also cause unpleasant side effects.

Some of the levothyroxine's most common side effects include weight changes, hair loss, headaches, anxiety, insomnia, and gastrointestinal issues such as diarrhea or constipation. It is important to note that only some people taking levothyroxine will experience these side effects, which may vary in severity from person to person.

What is levothyroxine?

The most common side effects of levothyroxine

So, you're taking levothyroxine? Commonly known under the brand name 'Synthroid,' levothyroxine is the synthetic form of the T4 thyroid hormone that is used to replace or supplement the thyroid hormones in your body. It's often prescribed for individuals with an underactive thyroid gland (hypothyroidism). The thyroid gland is responsible for producing hormones that regulate metabolism, energy levels, and growth. Insufficient amounts of thyroid hormones can result in fatigue, weight gain, hair loss, and other adverse symptoms.

Levothyroxine serves as a medication that replenishes or supplements the missing thyroid hormones in your system, promoting balanced metabolism and regulated energy levels. Available in various doses, this medication's dosage depends on the severity of your condition. Factors such as age, weight, and medical history are considered by your healthcare provider when determining the appropriate dosage for you.

In addition to treating an underactive thyroid gland, levothyroxine may also be prescribed for other thyroid-related conditions. For example, it may be used to treat thyroid cancer. In these cases, levothyroxine can help suppress the production of thyroid-stimulating hormones (TSH), which may aid in preventing cancer recurrence or growth. Another thyroid-related condition that may be treated with levothyroxine therapy is an enlarged thyroid gland (goiter).

Now that you understand levothyroxine and its potential side effects, let's move on to how it works.

How does levothyroxine work?

As mentioned above, levothyroxine works by replacing the thyroid hormone in your body and helps regulate your metabolism if you have hypothyroidism.

Levothyroxine gets absorbed through your small intestine and enters your bloodstream. Once it reaches your cells, it binds to specific receptors on their surface. It initiates a series of chemical reactions that increase cellular activity. This means your body starts burning more calories, producing more heat, and consuming more oxygen to keep up with the increased metabolic demand.

The effects of levothyroxine are not immediate; they can take weeks or months to fully kick in. During this time, you may experience mild side effects such as headache, nausea, fatigue, or irritability. These symptoms usually go away on their own as your body adjusts to the new thyroid hormone levels.

What are the most common side effects of levothyroxine?

Though levothyroxine is typically safe and effective in treating an underactive thyroid gland, it's essential to be aware of the potential side effects. Some common side effects may include:

1. Sweating

Sweating is one of levothyroxine's most common side effects, and it's not fun. It might make you feel like you're constantly running a marathon. Here are some things to keep in mind about sweating when taking this medication:

  • Sweating may occur more frequently or severely if your levothyroxine dosage is too high.

  • Staying hydrated is important, especially if you're experiencing excessive sweat.

  • Wearing lightweight, breathable clothing and staying in cool environments can help alleviate discomfort.

Levothyroxine side effects can vary from person to person, but sweating is definitely one that many people experience.

2. Heat intolerance

Feeling uncomfortable in hot environments is common for many people taking levothyroxine, and you may find yourself experiencing heat intolerance. This side effect occurs because levothyroxine increases your metabolism, causing your body to produce more heat than usual. As a result, you might feel hot or even start sweating when the temperature around you rises slightly.

Heat intolerance can be frustrating and make it difficult to enjoy outdoor activities during warmer months. To minimize this side effect, wear light clothing that allows air circulation, use fans or air conditioning as needed, and avoid direct sunlight whenever possible. Additionally, drinking plenty of water throughout the day will help keep your body cool and hydrated.

3. Anxiety

If you're experiencing anxiety while taking levothyroxine sodium, it may feel like a constant worry or unease that can be difficult to shake off. This is a common side effect of the medication, and it can be caused by the changes in hormone levels that occur when you start taking levothyroxine. Other symptoms accompanying anxiety include restlessness, irritability, difficulty sleeping, and racing thoughts. To help manage your anxiety while taking levothyroxine, there are several things you can try:

  • Practice relaxation techniques such as deep breathing, meditation, or yoga

  • Engaging in aerobic exercises can help release endorphins and reduce anxiety. Consider activities such as brisk walking, jogging in place, jumping jacks, or dancing to your favorite music

  • Talk with your doctor about adjusting your dosage or switching to a different medication

  • Seek professional counseling if your anxiety is severe or interfering with daily life.

It's important to note that if you experience chest pain or an allergic reaction while taking levothyroxine, seek immediate medical attention.

4. Constipation

To alleviate constipation while taking levothyroxine tablets, you should increase your fiber intake through foods like fruits and vegetables or try over-the-counter remedies such as stool softeners or laxatives. Levothyroxine doses can sometimes cause constipation as a side effect, so taking steps to prevent discomfort is important. Taking levothyroxine on an empty stomach at least 30 minutes before eating is recommended, as food can interfere with its absorption.

If increasing fiber intake and over-the-counter remedies don't improve your symptoms, talk to your doctor about other options. They may suggest adjusting your levothyroxine dose or prescribing medication for constipation relief.

5. Diarrhea

Managing diarrhea while taking levothyroxine can involve incorporating probiotics and staying hydrated to prevent discomfort. Levothyroxine tablets may cause diarrhea, particularly when taken in high doses or when the drug interacts with other medications. If you experience this side effect, staying hydrated by drinking plenty of fluids is important. Try using probiotics to help regulate your digestive system. Additionally, it may be helpful to avoid certain foods that can irritate the stomach, such as fatty or spicy dishes.

6. Hair loss

While levothyroxine treats thyroid-related hair loss, it can also ironically cause hair loss in some individuals. This side effect is not uncommon and may occur due to changes in your thyroid hormone levels. Typically, hair loss associated with levothyroxine use is temporary and will resolve once your body adjusts to the medication.

It's important to note that not everyone who takes levothyroxine will experience hair loss.

7. Headache

When experiencing headaches as a side effect of levothyroxine, there are some steps you can take to alleviate the discomfort. First, stay hydrated throughout the day, as dehydration can often cause headaches. Secondly, use over-the-counter pain relievers like ibuprofen or acetaminophen to manage the pain.

Finally, try relaxation techniques such as deep breathing exercises or meditation to help ease tension and reduce headache frequency.

8. Changes in menstrual periods

If you're a woman taking levothyroxine, it's important to be aware that changes in menstrual periods can occur, such as heavy or irregular menstrual periods. This is because levothyroxine affects the thyroid gland, which plays a role in regulating menstrual cycles.

9. Irregular heartbeats

Irregular heartbeats are another potential side effect of this medication that requires attention. This might occur if your dose of levothyroxine is too high.

Taking too high a dose of levothyroxine can lead to hyperthyroidism (overactive thyroid), which in turn causes fast or irregular heartbeats. If you experience palpitations or chest discomfort while taking this medication, report it to your doctor immediately.

Some tips for managing irregular heartbeats caused by levothyroxine include:

  • Avoiding caffeine and alcohol

  • Practicing relaxation techniques such as deep breathing exercises.

10. Weight changes

One potential change you may notice while taking levothyroxine is fluctuations in your weight. Depending on the dose of levothyroxine prescribed to you, you might experience weight loss or gain. However, it's essential to understand that these changes are not permanent and can be managed.

Sometimes, a higher levothyroxine dosage can lead to significant weight loss. In contrast, a lower dosage may result in weight gain.

For many hypothyroid patients, weight loss is usually the desired effect of levothyroxine. However, if you lose a lot of weight too rapidly, it might not be healthy. Thus, make sure to talk to your doctor if you think something is abnormal. It's important to keep in mind that levothyroxine is not a medication to treat obesity.

11. Tremors

Tremors refer to involuntary movements or shaking in your hands, arms, legs, or other body parts. Tremors can occur when there is too much thyroid hormone in your system because you take high doses of levothyroxine for an extended period.

12. Bone loss

Bone loss is a commonly reported side effect of levothyroxine, especially in postmenopausal women with a higher risk of developing osteoporosis. The drug works by increasing metabolism, which increases the bones' breakdown. This means that calcium gets released into the bloodstream faster than it can be replaced, decreasing bone density.

To combat this side effect, your doctor may recommend taking calcium supplements or incorporating more calcium-rich foods into your diet. Calcium carbonate is one supplement shown to help reduce bone loss caused by levothyroxine. However, following your doctor's instructions regarding the dosage and timing of supplements is important, as taking too much calcium can also lead to negative health effects. With proper monitoring and management, you can help prevent bone loss while still benefiting from using levothyroxine.

13. Trouble sleeping

Difficulty falling asleep may affect your nightly routine while taking levothyroxine, leaving you restless and sleepy in the mornings. Trouble sleeping is one of the most common side effects of this medication. Here are three ways to improve your sleep quality:

  • Establish a bedtime routine: Going to bed at the same time every night and following a relaxing pre-sleep ritual can help signal your body that it's time to wind down.

  • Limit screen time before bed: The blue light emitted by electronic devices can interfere with your body's melatonin production, making it harder to fall asleep.

  • Avoid caffeine and alcohol: Both substances can disrupt sleep patterns and cause restlessness.

These simple changes can make a big difference in your ability to get a good night's rest while taking levothyroxine.

14. Irritability

Suppose you've been taking levothyroxine for a while. In that case, you may have noticed that irritability is one of the most common side effects. This can be frustrating and difficult to deal with, especially if you're already dealing with other symptoms of an underactive thyroid.

It's important to remember that irritability is a known side effect of levothyroxine, and it's not something you're doing wrong. If you feel more irritable than usual, take deep breaths and stay calm. If the irritability persists, you should also talk to your doctor about adjusting your dosage or switching to a different medication.

15. Allergic reaction

In rare cases, individuals may experience an allergic reaction to levothyroxine. This can manifest as hives, difficulty breathing, skin rash, or swelling of the face, lips, tongue, or throat. If you suspect an allergic reaction, seek medical attention immediately.

What should I do if I continue to experience the side effects of levothyroxine?

If you continue to experience side effects from levothyroxine even after adjusting the dosage and employing various measures to mitigate them, it may be worth considering alternatives to your current medication.

One option is to integrate liothyronine, a synthetic T3 hormone, into your regimen. T3 is the active form of thyroid hormone, and by adding it, you may be able to better balance your thyroid hormone levels. This can help reduce ongoing side effects.

Alternatively, natural desiccated thyroid (NDT) might be a more suitable choice for those who prefer a more comprehensive treatment without relying solely on synthetic thyroid hormones. NDT is derived from the thyroid glands of pigs and contains a mixture of both T3 and T4 hormones.

The presence of both hormones in NDT can provide a more balanced approach to treating hypothyroidism. It can potentially be more effective in addressing symptoms such as fatigue, weight gain, and depression by offering a closer representation of the body's natural thyroid hormone production. Additionally, NDT may help some patients who have difficulty converting the synthetic T4 hormone found in levothyroxine into the active T3 form in their bodies.

NDT is available in the form of medication, which requires prescriptions. Some of the most popular include NP Thyroid, Armour Thyroid, Nature-Throid, and WP Thyroid. In addition, you can buy desiccated thyroid online in the form of supplements, such as VitaliThy.

Conclusion: levothyroxine side effects and how to manage them

While levothyroxine is a widely used and effective medication for treating hypothyroidism, some individuals may experience side effects despite adjusting their dosages and implementing various measures to alleviate them. Common side effects include headache, nausea, fatigue, or irritability, among others.

To manage these side effects, it's crucial to work closely with your healthcare provider and monitor your thyroid hormone levels regularly. Dosage adjustments, lifestyle changes, and proper administration of levothyroxine can potentially minimize or resolve these symptoms.

However, if the side effects persist despite these efforts, considering alternative treatments, such as natural desiccated thyroid (NDT), might be advantageous. NDT, derived from pig thyroid glands, contains a combination of T3 and T4 hormones, providing a more balanced approach to thyroid hormone replacement therapy. This comprehensive treatment has the potential to be more effective in addressing hypothyroidism symptoms and reducing side effects associated with levothyroxine.

One great option to try is VitaliThy, a natural desiccated thyroid you can buy online.

Wojciech Majda
Wojciech Majda

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