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June 26, 2023 9 min read

Did you know that nearly 20 million Americans suffer from thyroid disease? Levothyroxine, a synthetic thyroid hormone, is one of the most commonly prescribed medications for hypothyroidism. While it can effectively regulate your thyroid levels and improve your overall well-being, it's important to be aware of levothyroxine's side effects.

One such side effect that many people experience is irritability. Levothyroxine and irritability can go hand in hand due to the medication's impact on your body's hormone levels. As with any medication, different people will react differently to levothyroxine treatment, but if you do experience irritability or mood swings while taking it, know that you're not alone. Let's explore the connection between the medication and this emotional side effect.

What is levothyroxine?

Levothyroxine sodium is a synthetic version of the thyroid hormone thyroxine (T4). It's the standard medication doctors prescribe to help your thyroid get back on track if you have hypothyroidism, a condition in which the thyroid gland doesn't produce enough thyroid hormone. Your body needs thyroid hormone to function properly. Without it, you may experience fatigue, weight gain, and depression.

Aside from hypothyroidism, levothyroxine therapy is also prescribed for people with specific thyroid-related conditions, such as Hashimoto's thyroiditis, as well as those who have undergone thyroidectomy and those who need suppressive therapy to treat thyroid cancer.

Levothyroxine is typically administered orally in tablet form, taken once a day, usually in the morning on an empty stomach, and at least 30 minutes before any food, beverage (other than water), or other medications. The dosage of levothyroxine varies based on factors like age, body weight, the severity of your condition, and individual response to the medication. Your doctor will determine the optimal starting dose and make adjustments if necessary to maintain the right hormone levels in your blood.

How levothyroxine works

When experiencing hypothyroidism, the body doesn't produce adequate thyroid hormone levels required for numerous physiological processes. That's where levothyroxine, as a thyroid hormone medication, comes in. This medication mimics the role of T4 produced by the thyroid gland and improves the production of triiodothyronine (T3) - another critical thyroid hormone. By boosting hormone levels, levothyroxine restores balance and helps manage various symptoms such as fatigue, unexplained weight gain, and cold intolerance.

What are the side effects of levothyroxine?

While levothyroxine is a widely prescribed and well-tolerated medication when taken as directed, it's crucial to be aware of potential side effects. These can include nervousness, irritability, increased appetite, weight loss, difficulty sleeping, headaches, and excessive sweating. Most of these side effects, however, occur due to improper dosage, which can result in a state of hyperthyroidism.

Can hypothyroidism cause irritability?

Levothyroxine and irritability, what's the connection?

Is the inner grumpy cat taking over your mood lately? It could be worth having a chat with a healthcare professional to explore the possibility of thyroid hormone imbalances. Hypothyroidism, a condition where the thyroid gland does not produce enough crucial thyroid hormones, has the potential to negatively impact one's emotional well-being. One of these issues might be feeling extra irritated or short-tempered. This is usually because people with hypothyroidism often feel super tired, run-down, and foggy-brained, which can make anyone a bit cranky during day-to-day activities and interactions.

Now, getting annoyed every now and then doesn't automatically mean you have hypothyroidism. But if you're also dealing with other stuff like unexplained weight gain, always feeling tired, being sensitive to colds, or having dry skin, it's probably a good idea to see your healthcare provider and get your thyroid checked out.

Why do I feel irritated all the time, even with levothyroxine?

Feeling irritable all the time, even when you're on levothyroxine? It can be pretty frustrating. This medication is supposed to treat hypothyroidism and its symptoms, including irritability. Yet it's also possible that, in some cases, levothyroxine itself may contribute to feelings of irritability. This paradoxical situation can leave individuals searching for answers and explanations. Here are some insights into why one might still experience irritability while taking levothyroxine:

1. Wrong dosage

Dealing with irritability might have something to do with taking the wrong amount of levothyroxine. If you're taking too much levothyroxine, it could lead to hyperthyroidism – when your thyroid goes into overdrive – and feeling irritable is one of the side effects. On the flip side, if you're not taking enough levothyroxine, your hypothyroidism isn't getting properly treated, so your symptoms, like feeling cranky, stick around.

Finding the perfect Levothyroxine dosage for your body can sometimes be a bit of a trial-and-error process. Your healthcare provider will likely make adjustments based on blood tests, such as thyroid stimulating hormone (TSH) test, and your reported symptoms. During this time, it's important to be patient and keep an open line of communication with your doctor. Remember that it might take several weeks for your body to adjust to a new dosage, so your irritability may linger a bit longer until you reach the optimal balance.

2. T4 to T3 conversion

Levothyroxine provides synthetic T4 (inactive form) to your body, and for most people, this works well as their bodies efficiently convert T4 to T3 (active form). However, some individuals have difficulty with this conversion, leading to suboptimal T3 levels despite taking levothyroxine. 

3. Other health conditions

Irritability may be linked to various other underlying health issues beyond hypothyroidism. For instance, low levels of vitamin D, vitamin B12, or iron can contribute to mood imbalances. Hormonal imbalances, such as estrogen or testosterone deficiencies, might also play a role. Additionally, anxiety, depression, or chronic stress can significantly impact irritability. It's crucial to consider these possibilities and discuss them with your healthcare provider for further evaluation and potential management.

4. Lifestyle factors

Our daily routines, habits, and choices can greatly influence our mental and emotional well-being. Getting enough quality sleep, engaging in regular physical activity, and maintaining a well-balanced diet can help keep irritability in check. Stress management and relaxation techniques, such as meditation, deep breathing, or yoga, might be useful in addressing irritability as well. Assessing your lifestyle and making improvements where necessary could make a positive impact on your mood.

5. Levothyroxine absorption

To ensure the effectiveness of levothyroxine, proper absorption in your system is essential. However, certain medications, supplements (like calcium carbonate or iron), or even foods (like soy products) can interfere with its absorption. Make sure you're taking your medication on an empty stomach, ideally in the morning, and waiting at least 30 to 60 minutes before eating or drinking anything other than water. Discuss any other medications or supplements you're taking with your healthcare provider to avoid potential interactions that could be contributing to your irritability.

In summary, if you persistently feel irritable despite taking levothyroxine, it's essential to collaborate with your healthcare provider. They can help pinpoint the cause, make necessary adjustments, or consider alternative treatment options to better address your emotional well-being and overall health.

How can you manage or reduce irritability while taking levothyroxine?

If you're experiencing irritability during your levothyroxine treatment, there are several things you can do to manage and reduce it.

1. Monitoring and adjusting medication dosage

It's important to monitor and adjust your medication dosage to keep your irritability in check. This is especially true when taking levothyroxine, as the medication works to regulate thyroid hormone levels in the body. If your dosage is too high or too low, it can cause various symptoms, including irritability.

  • To ensure that you're on the right track with your medication dosage, consider the following tips:

  • Keep a detailed record of your symptoms and any changes you notice after adjusting your dosage.

  • Schedule regular appointments with your healthcare provider to discuss any concerns or questions you may have about your medication.

  • Be patient since finding the right dosage can take time and may require trial and error.

By staying vigilant about monitoring and adjusting your levothyroxine dosage as needed, you can help manage any irritability caused by fluctuations in thyroid hormone levels.

In addition to maintaining proper medication levels, there are also stress management techniques that can further help improve symptoms of irritability.

A pharmacist selling levothyroxine and natural desiccated thyroid (NDT)

2. Consider combination therapy or natural desiccated thyroid (NDT)

If you've tried other solutions, but irritability persists, discuss the possibility of combination therapy with your healthcare provider. This approach involves supplementing your synthetic T4 medication (Levothyroxine) with a synthetic T3 medication (liothyronine). The downside of doing this is that you need to buy two separate synthetic thyroid hormones.

Another option to consider is natural desiccated thyroid (NDT), which contains a mix of T4 and T3 hormones derived from animal sources. Many people prefer it because it already contains both thyroid hormones and is seen as a more "holistic" approach to hypothyroidism treatment. NDT is available in both medication and supplement forms. The most common NDT medications in the US are Armour Thyroid and NP Thyroid. You can also buy desiccated thyroid online, without a prescription, such as VitaliThy. This NDT supplement contains both T4 and T3, just like Armour Thyroid and NP Thyroid. Plus, it's free from lactose, gluten, fish, shellfish, and eggs, as well as artificial colors and flavors.

3. Stress management techniques

Aside from treating your hypothyroidism, another effective way to manage stress and improve mood is through relaxation techniques like deep breathing or meditation. Stress can worsen symptoms of an underactive thyroid, leading to increased irritability and anxiety. Incorporating relaxation techniques into your daily routine can help reduce stress levels and improve overall well-being.

Here are some methods you can do to manage your stress:

Deep breathing 

Deep breathing is an effective and simple technique to help manage stress and promote relaxation. By focusing on your breath and engaging in deep, mindful inhalations and exhalations, you can activate your body's relaxation response and reduce the impact of stress on your mind and body.

To practice deep breathing for stress management, follow these steps:

  • Find a quiet and comfortable space where you can sit or lie down. 

  • Close your eyes and take a moment to bring your attention to your breath. Notice the sensation of the air entering and leaving your body.

  • Take a slow, deep breath through your nose, filling your lungs with air. Allow your abdomen to expand as you inhale deeply.

  • Hold your breath briefly, then exhale slowly through your mouth, releasing any tension or stress as you release the breath.

  • Repeat this deep breathing pattern, inhaling deeply through your nose, holding briefly, and exhaling slowly through your mouth. Please focus on the sensation of your breath as it flows in and out of your body.

  • Try to lengthen your exhalations as you continue deep breathing, allowing them longer than your inhalations. This can help activate the relaxation response in your body.

  • Keep practicing deep breathing for a few minutes, allowing yourself to fully immerse in the rhythm and sensation of your breath. You can gradually increase the duration of your practice as you become more comfortable with the technique.


Yoga is a fantastic stress management technique that combines physical movement, breath control, and mindfulness to promote relaxation and overall well-being. It is an ancient practice that originated in India and has gained immense popularity worldwide for its numerous benefits for the mind, body, and spirit.

Incorporating yoga into your routine can effectively reduce stress levels and cultivate a sense of inner calm and balance.

Whether you attend yoga classes at a studio, follow online tutorials, or create your own practice at home, incorporating yoga into your routine can greatly benefit your stress management efforts. Start with beginner-friendly classes or sequences and gradually progress as you become more comfortable and confident in your practice.

4. Maintaining a healthy lifestyle

Maintaining a healthy lifestyle is essential for managing symptoms of an underactive thyroid, including irritability that may be exacerbated by levothyroxine or other forms of thyroid hormone replacement therapy. Incorporating simple habits like regular exercise and a balanced diet can make all the difference in improving overall well-being. Here are some ways to ensure you're on track:

  • Eat various nutrient-dense foods: A diet rich in fruits, protein sources, and healthy fats can help support your thyroid function and prevent deficiencies that may contribute to irritability.

  • Stay active: Regular physical activity helps with weight management and boosts mood and energy levels. Aim for at least 30 minutes of moderate-intensity exercise most days of the week.

  • Adequate Sleep: Prioritize getting enough sleep each night. Aim for 7-9 hours of quality sleep to support optimal mood regulation and minimize irritability.

By incorporating these healthy habits into your daily routine, you'll improve your overall health and manage irritability related to levothyroxine use more effectively. If you're still experiencing bothersome symptoms despite these measures, it's important to seek medical help from your healthcare provider.

5. Take levothyroxine correctly

Sometimes, the problem may not be in the thyroid medication itself but in the way you take it. Ensure you are taking levothyroxine as directed by your healthcare provider, on an empty stomach, and waiting 30 to 60 minutes before eating or drinking anything other than water. Avoid possible interactions with other medications or supplements that may interfere with absorption.

Conclusion: Irritability is one of the side effects of levothyroxine

Although levothyroxine is a commonly prescribed thyroid hormone replacement therapy, it can have side effects like any medication. One of the most common side effects reported by patients is irritability.

If you're experiencing irritability while taking levothyroxine, you must talk to your doctor about your symptoms. They can adjust your dose or switch you to a different medication that better suits your needs. In addition, they can rule out any other underlying causes of your irritability and ensure that you receive the appropriate treatment for your condition.

If you've gone through the process of adjusting your Levothyroxine dosage and have not experienced significant improvements in your symptoms, it could be worthwhile to explore alternative treatment options. One such option is natural desiccated thyroid (NDT), which is derived from the thyroid glands of porcine (pigs).

Unlike levothyroxine, which primarily contains the synthetic T4 hormone, NDT consists of a combination of both T4 and T3 hormones in their natural form. Some individuals may find that NDT better aligns with their body's needs and could experience symptom relief or improved well-being as a result. VitaliThy, a natural desiccated thyroid you can buy online, can be a great place to start. This NDT supplement contains porcine thyroid powder, spica prunellae siccus extract, ashwagandha extract, and selenium yeast. Each of these ingredients offers amazing benefits for your thyroid health.

Wojciech Majda
Wojciech Majda

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