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23 surprising symptoms of too much thyroid medication

November 23, 2022 7 min read

If you've been feeling a little off lately and can't quite put your finger on why you might want to check if you're taking too much thyroid medication.

Like many people who suffer from hypothyroidism (underactive thyroid gland), you're probably taking thyroid hormone replacement medication. While these medications help you manage your condition and provide much-needed relief from hypothyroid symptoms, taking too much can have undesirable side effects.

But how do you know if you're taking more thyroid hormone medication than you need? Here are 23 surprising symptoms of too much thyroid medication and what to do if you experience any of them.

What medications are used to treat hypothyroidism?

The thyroid gland is responsible for producing two hormones: triiodothyronine (active thyroid hormone - T3) and thyroxine (inactive thyroid hormone - T4). These hormones play an important role in regulating the body's metabolism. In a healthy thyroid gland, the T4 is converted into T3 so your body can use it.

When you have hypothyroidism, your thyroid gland doesn't produce enough thyroid hormones. Therefore, thyroid medication works by replacing the missing thyroid hormones. That's why the treatment is called thyroid hormone replacement therapy.

There are several types of thyroid hormone replacement medication. The most common one is levothyroxine, the synthetic version of the T4 thyroid hormone. Brand names for levothyroxine include Synthroid, Tirosint, and Levoxyl.

However, since levothyroxine only contains T4, it doesn't work for everyone. This is because some people have a hard time converting T4 to T3. In this case, thyroid medication that contains both T4 and T3 is the best option.

One such medication is natural desiccated thyroid (NDT), such as VitaliThy. It's made from pork or beef thyroid glands. It contains both T4 and T3, so it more closely resembles the hormone levels found in a healthy person's thyroid gland. Because of this, NDT may be more effective than levothyroxine for some people.

Another alternative is liothyronine (synthetic T3), which is sometimes used together with levothyroxine.

What are the symptoms of too much thyroid medication?

The symptoms of too much thyroid medication are a bit contradictory. If you are taking too much levothyroxine, you might actually get more hypothyroid. However, if you take too much liothyronine or too much NDT like Armour Thyroid, WP Thyroid, and VitaliThy, you might experience symptoms of hyperthyroidism.

The reason behind this paradoxical nature of thyroid hormone overdose is the fact that T3 is the active thyroid hormone.

Levothyroxine only contains the thyroid hormone T4, which is a prohormone for T3. If your body doesn't convert T4 into T3 properly and you increase your T4 dose, the ratio of T4 to T3 in your blood and tissues might get worse. As a result, you'll be more hypothyroid.

Here are 23 surprising symptoms of too much thyroid hormone medication:

1. Fatigue

If you are taking too much thyroid medication, you may eventually experience fatigue.

Too much thyroid medication can interfere with the body's ability to produce energy. It can cause your thyroid gland to be overactive and makes too many hormones. This will accelerate your metabolism and heart rate, causing you to feel tired and sluggish.

2. Weight gain or weight loss

Many underactive thyroid patients take thyroid medication in hopes of weight loss. But sometimes, the numbers on your scale might be going up instead of down.

Weight gain caused by too much thyroid medication most often occurs when you're taking levothyroxine. As explained above, levothyroxine contains only T4.

If your body can't convert that T4 to T3 well enough, the ratio of T3 to T4 thyroid hormone levels in your blood will be imbalanced. This caused you to be more hypothyroid.

To make things more complicated, the wrong dosage of thyroid medication may also cause rapid, unhealthy weight loss.

3. Irritability

Irritability is a symptom that is present when you have too much or not enough thyroid hormone. This means that you may experience it whether your thyroid medication dose is too high or too low. However, it tends to be associated with hyperthyroidism (overactive thyroid) and higher doses.

Keep in mind that, by itself, irritability isn't always a sign of thyroid replacement medication overdose. It can only be a sign if you experience other common symptoms.

4. Increased anxiety

Your thyroid gland produces thyroid hormones, which helps regulate metabolism, or the way your body convert food into energy.

But when your thyroid hormone level is too high, it'll speed up your metabolism and cause your entire sympathetic nervous system to be more active. Thus, taking thyroid hormone replacement drug in high doses can cause you to feel jittery and anxious.

5. Difficulty sleeping

Sleep problems or insomnia is one of the most common hyperthyroidism symptoms. Therefore, many thyroid patients who take too much thyroid medication may find it hard to get a restful night of sleep. This problem arose from irritability and the jittery feeling that overactive thyroid causes.

6. Increased heart rate

Among the most common symptoms of levothyroxine, overdose is increased heart rate.

If you have an excessive amount of thyroid hormone replacement medication in your system, it can cause an increased heart rate. This is because the thyroid hormone regulates the body's metabolism, and when there is too much of it in the bloodstream, it can cause the heart to race.

7. Irregular heart rhythm

Again, your metabolism will accelerate as your thyroid hormone levels increase. This can cause an irregular heartbeat or atrial fibrillation.

8. Heart palpitations

With increased heart rate and irregular heart rhythm, you'll likely experience palpitations. Heart palpitations, in simple words, are feelings of having a pounding heart. In some cases, it can be uncomfortable and may cause you to experience chest pain.

9. More frequent migraines

There's a link between thyroid disease and migraines. In fact, both too low and too high doses of thyroid hormone replacement can cause headaches and migraines.

10. Excessive thirst

If you find yourself eating and drinking more than usual, it might signal that the dose of your thyroid hormone medication is too high. Excess thyroid hormone replacement medication speeds up your metabolism, making you feel thirsty and hungry constantly.

11. Excessive urination

Increased urination is one of the most common symptoms of hyperthyroidism, so it also happens to hyperthyroid patients who take too much thyroid medication. Like most other symptoms, this has to do with your metabolism. When the thyroid hormone levels are high, the body's metabolism increases, and this can lead to increased urination.

12. Heat intolerance

Your thyroid regulates your body temperature. That's why those with thyroid disease may struggle with abnormal body temperature. When you have hypothyroidism, you may have cold intolerance. Your thyroid medication is supposed to bring your thyroid levels to a normal range, so you will no longer constantly feel cold.

But when your dose is too high, your thyroid gland may produce more hormones than your body needs, causing your temperature to rise. As a result, you might find yourself feeling more sensitive to heat.

13. Increased sweating

This is closely linked to heat intolerance. When you take too much thyroid medication, you'll likely sweat a lot.

14. Diarrhea or frequent bowel movements

When your metabolism goes into overdrive, your digestion will speed up, so food will not stay in your digestive system for a long time. This may lead to frequent bowel movements or even diarrhea. You may also notice looser stools.

15. Tremors

Just as excess thyroid hormone causes you to feel jittery and anxious, it can also lead to tremors. This happens because the signals that travel across your nerves speed up.

16. Menstrual Changes

Have you noticed changes to your menstrual cycle? Then it might be a sign that you need a lower dose of thyroid medication. High levels of thyroid hormone can lead to menstrual changes, such as lighter, shorter, or skipped periods.

In some cases, hyperthyroidism may also cause Amenorrhea, which is the absence of menstruation.

17. Fertility issues

Fertility issues are one of the most common symptoms of thyroid disorders, both hypothyroidism, and hyperthyroidism. Too much thyroid hormone can cause problems with ovulation and implantation, and it may also increase the risk of miscarriage.

18. Fever

As explained before, excess thyroid hormones can cause your body's temperature to rise. In many cases, this may lead to fever.

19. Hair loss

Hair loss may indicate that you're not taking the right dose of thyroid medication. This can sometimes be confusing since low thyroid medication can also cause hair loss. But in the case of high thyroid medication, your hair loss is accompanied by dry, brittle, and cracking hair.

20. Muscle weakness

A high dose of thyroid medication can gradually break down your muscle tissue. You'll notice this symptom when climbing stairs or lifting heavy objects feel difficult.

21. Difficulty concentrating

Just like how hypothyroidism causes brain fog, high levels of thyroid hormones due to too much thyroid medication can lead to poor concentration, memory lapses, and slower reaction time.

22. Nausea

Nausea and vomiting are signs that your dose of thyroid medication isn't right. There are a few possible connections between hyperthyroidism and nausea. One is that the excess hormone can cause an increase in metabolism, which can lead to feeling nauseated.

Another possibility is that the hormone can stimulate the digestive system, leading to increased stomach acid and nausea. Finally, hyperthyroidism can also cause anxiety and stress, which can also lead to feeling nauseated.

23. Elevated blood pressure

Both types of thyroid problems, hypothyroidism and hyperthyroidism, can result in high blood pressure. This means that the wrong dose of thyroid medication can eventually lead to hypertension.

How doctors test overmedication

Of course, experiencing the above symptoms doesn't always mean you're taking too much thyroid replacement medication. Therefore, to ensure you're overmedicated, your doctor may use a combination of tests.

For example, they may order a blood test that shows your thyroid stimulating hormone levels (TSH levels). When your thyroid stimulating hormone level is at the low end of the reference range (below o.5), your T4 and T3 hormones may be elevated. Thus, indicating that the dose of your thyroid medication is too high or that you are overmedicated.

What to do if you take too much thyroid medication

Although stopping your thyroid medication altogether may seem like a good idea, you should refrain from doing it. Abruptly stopping your medication may only cause other problems.

The first thing you want to do is to speak with your doctor. They'll likely adjust your thyroid medication dose or switch you to a different medication.

Sometimes, the problem lies in your body's inability to properly convert T4 to T3. So you won't experience any improvements with levothyroxine. And adding a higher dose of this synthetic T4 medication may be counterproductive and make you more hypothyroid.

In this case, your best option is natural desiccated thyroid (NDT), like VitaliThy. NDT supplements and medication contain T4 and T3 hormones, so it's more effective than T4-only medications.

The best thing is that you can buy desiccated thyroid online and have it shipped right to your door. If you're looking for an effective and safe way to treat hypothyroidism, give desiccated thyroid a try!

Wojciech Majda
Wojciech Majda

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