Is levothyroxine a hormone? Will there be any side effects if taken for a long time?

A friend told Huazi that after she suffered from hypothyroidism, the doctor asked her to take levothyroxine every day and she could not stop taking it. She asked Huazi whether levothyroxine was a hormone and whether long-term use would have side effects.

Hua Zi said that although levothyroxine is a hormone, it is different from the hormones we usually refer to. What we call hormone abuse refers to glucocorticoids, which can cause harm to the body when used for a long time. However, levothyroxine is not a glucocorticoid and is very safe for the human body when used reasonably and for a long time.

1. Why can’t levothyroxine be stopped?

There are two types of thyroid hormones in the human body, one is tetraiodothyronine (T4) and the other is triiodothyronine (T3). T3 is the main one that exerts physiological activity.

Levothyroxine is the most commonly used substitute for thyroid hormone in the human body. In terms of physiological activity and chemical properties, levothyroxine is completely consistent with the body's natural T4. After entering the human body, it will be converted into T3 to exert its physiological effects.

Therefore, when our own thyroid hormone is insufficient, reasonable supplementation of levothyroxine will not cause adverse effects on the body, because levothyroxine is the body's own "self".

There are many causes of hypothyroidism, the most common of which are Hashimoto's thyroiditis, thyroid tumors, thyroid surgery, radioactive iodine treatment, etc. These diseases can cause permanent damage to the thyroid gland, so hypothyroidism in most people cannot be reversed and requires lifelong replacement therapy, taking levothyroxine every day and cannot be discontinued.

Reasonable use of levothyroxine can simulate the secretion of human thyroid hormones without causing any impact on health. Moreover, levothyroxine will not damage liver and kidney function during metabolism, so it is very safe.

2. Do not take too much or too little levothyroxine

Thyroid hormones are hormones responsible for human growth, development, and metabolism, and the role of levothyroxine is to replace the insufficient thyroid hormone secreted by the human body. When taking it, be careful not to take too much or too little.

If taken in excess, it will cause hyperthyroidism (tachycardia), palpitations, facial flushing, sweating, headache, insomnia, sudden weight loss and other symptoms. In severe cases, it can lead to malignant arrhythmias.

If you do not take enough, the symptoms of hypothyroidism will be difficult to relieve, and you will experience chills, fatigue, slow reaction, depression, dry skin, etc. Hypothyroidism can also cause elevated blood lipids and bradycardia, and in severe cases, respiratory failure and heart failure.

3. What should I pay attention to when taking levothyroxine?

The best time to take levothyroxine is on an empty stomach half an hour before breakfast. Take the daily dose with water at one time. However, modern life is busy, and if you cannot leave enough time for fasting in the morning, you can also take the medicine on an empty stomach before going to bed.

The half-life of levothyroxine is 7 days. After taking the medicine regularly every day, the blood concentration will reach a stable "plateau value". If you occasionally miss a dose, the relevant guidelines recommend taking a double dose the next day.

However, some patients will experience symptoms of hyperthyroidism when taking double doses. Therefore, in actual application, if you only miss one day, you do not need to double the dose the next day, and you can take the normal dose, which will not affect the treatment. However, if you miss multiple days in a row, you need to take double the dose for multiple consecutive days until you make up for the missed dose.

To sum up, although levothyroxine is a hormone, it will not cause harm to the human body when used reasonably. People with hypothyroidism need lifelong replacement therapy and cannot stop taking the medicine. When taking the medicine, you need to choose the dosage that suits you according to your condition and under the guidance of a doctor. You cannot take more or less. If you have any questions about the use of the medicine, please consult a doctor and pharmacist. I am pharmacist Huazi, welcome to follow me and share more health knowledge.