Synthroid (Thyroxine)

Synthroid (levothyroxine sodium) tablets, for oral use is a prescription, man-made thyroid hormone that is used to treat a condition called hypothyroidism. It is meant to replace a hormone that is usually made by your thyroid gland.
Active Ingredient: Thyroxine
Dosage Form: Tablet
Dosage: 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg, 300 mcg Tablet;
Minimum Market Price: 0.1 $

General Information

Levothyroxine Sodium is the first commercial synthetic medicine for treatment of thyroid gland dysfunction in the USA which was firstly presented at the market in 1955 under the name Synthroid by Laboratory Flint. This medicine has a long story of medical use in the USA and at the international level, and for a long time it was the most popular medicine to combat hypothyroidism. Figures show that this brand provided 85% of the general sales of Levothyroxine and the revenues of medicine sale make $600 Mio. Among sportspeople, however, the medicine Cytomel is more popular because it’s faster and more effective. As this remedy is considered as a weaker medicine of slower action, for achievement of similar results it’s necessary to take it during a longer period of time.

Synthroid (Levothyroxine 50 mcg) has a quite long and difficult history. Several years after the creation of this drug it has achieved monopoly in the market. In the 1980th years, however, generics of Levothyroxine Sodium begin to appear. After that in 1986 the Flint company financed special researches in the Scientific Centre of California. It has been made to show that synthroid generic has more potent therapeutic action than its generics. The research was ended in 1990 and in fact has found that unlicensed drugs have equal efficiency. In the contract there was a even a reservation that for the publication of this research it’s necessary to receive an approval from the Flint company. Lawsuits for the publication have started. Even after the Flint laboratory has been sold to the Boots company which was sold later to the company called Knoll, the unveiling of the research results was constantly postponed. Finally the research has been published in 1997. After this the collective claim about the lack of information, which forced patients to overpay 2-3 times for the medicine brand only, has followed. Finally the Knoll company agreed to pay $135 000 000.

Generic Synthroid (Thyroxine) is one of the best medicines for treatment of low thyroid gland activity. This drug is also often used against certain types of thyroid gland cancer.

You can use it in two ways: before eating or after it and in general without food. The pills have to be taken regularly in the correct time to ensure maximal effect. The remedy is to be swallowed, but if you can’t swallow it, you can try to crush the pill and mix the powder with one or two spoons of water.

Warn your MD about other medicinal products you take and about any serious disabilities if you have any. If you need to take some drugs like insulin or on any other remedy for treatment of some kinds of diabetes, then consult your MD to use Synthroid (levothyroxine 25 mcg) correctly.

It is the most often used name of Levothyroxine Sodium. It’s a synthetic hormone acting on thyroid gland with the same effect as the endogenous one. Thyroid gland hormones are mainly responsible for metabolic rate and fulfill very important functions in an organism. Hormonal medicines improve biotransformation considerably and make transformation of all types of carbohydrates, some kinds of proteins and different fats faster as the organism burns much more calories daily. These kinds of hormones are applied for treatment of a thyroidea disorders and obesity (caused by such type of dysfunction).

A healthy person has enough both hormones of thyroidea of T-3 and T-4 in the organism. If to compare them, then T-3 hormone is 4 times stronger, than T-4 (generally T-4 hormone works after conversion into T-3).

So, now let’s look at some of this remedy’s properties in detail.Synthroid (Levothyroxine) is a drug treating the pineal organ. It replaces the normal hormone usually released by the thyroidea to condition energy and metabolic exchange processes in an organism. This medicine is indicated if the pineal organ doesn't release normal quantity of this important hormone independently.

Synthroid (Levothyroxine 50 mcg) combats mainly hypothyroidism (low quantity of specific thyroidea hormone).

It is frequently indicated for treatment or prevention of different kinds of goiter (enlarged pineal organ) that can become the reason of a hormonal imbalance, radiation therapy or specific types of cancer.


Some drugs can make these pills uneffective if they are taken simultaneously. If you constantly use the remedies listed below:

  • Limeolith;
  • Holestiramin, colestipol;
  • Sucralfate;
  • Natriypolistirolsulfonat;
  • Antacid.

Avoid the intake of following substances causing lower absorbtion of these pills: soy formula for newborns, products containing high amount of cellulose.


If it’s necessary to take this drug in a dose smaller than 100 mkg, it’s necessary to use special remedies of other producers providing necessary dispensing of the medicine in the organism.

For patients suffering from hypothyroidism the initial dose is 50-100 mkg a day, it can be gradually increased (by 50 mkg each 2-3 weeks), for children the initial dose is 12.5-50 mkg/day; for persons suffering from congenital hypothyroidism, especially for children at the age of 6-12 years: 4-5 mkg/kg/day, children of 13-18 years if puberty isn't finished: 2-3 mkg/kg/day, if puberty is finished: 1.7 mkg/kg/day (for children under 6 years this dosage form is contraindicated). For suppressive test: 200 mkg a day during 14 days or 3 mg 1 time in 7 days before the repeated scintigraphy. Euthyroid goiter and its relapse prevention after its resection: for adults – 100-200 mkg a day, for children – 50-150 mkg a day.

How to take?

Take Synthroid precisely according to instructions of your MD. Read carefully all instructions. Your doctor can sometimes change the dosage. Don't take this drug differently from what is prescribed.

Synthroid has the best effect if you take from a half up to one tablet every day before the breakfast. Absorption increases if the stomach is totally empty. Follow all directions and take the tablets always at the same time.

If your child takes this remedy, inform the pediatrician about any weight changes of your little patient. The dosage depends on weight proportion and any differences can affect the previously prescribed dose.

It can take quite a long time before the organism begins to react. Continue to use this drug even if you feel absolutely healthy.
When using Synthroid repeated medical tests can be required. Inform all medical personnel who deals with you that you treat your thyroidea with these tablets.

  • The remedy is to be stored at normal temperature far from humidity sources.
  • Don't share Synthroid with other patients even if you both have same disease.

Side Effects

Call an ambulance if you detect any symptoms of some idiosyncratical reactions to this medicine:

  • beehives;
  • complicated breath;
  • face edema;
  • fast or too irregular cardiac rhythm;
  • breast pain;
  • inflows, perspiration;
  • extraordinary cold;
  • fatigue, insomnia;
  • amnesia, depression or irritability;
  • muscular aches of different types;
  • skin or hair dryness;
  • hair loss;
  • diarrhea;
  • change of weight.

The cumulative side effects can include following:

  • spasms of legs;
  • hyposthenia;
  • cephalalgia;
  • panic;
  • exanthema;
  • easy acomia.

Ask your MD about all possible adverse effects, which aren’t given in this article.


Symptoms of heavy overdose: the thyrotoxic crisis with collapse and coma (sometimes delayed for a longer perod of time after the intake of these pills).

Other symptoms: thorax pain, diarrhea, heart dysfunctions, fever, tremor, cephalodynia, petulance, spasms, increased sweating, vomiting.
Treatment: prescription of beta adrenergic blocker, intravenous injection of glucocorticosteroids, plasma transfusion.


Levels of the thyroidea hormones can be influenced by many other chemical substances. Some kinds of drugs can enhance or reduce the effect of Synthroid.

Many different chemicals can uncontrollably react with the main conponents of this remedy. Not all kinds of interactions can be mentioned here.

Inform your MD about all drugs which you start or stop taking during the treatment with Synthroid. Give the full panel of the remedies you use to all the medical personnel who makes medical manipulations with you.

Drug and Alcohol

It is necessary to limit alcohol intake.


Bella: I take it for several years. I got a recipe for free medicine. I took a hormone of other brand earlier and everything suited me. But now in our city they don't prescribe medicines of import production free of charge, and give the recipe only for tablets of domestic production.

These tablets have terrible side effects. Even those which aren't specified in the instruction. My stomach hurts and I have constant nausea, problems with liver. And on a background of intake of this medicine I have increased appetite and it’s also almost impossible to constrain weight.

I have no opportunity to buy medicines of import production and it’s necessary to take these pills with adverse effects. I took hormone of a different trademark, but this drug is the worst one with the maximum quantity of adverse effects. If I had a choice, I would never take this remedy. It influences ability to drive vehicles and control machine equipment.

Kim_S: My endocrinologist prescribed me these tablets, I have to take them every day before eating, in a dosage of 50 mg. I couldn't lose weight and didn't understand why, my MD explained to me that at dysfunction of thyroid gland, it’s complicated to lose weight, the metabolism is bad. I have begun to take it and the issue has gone.

Derek: After some time after the intake of the medicine, my mother has got constant headaches, dizziness, with such side effects it wasn't clear if the medicine helps or not. The medicine seemed to help at first but after some time I have begun to read the summary and everything was in order, practically all side effects of tablets have coincided with the symptoms of my mother. We decided to go to the doctor again and ask him to change the drug for similar one of some other producer. The doctor told us that there is an analog of a German holding Merk and at the same structure it has no side effects at most of patients. My mother tried to use this one, but it seemed to be useless at all. At the end I can say: this medicine is no good for treatment.

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Review: 2
    • You’re welcome! I’m glad you found the article helpful. If you have any specific questions or need further information, feel free to ask.

  1. Thinking of buying this one for my mom but I’m wary about those amount of side effects..

    • It’s understandable to be concerned about potential side effects when considering a medication for your mom. Synthroid (levothyroxine) is a commonly prescribed medication for managing hypothyroidism, and while it does have possible side effects, they are generally rare and occur in a small percentage of users. It’s important to note that the benefits of treating hypothyroidism with Synthroid often outweigh the risks of potential side effects.


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