Levothyroxine is a drug to treat hypothyroidism, which is a condition of low thyroid hormone levels. In addition, this drug is also used in the treatment of myxedema coma. This medicine should only be used based on a doctor's prescription.

Lack of thyroid hormone can cause metabolic disorders, resulting in complaints, such as fatigue, constipation, dry skin, or forgetfulness.

Levothyroxine, which is an artificial thyroid hormone, will replace or increase thyroid hormone levels that are lacking. That way, thyroid hormone levels can return to balance, and symptoms or complaints can subside.

Merek dagang levothyroxine: Euthyrox, Levothyroxine Sodium, Tiavell, Thyrax

What Is Levothyroxine

Group Prescription drug
Category Hormon tiroid
Benefit Treating hypothyroidism
Consumed by Mature
Levothyroxine for pregnant and lactating women Category A:   Controlled studies in pregnant women have shown no risk to the fetus, and a small possibility of harm to the fetus. Levothyroxine may be absorbed into breast milk. If you are breastfeeding, do not use this medicine without consulting your doctor first.
Drug form Tablets, injections

 Precautions Before Using Levothyroxine

There are several things that you should pay attention to before using levothyroxine, including:

  • Tell your doctor about any history of allergies you have. Levothyroxine should not be given to patients who are allergic to this drug.
  • Tell your doctor if you have adrenal gland insufficiency, thyrotoxicosis , thyroid nodules, heart disease , heart attack, diabetes , porphyria, osteoporosis , blood clotting disorders, kidney disease , obesity, liver disease , or swallowing disorders.
  • Tell your doctor if you have had or have recently had radiotherapy
  • Tell your doctor if you are pregnant, breastfeeding or planning a pregnancy.
  • Tell your doctor if you are taking certain medications, supplements or herbal products.
  • Immediately see a doctor if you experience a drug allergic reaction, overdose, or serious side effects after using levothyroxine.

Dosage and Rules for Using Levothyroxine

Levothyroxine is available in injectable and tablet forms. The following is the dosage of levothyroxine based on the age of the patient, the form of the drug, and the condition being treated:

Form : Tablets

Condition: Hypothyroidism

  • Adult: Initial dose, 50–100 mcg/day. The dose may be increased by 25-50 mcg after 3-4 weeks according to the patient's response and condition until the amount of thyroid hormone is normal. Maintenance dose 100–200 mcg per day.
  • Newborns: Initial dose of 10–15 mcg/kg per day. Dosage may be adjusted every 4–6 weeks.
  • Newborns with thyroid hormone levels <5 mcg/dl: Initial dose of 50 mcg/kg per day.
  • Infants aged 0–3 months: 10–15 mcg/kg per day.
  • Infants aged 3–6 months: 8–10 mcg/kg per day.
  • Infants aged 6–12 months: 6–8 mcg/kg per day.
  • Children 1–5 years: 5–6 mcg/kg per day.
  • Children 6–12 years: 4–5 mcg/kg per day.
  • Children > 12 years: 2–3 mcg/kg per day.
  • Adolescents who have entered puberty: Dosage follows the adult dosage.

Condition: TSH ( thyroid stimulating hormone ) suppressor

  • Adult: 2 mcg/kg per day, once daily as a single dose to suppress TSH in thyroid cancer or goiter.

Form : Intravenous injection (IV)

Condition: Myxedema coma

  • Adult: Initially 200–500 mcg. On the following day the drug can be given as much as 100-300 mcg if needed. Dosage can be reduced according to the patient's response and condition.
  • Elderly: The doctor will adjust the dosage according to the patient's condition.

How to Use Levothyroxine Properly

Always follow the doctor 's advice and read the instructions on the drug packaging before using levothyroxine tablets. Levothyroxine injectable form will be given by a doctor or medical personnel under the supervision of a doctor according to the patient's condition and response.

Take levothyroxine tablets on an empty stomach, for example 30–60 minutes before breakfast. Swallow the tablet whole with the help of a full glass of water. Take the drug at the same time every day.

If you forget to take levothyroxine tablets, consume them immediately if the distance to the next consumption schedule is not too close. If it's close, ignore it and don't double the dose.

Tell your doctor if you frequently forget to take levothyroxine. Take levothyroxine regularly for maximum treatment results. Do not stop using the drug without consulting your doctor first.

During treatment with levothyroxine, you need to check your thyroid hormone levels regularly. Follow the control schedule given by the doctor.

Store levothyroxine in a dry place, at room temperature, and away from direct sunlight. Keep this drug out of reach of children.

Levothyroxine Interactions with Other Drugs

The use of levothyroxine with other drugs can cause several drug interaction effects, such as:

  • Decreased absorption of levothyroxine when used with iron , antacids, bile acids, cholestyramine , simeticone, calcium carbonate, calcium acetate , or sucralfate
  • Decreased levels of the hormone tri-iodothyronine (T3) in the blood when used with amiodarone or propranolol
  • Decreased blood levels of levothyroxine when used with carbamazepine , phenytoin , phenobarbital , rifampicin , lithium , estrogens , androgenic hormones , or sertraline
  • Influence on the effectiveness of antidiabetic drugs
  • Increased risk of developing hypertension or tachycardia when used with ketamine
  • Increased risk of side effects, such as high blood pressure , palpitations, or chest pain when used with epinephrine
  • Increased risk of confusion, sleep disturbances, irritability when used with piracetam
  • Increased risk of bleeding when used with  warfarin  

Levothyroxine Side Effects and Dangers

The following are some of the side effects that can occur after using levothyroxine:

  • Lost weight
  • Headache
  • Leg cramps or joint pain
  • Vomiting
  • Fever
  • Diarrhea
  • Changes in the menstrual cycle
  • Hair loss
  • Appetite increases
  • Tremor 

Check with your doctor if these side effects don't go away or get worse. Immediately see a doctor if you experience an allergic drug reaction or more serious side effects, such as:

  • Weakness, fatigue, or insomnia
  • Restlessness or  mood swings
  • Headaches, leg cramps, or muscle aches, which are getting worse
  • Persistent diarrhea or drastic weight loss
  • Chest pain , fast, irregular heartbeat, or heart palpitations
  • Fever , hot flashes , or excessive sweating
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