Levothyroxine is a synthetic thyroid hormone used to treat hypothyroidism, a condition in which the thyroid gland does not produce enough thyroid hormone.
The drug is available under the trademarks of Levothroid, Levoxyl, Levo-T, Synthroid, Tirosint and Unithroid.
Thyroid hormones affect the metabolism of protein, fats and carbohydrates. They also affect the growth and development of man.
If left untreated, hypothyroidism can lead to poor growth, slow speech, loss of energy, weight gain, hair loss, dry skin and increased sensitivity to cold temperatures.
Levothyroxine can help reverse these symptoms. The drug can also help treat the congenital form of hypothyroidism, as well as an enlarged thyroid (goiter) and thyroid cancer.
Levothyroxine has been available in the United States since the 1950s, but the Food and Drug Administration (FDA) did not approve it in 2000.
The thyroid hormone is not a tool for treating obesity, and people with normal thyroid function should not take levothyroxine.
If you have a healthy thyroid and you will take levothyroxine, you can develop life-threatening side effects. This is especially true if you are taking a drug with amphetamines.
Although levothyroxine treats the inactive thyroid, this is not a cure for this condition. You should also understand that it may take several weeks before you see an improvement in symptoms.
Women with long-term levothyroxine therapy may be at greater risk of osteoporosis. Over time, the drug may lead to a decrease in bone mineral density.
In a study published in 2014, the relationship between the risk of bone damage and levothyroxine among elderly women with low thyroid levels was studied.
The researchers concluded that physicians should be particularly concerned about the excessive use of levothyroxine in elderly women with osteoporosis.
Before taking levothyroxine, tell your doctor if you have ever had:
- Heart diseases, such as atherosclerosis (“hardening of the arteries”)
- High blood pressure
- Pain in the chest (angina pectoris)
- Heart Attack
- Kidney disease
- Insufficient adrenal or pituitary gland
- Blood clotting disorders
Tell your doctor if you are planning any operations.
People with heart disease or elderly people with an increased risk of heart disease may need a lower dose of levothyroxine.
Levothyroxine and pregnancy
Tell your doctor if you are pregnant, you may become pregnant or breast-feed before taking levothyroxine.
Studies show that it is safe to take levothyroxine during pregnancy, although your doctor will probably adjust the dose of levothyroxine during pregnancy.
If you find that you have hypothyroidism during pregnancy, your doctor will probably be treating this condition.
In addition, women with low thyroid activity may need to take levothyroxine to provide enough breast milk. Because of this, doctors can vary the dosage for women who are breast-feeding
Usually it is considered safe for children to tolerate thyroxine.
Levothyroxine: side effects
Levothyroxine may cause side effects. Some of them include:
- Weight loss
- Stomach cramps
- Excessive sweating
- Increased appetite
- Changes in the menstrual cycle
- Sensitivity to heat
- Temporary hair loss, especially among children during the first month of treatment
There may be more serious side effects. If you have any of these side effects, stop taking levothyroxine and seek medical help immediately:
- Thoracic pain
- Rapid or irregular heartbeat or pulse
It is very important that your doctor knows about all the medicines that you take, including illegal drugs and any over-the-counter herbs or supplements.
Types of drugs that interact with levothyroxine include:
- Blood solvents such as warfarin (coumadin)
- Antidepressants or medications used to treat anxiety
- Cardiac drugs such as metoprolol (Lopressor, Toprol), propranolol (Inderal) and digoxin (lanoxin)
- Drugs such as phenytoin (Dilantin)
- Estrogens and oral contraceptives
- Diabetic drugs, including insulin
You should take levothyroxine on an empty stomach 30-60 minutes before breakfast.
Talk with your doctor about how certain foods can affect the absorption of the drug and the dosage of the medication.
Levothyroxine is released as a tablet, which you take through the mouth. Take it with a full glass of water.
When prescribing levothyroxine to a child, you can crush a tablet and mix it in 1 to 2 teaspoons of water. Do not mix the product with food. Use this mixture immediately.
Your dosage of levothyroxine depends on many variables, including:
- Your age
- The weight
- The severity of your condition
- Other health problems
- Other medications that you take
When prescribing levothyroxine, your doctor will need to find the right balance.
If your dose is too high, the thyroid level will be too high, which can lead to heart problems and bone loss.
Your doctor will probably start with a low dose of levothyroxine and gradually increase it until the thyroid level is in the normal range.
As soon as your doctor finds the appropriate dose of medicine for you, you will not need to consult a doctor so often.
Overdose with levothyroxine
You should not take more levothyroxine than your doctor prescribes.
If you take too many medicines, you may develop symptoms of overactive thyroid gland, including fatigue, heat sensitivity, increased appetite and sweating.
Symptoms of an overdose with levothyroxine may also include:
- Confusion and disorientation
If you or someone has symptoms of an overdose, call the Toxicology Center by phone. If someone has fallen or does not breathe, call 03.
The missed dose of levothyroxine
It is important not to skip doses of levothyroxine. If you accidentally miss a dose, take it as soon as you remember.
If it’s time for the next regular dose, skip it.
Do not take twice as much levothyroxine at a time to make up the missed dose.