Levothyroxine Levothyroxine

Levothyroxine And Its Use


Highlights For Levothyroxine

  1. Levothyroxine oral tablet is accessible in both brand-name and generic versions. 

  2. Levothyroxine is obtainable in three formulations: an oral tablet, an oral capsule, and an injectable solution.

  3. The primary use of the Levothyroxine oral tablet is for addressing hypothyroidism. Additionally, it is employed in treating goitre and specific types of thyroid cancer.

What Is Levothyroxine?

Levothyroxine is a medication that can be taken orally in the form of a tablet or capsule, or it can be given as an injectable solution by a healthcare provider.


Levothyroxine oral tablets can be purchased under the different brand names. It is also a generic option typically cheaper than its brand-name counterpart. It may only be available in some strengths or forms as its brand-name counterpart.


Levothyroxine oral tablet may be prescribed with other medications as part of a comprehensive treatment plan.

Why It’s Used

Levothyroxine is a type of medication used to treat hypothyroidism, which is a condition that occurs when the thyroid gland doesn't produce enough thyroid hormones. It can also treat goitre, an enlargement of the thyroid gland, and certain types of thyroid cancer.

How It Works

Levothyroxine is a type of hormone that is used to treat conditions related to the thyroid. It helps to replace the hormone that the thyroid would typically produce if it were functioning normally. It belongs to a group of medications that work similarly and are used to treat similar conditions.

Levothyroxine Side Effects

The oral tablet form of levothyroxine can cause side effects.

More Common Side Effects

Some of the more common side effects of levothyroxine are:


  • Mood swings

  • Anxiety

  • Excessive sweating

  • Increased appetite

  • Tremors

  • Headache

  • Hyperactivity

  • Tiredness

  • Hair loss (usually temporary)

  • Changes in menstrual periods

  • Vomiting

  • Stomach cramps

  • Heat sensitivity

  • Muscle weakness

  • Trouble sleeping

  • Irritability

  • Weight loss

  • Diarrhoea

  • Nervousness


If the side effects you experience are minor, they should pass within a few days or a couple of weeks. Contacting your doctor or pharmacist is vital if they are more severe or persist.

Serious Side Effects

Seek medical attention immediately if you experience any severe side effects. These can include, but are not limited to, the following symptoms: If your symptoms feel life-threatening or you think you have a medical emergency, connect immediately with your doctor.


An attack of the heart. Some of the symptoms include:

  • Discomfort in your upper body

  • Shortness of breath

  • Chest pain

Failure of the heart. There can be a variety of symptoms.

  • Swift heart rate

  • Shortness of breath

  • Extreme tiredness

  • Unexpected weight gain

  • Swelling in your legs, ankles, or feet

  • Irregular heart rhythm



We aim to give you the most accurate and up-to-date information. However, the effects of drugs may vary from person to person. We can't guarantee that this information contains all potential side effects. Therefore, you must consult your healthcare provider, who is familiar with your medical history, before taking any medications. This information should not be considered a substitute for professional medical advice.

Levothyroxine May Interact With Other Medications.

Medications, vitamins, or herbs taken alongside levothyroxine oral tablets can interact with the drug, changing how it works. This can have harmful effects or reduce the drug's effectiveness.


To minimise potential interactions, your doctor must manage your medications properly. Please make sure to let your doctor know of any medicines, vitamins, or herbs you take. To know the possible effects of combining this drug with something else you are taking, consult your doctor or pharmacist.


The following medications can interact with levothyroxine and should be avoided or taken with caution:

Interactions That Increase The Risk Of Side Effects

Certain drugs, such as antacids, calcium supplements, iron supplements, and cholesterol-lowering medications, may interact with levothyroxine and increase the risk of adverse effects when taken together.


Antidepressants such as amitriptyline and maprotiline. Taking both antidepressants and levothyroxine together can cause increased side effects, which may lead to irregular heart rhythms (arrhythmias).


Sympathomimetic drugs such as pseudoephedrine and albuterol It is essential to take these drugs with caution and under the supervision of a doctor. Regular check-ups and monitoring should be done to ensure that the medicines are working correctly and that your heart is healthy.


Blood thinners such as warfarin If you are using a blood thinner medication, your doctor may need to adjust the dosage if you are also taking levothyroxine. This is because taking these drugs together may increase your risk of bleeding.


Interactions That Can Make Your Drugs Less Effective

When levothyroxine is less effective, Certain medications can reduce the effectiveness of levothyroxine, which is used to treat certain medical conditions. Examples of drugs that may inhibit levothyroxine include:


  • The antidepressant sertraline. Your doctor may need to increase your levothyroxine dosage if you also take sertraline to ensure that it continues to be effective.

  • Rifampin, carbamazepine and phenobarbital, which are anti-seizure drugs, are commonly used.

  • Calcium carbonate or ferrous sulfate. Taking levothyroxine at least 4 hours before or after other medications is vital to ensure its effectiveness.

  • Colesevelam, cholestyramine, colestipol, kayexalate, or sevelamer. To ensure that levothyroxine works appropriately, take it at least 4 hours before these medications.

  • Orlistat

  • Aluminium and magnesium antacids, as well as simethicone.

  • Imatinib, for example, belongs to the tyrosine-kinase inhibitor class of cancer drugs.


When Other Drugs Are Less Effective: The following drugs may not work as effectively when used with levothyroxine, as the amount of these drugs in the body may be reduced:


Insulin, metformin, nateglinide, glipizide, and pioglitazone are all used to treat diabetes.

When taking levothyroxine concurrently with any of these diabetes drugs, it may be necessary for your doctor to adjust your dosage of said medications.


Digoxin. Taking digoxin with levothyroxine can increase the effects of the drug. Therefore, if you are taking both medications, it is essential to consult your doctor to determine the appropriate dosage of digoxin that is safe to take with levothyroxine.


Theophylline. If you are taking theophylline and levothyroxine, your doctor may keep track of the amount of theophylline in your body.


Disclaimer: We strive to give you the most up-to-date and accurate information. However, we cannot guarantee that this information includes all possible drug interactions, as drugs may interact differently in each person. This information should not be relied upon as a substitute for medical advice. Always consult your healthcare provider concerning any interactions between prescription drugs, vitamins, herbs, supplements, and over-the-counter medications you are taking.

How To Take Levothyroxine

The amount of medication, the form of the medication, and the frequency of use will all depend on:

  • Your age,

  • The medical condition under consideration,

  • The extent of severity of your situation,

  • Any other underlying medical conditions you may have,

  • Your response to the initial dose.


Dosage For Hypothyroidism

Adult Dosage (Ages 18–49 Years):

  • The dose of this medication needed for you will depend on your age, body weight, thyroid hormone levels, any other medical conditions you may have, and any other medications you may be taking. The usual dose is 1.6 mcg/kg of body weight per day.

  • Generally, the recommended amount is 200 micrograms per day at maximum.

Child Dosage (Ages 0–17 Years):

The medication to be taken is determined by the patient's weight and the amount of thyroid hormones in their body.

Senior Dosage (Ages 50 Years And Older):

  • The typical starting dosage is 12.5–25 mcg/day.

  • Your doctor will measure your thyroid hormone levels every 6-8 weeks and adjust your dosage accordingly.

Dosage For Goiter

Adult Dosage (Ages 18 Years And Older):

Your doctor will determine the appropriate medication dosage for your needs and thyroid hormone levels and may adjust it depending on your current thyroid hormone level.

Child Dosage (Ages 0–17 Years):

However, adults should talk to their doctor about the proper dosage for their particular situation. The dosage should be adjusted based on the patient's age, weight and health. Patients should always take the entire prescribed dosage of any medication.


Dosage For Thyroid Cancer

Adult Dosage (Ages 18 Years And Older):

For example, if you take thyroid medication, your doctor may adjust the dosage depending on your blood test results.

Child Dosage (Ages 0–17 Years):

People under the age of 18 should not follow any dosage recommendations.

Dosage For Special Populations

For Pregnant Women:  It may be necessary to increase your levothyroxine dosage.

The recommended starting dosage for people with heart disease is 12.5–25 mcg/day.

Your dosage may be adjusted every 6–8 weeks.



Only adjust dosages after talking to a healthcare provider first. This list is not a substitute for professional medical advice, diagnosis, or treatment. Always speak with a healthcare provider for any questions you have about your medication.


Vitamin Supplements And Antacids Warning

To ensure proper absorption of levothyroxine, do not take it within four hours of taking iron and calcium supplements or antacids.

Allergy Warning

A severe allergic reaction can occur when taking levothyroxine. The following symptoms may occur:

  • Vomiting

  • Swelling of your face, lips, throat, or tongue

  • Wheezing

  • Nausea

  • Stomach pain

  • Flushing

  • Fever

  • Trouble breathing

  • Skin rash or hives

  • Diarrhoea


If you experience any of these symptoms, it is recommended that you seek medical attention immediately by connecting to your doctor.


If you have experienced an allergic reaction to this drug in the past, do not retake it.

Consuming it again could lead to fatal consequences.

Food Interactions Warning

Certain foods, including soybean flour, cotton seed meal, walnuts, and other dietary fibres, may affect Levothyroxine absorption.

Warnings For People With Certain Health Conditions

For People With Heart Problems: Levothyroxine can seriously affect your heart, such as heart attack, abnormal heart rhythm, and heart failure. If you already have heart problems or a history of heart problems, your risk of experiencing these side effects is even higher. Therefore, informing your doctor if you have any heart issues before taking levothyroxine is essential. Your doctor may adjust the dosage to reduce your risk.


For People With Diabetes: It is essential to inform your physician if you have diabetes. While taking levothyroxine, your doctor may need to monitor your blood sugar level more closely and change your diabetes medication if necessary, as this drug may affect your diabetes.


For People With Osteoporosis: Prolonged use of levothyroxine may decrease bone mineral density, increasing your risk of bone fractures.


For People With Adrenal Or Pituitary Gland Problems: If you have any issues with your adrenal or pituitary glands, it is essential to inform your doctor before taking levothyroxine. Levothyroxine can alter the levels of thyroid hormones in your body, which could worsen any existing issues.


For People With Blood Clotting Disorders: Let your doctor know if you have any blood clotting disorders. Taking levothyroxine may make it more difficult for your blood to clot and cause bleeding.


Warnings For Other Groups

For Pregnant Women: If you are pregnant or planning to become pregnant, it is recommended that you speak to your doctor about taking levothyroxine. Research has not found evidence suggesting this drug hurts the developing fetus. It is believed that taking this drug during pregnancy will not likely cause harm.


It is essential to continue taking the prescribed medication for hypothyroidism during pregnancy, as untreated hypothyroidism can have severe consequences for you and your baby.


For Breastfeeding Women: While small amounts of levothyroxine can enter breast milk, it is generally safe to take while breastfeeding. It is essential to consult with your doctor to determine the best way to feed your infant while taking levothyroxine.


For Seniors: Due to the potential for adverse heart effects, individuals over 65 may be recommended to start with a lower drug dosage. This reduces the risk of developing adverse heart effects, such as irregular heart rhythms.


For Children: Levothyroxine, a tablet medication, has been deemed safe for children of all ages to treat hypothyroidism.

Take As Directed

If taken incorrectly, Levothyroxine oral tablets can cause serious health risks. Taking this medication as prescribed by a doctor is essential for long-term treatment.


If you stop or don’t take the drug, Low thyroid hormones can cause fatigue, sluggishness, delayed speech, difficulty with bowel movements, and skin thickening. In severe cases, this may cause a person to coma.


If you miss doses or don’t take the drug on schedule, For your medication to be effective, it is crucial to maintain a consistent level in your body. If the level of the drug falls too low, it may not work as well or may not work at all.


If You Take Too Much: If you take too much of this drug, it could lead to a potentially dangerous overdose. Some of the signs and symptoms of an overdose may include:

  • Trouble breathing

  • Stomach pain

  • Swelling of your face, lips, throat, or tongue

  • Nausea

  • Fever

  • Diarrhoea

  • Flushing

  • Vomiting

  • Wheezing

  • Skin rash or hives


If you believe you have taken an excessive dosage of this medication, contact your physician or the nearest poison control centre. If your symptoms are severe, immediately connect with your doctor.


What To Do If You Miss A Dose: If you forgot to take your dose and remember a few hours before your next scheduled dose, only take one. Do not attempt to make up for the missed dose by taking two doses at once, as this could cause dangerous side effects.


How To Tell If The Drug Is Working: As your thyroid hormone levels improve, you should notice an increase in energy, a decrease in feelings of tiredness and weakness, and other positive changes.

Important Considerations For Taking Levothyroxine

If your doctor prescribes levothyroxine, keep the following points in mind.


  • Take levothyroxine without food on an empty stomach.

  • Take levothyroxine in the morning. Take it 30 minutes to 1 hour before your first meal.

  • You can cut or crush the tablet.


  • Maintain levothyroxine at room temperature within the range of 59°F to 86°F (15°C to 30°C).

  • Shield it from exposure to light.

  • Do not store this medication in humid or damp environments like bathrooms.


When you receive a prescription for this medication, it is refillable. Your doctor will indicate the number of refills authorised on the prescription. You do not need to obtain a new refill prescription, as the existing prescription is valid.


Keeping your medication with you while travelling:

  • Ensure you have your medication with you at all times. When travelling by air, never stow it in checked luggage; instead, keep it in your carry-on bag.

  • There is no need for concern regarding airport X-ray machines as they do not pose any risk to your medication.

  • You might be required to present the pharmacy-labeled container to airport personnel, so always carry the original prescription-labeled container.

  • Avoid storing this medication in your car's glove compartment, especially in extremely hot or cold weather conditions.

Clinical Monitoring

During your treatment with this drug, your doctor will monitor your thyroid hormone levels by conducting blood tests. This will determine if the medication is effective and your thyroid hormone level is within the optimum range.

Your Diet

Certain foods, such as soybean flour, cotton seed meal, walnuts, and other dietary fibres, may affect your body's ability to absorb levothyroxine. If you should make any changes to your diet, it is essential to discuss them with your doctor.

Are There Any Alternatives?

Your doctor can suggest alternative medications that are more effective for your condition. Speak with them about the other available drug options and determine which would be best for you.


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