Package leaflet: Information for the user

Introduction

Package leaflet: information for the user

Levotiroxina Sanofi 100 micrograms tablets

Levothyroxine sodium

Read all of this leaflet carefully before you start taking this medicine because it contains important information for you.

Keep this leaflet as you may need to read it again.
If you have any questions, ask your doctor or pharmacist.
This medicine has been prescribed for you only, and you should not give it to other people even if they have the same symptoms as you, because it may harm them.
If you experience any adverse effects, consult your doctor or pharmacist, even if they are adverse effects not listed in this leaflet. See section 4.

Leaflet contents

What Levotiroxina Sanofi 100 micrograms is and what it is used for
What you need to know before taking Levotiroxina Sanofi 100 micrograms
How to take Levotiroxina Sanofi 100 micrograms
Possible side effects
How to store Levotiroxina Sanofi 100 micrograms
Contents of the pack and other information

1. What Levotiroxina Sanofi 100 micrograms is and what it is used for

Levotiroxina Sanofi 100 micrograms is a medicine containing levotiroxina, a thyroid hormone, as the active substance. It has the same effect as the hormone naturally produced by the body.

Levotiroxina Sanofi is used to replace the missing thyroid hormone and/or to relieve impaired function of your thyroid gland.

Levotiroxina Sanofi is used:

to replace hormone deficiency in all forms of hypothyroidism (underactive thyroid),
to prevent recurrence of goitre (thyroid enlargement) after surgical removal of goitre in patients with normal thyroid function (depending on thyroid function after surgery),
to treat benign goitre (benign thyroid tissue) in patients with normal thyroid function,
as supplementary therapy in hyperthyroidism (overactive thyroid) in patients receiving thyrastatic agents (antithyroid medication), after achieving a normal metabolic status,
in malignant thyroid tumours, especially after surgery to suppress the growth of new tumour tissue and as a hormone replacement in the absence of thyroid hormone,
to investigate thyroid function (thyroid suppression test).

2. What you need to know before taking Levotiroxina Sanofi 100 micrograms

Do not take Levotiroxina Sanofi

if you are hypersensitive (allergic) to sodium levothyroxine or any of the other components of this medicine (listed in section 6),
if you have any of the following disorders or conditions listed below:
- untreated hyperactive thyroid,
- untreated adrenal insufficiency (poor adrenal function),
- untreated pituitary gland dysfunction, if it has resulted in adrenal insufficiency (poor adrenal function) requiring treatment,
- acute myocardial infarction,
- acute inflammation of the heart muscle (myocarditis),
- acute inflammation of all layers of the heart (pancarditis).

If you are pregnant, you must not take Levotiroxina Sanofi at the same time as another medicine for hyperactive thyroid (called antithyroid agents) (see section “Pregnancy, breastfeeding and fertility”).

Medical condition reviews

Before starting treatment with Levotiroxina Sanofi, the following disorders or conditions must be ruled out or treated:

coronary heart disease,
chest pain with a feeling of tightness (angina pectoris),
high blood pressure,
poor pituitary gland function and/or poor adrenal function,
areas in the thyroid gland producing uncontrolled amounts of thyroid hormone (thyroid autonomy).

These disorders or conditions must also be ruled out or treated before performing the so-called thyroid suppression test to investigate thyroid function. However, this does not apply to thyroid autonomy, as the test is sometimes used to detect this condition.

Warnings and precautions

Talk to your doctor or pharmacist before starting to take Levotiroxina Sanofi.

Take special care with Levotiroxina Sanofi

if you have previously had a heart attack, or if you have coronary heart disease, heart failure, heart rhythm disorders (tachycardias), or chronic cardiomyopathy (non-acute inflammation of the heart muscle), or if you have had hypothyroidism for a long period. In these cases, excessively high levels of hormone in the blood should be avoided. Your thyroid hormone levels should therefore be monitored more frequently. Consult your doctor if mild signs of hyperthyroidism appear as a result of taking Levotiroxina Sanofi (see section 4. “Possible side effects”).
if you have hypothyroidism due to a pituitary gland disorder. In this case, you may also have poor adrenal cortex function, which must first be treated by your doctor (treatment with hydrocortisone). Without appropriate treatment, this could trigger an acute adrenal crisis.
if thyroid autonomy is suspected (areas in the thyroid gland producing uncontrolled amounts of thyroid hormone). Before starting treatment, this should be investigated with further thyroid function tests.
if you are a postmenopausal woman at high risk of bone fragility (osteoporosis), your doctor should monitor your thyroid function more frequently. This is to avoid increased blood levels of thyroid hormone and to ensure the lowest required dose is administered.
if you have diabetes. See information in the section “Other medicines and Levotiroxina Sanofi”.
if you are being treated with certain anticoagulants (blood-thinning medicines, such as dicoumarol) or medicines that may affect thyroid function (e.g. amiodarone, tyrosine kinase inhibitors [for cancer treatment], salicylates, and high-dose furosemide). See information in the section “Other medicines and Levotiroxina Sanofi”.
if treating a premature newborn with low birth weight. Extreme caution must be taken when initiating levothyroxine treatment, as circulatory collapse may occur due to immature adrenal function (see section 4. “Possible side effects”). Blood pressure should be monitored periodically when starting levothyroxine in very low birth weight premature infants, as a rapid drop in blood pressure (known as circulatory collapse) may occur.
if you have a history of epilepsy, as the risk of seizures increases when levothyroxine is administered.
if you experience an allergic reaction (see section “Possible side effects”). Contact your doctor or healthcare professional immediately or go to the nearest hospital emergency room without delay.
if you are undergoing laboratory tests to monitor your thyroid hormone levels, you must inform your doctor or laboratory staff if you are taking or have recently taken biotin (also known as vitamin H, vitamin B7, or vitamin B8). Biotin can affect laboratory test results. Depending on the test, results may be falsely elevated or falsely reduced due to biotin. Your doctor may instruct you to stop taking biotin before blood tests. You should also be aware that other products you may be taking, such as multivitamin preparations or supplements for hair, skin, and nails, may also contain biotin. This could affect laboratory test results. Inform your doctor or laboratory staff if you are taking these products (see information in the section “Other medicines and Levotiroxina Sanofi”).

Inappropriate use (off-label use)

Do not take Levotiroxina Sanofi for weight loss. If thyroid hormone levels in the blood are within the normal range, additional intake of thyroid hormones will not cause weight loss. Serious or even life-threatening adverse effects may occur if you take additional thyroid hormones or increase your dose without your doctor’s specific advice, especially when combined with certain weight-loss products.

Changing treatment

Thyroid imbalance may occur if you need to switch from your current medication to another product containing levothyroxine. Consult your doctor if you have any doubts about changing your medication. Close monitoring (clinical and laboratory parameters) is required during the transition period. Inform your doctor if you experience any adverse effects, as this may indicate that your dose needs to be adjusted up or down.

Elderly patients

In elderly patients, more careful dose adjustment (especially if they have heart problems) is required, and more frequent medical check-ups should be performed.

Other medicines and Levotiroxina Sanofi

Inform your doctor or pharmacist if you are taking, have recently taken, or might need to take any other medicines.

Levotiroxina Sanofi influences the effects of the following agents and medicine groups:

Antidiabetic medicines (medicines that lower blood sugar levels) (such as metformin, glimepiride, glibenclamide, and insulin):

If you have diabetes, you should monitor your blood sugar levels regularly, especially when starting and stopping thyroid hormone treatment.

Your doctor may need to adjust your antidiabetic medication dose, as levothyroxine may reduce the effect of blood sugar-lowering medicines.

Anticoagulant medicines that prevent blood clotting – known as anticoagulants (coumarin derivatives):

When taking Levotiroxina Sanofi together with coumarin derivatives (e.g. dicoumarol), you should have your blood coagulation checked regularly. Your doctor may need to reduce your anticoagulant dose, as levothyroxine may enhance its effect.

The effect of Levotiroxina Sanofi is influenced by other medicines, as follows:

Ion-exchange resins:

After taking Levotiroxina Sanofi, wait 4–5 hours before taking agents used to lower blood fat levels (e.g. cholestyramine, colestipol) or to remove high concentrations of potassium or phosphate from the blood (calcium salts and sodium polystyrene sulfonate, sevelamer). Otherwise, these medicines will block the absorption of levothyroxine in the intestine and make it less effective.

Bile acid sequestrants:

Colesevelam (a medicine used to lower high cholesterol levels in the blood) binds to levothyroxine and thereby reduces its intestinal absorption. Therefore, Levotiroxina Sanofi should be taken at least 4 hours before colesevelam.

Medicines containing aluminium used to bind stomach acid, medicines containing iron, calcium carbonate, proton pump inhibitors:
Take Levotiroxina Sanofi at least 2 hours before taking medicines containing aluminium (used to bind stomach acids [antacids, sucralfate]), medicines containing iron, or calcium carbonate. Otherwise, these medicines may reduce the intestinal absorption of levothyroxine and make it less effective.
Proton pump inhibitors (such as omeprazole, esomeprazole, pantoprazole, rabeprazole, and lansoprazole) are used to reduce stomach acid production, which may reduce intestinal absorption of levothyroxine and thus make it less effective. If you are taking levothyroxine at the same time as a proton pump inhibitor, your doctor should monitor your thyroid function and may need to adjust the dose of Levotiroxina Sanofi.
Propylthiouracil, glucocorticoids, beta-blockers (especially propranolol):

Propylthiouracil (used for hyperactive thyroid), glucocorticoids (adrenocortical hormones, “cortisone”), and beta-blockers (used to reduce heart rate and blood pressure) block the conversion of levothyroxine to triiodothyronine (liothyronine), the more active form, and may therefore reduce the effectiveness of Levotiroxina Sanofi.

Amiodarone, iodine-containing contrast media:

Amiodarone (used in the treatment of heart rhythm disorders) and iodine-containing contrast media (some agents used in X-ray diagnostics) may – due to their high iodine content – trigger either hyperactive or hypoactive thyroid function. Special caution is required in cases of nodular goitre, where undetected areas in the thyroid gland may produce uncontrolled amounts of thyroid hormone (autonomies). Amiodarone blocks the conversion of levothyroxine to triiodothyronine (liothyronine), the more active form, and may therefore affect the effect of Levotiroxina Sanofi. Your doctor may adjust the dose of Levotiroxina Sanofi.

Tyrosine kinase inhibitors (for cancer treatment):

If you are taking levothyroxine together with tyrosine kinase inhibitors (e.g. imatinib, sunitinib, sorafenib, or motesanib), your doctor should carefully monitor your symptoms and thyroid function. There may be some loss of levothyroxine effect. Your doctor may adjust the dose of Levotiroxina Sanofi.

The following medicines may influence the effect of Levotiroxina Sanofi:
- salicylates, especially at doses above 2.0 g/day (medicines that reduce fever and relieve pain),
- dicoumarol (an anticoagulant agent),
- high doses of furosemide (250 mg) (used to increase urine elimination),
- clofibrate (used to reduce high blood fat levels).
Hormonal contraceptives or hormone replacement therapy medicines:

If you are taking hormonal contraceptives containing oestrogens (“the pill”) or receiving hormone replacement therapy after menopause, your need for levothyroxine may increase.

Sertraline; chloroquine/proguanil:

Sertraline (an antidepressant) and chloroquine/proguanil (used for malaria and rheumatic disease) reduce the effectiveness of levothyroxine.

Rifampicin, carbamazepine, phenytoin, barbiturates, products containing St. John’s wort:

Rifampicin (an antibiotic), carbamazepine (used to treat seizures), phenytoin (used to treat seizures and heart rhythm disorders), barbiturates (used in seizures, anaesthesia; certain sleeping pills), and products containing St. John’s wort (a herbal medicine) may weaken the effect of levothyroxine.

Protease inhibitors (used to treat HIV infection):

If you are taking levothyroxine together with protease inhibitors (lopinavir, ritonavir), your doctor should carefully assess your symptoms and monitor your thyroid function. There may be some loss of levothyroxine effect when administered together with lopinavir/ritonavir.

If you are taking levothyroxine together with semaglutide (an antidiabetic medicine), this may affect levothyroxine levels, and your doctor may need to monitor your thyroid levels and adjust the dose of Levotiroxina Sanofi.
If you are taking or have recently taken biotin, inform your doctor or laboratory staff when laboratory tests are performed to monitor thyroid hormone levels. Biotin can affect laboratory test results (see “Warnings and precautions”).
Orlistat – used to treat obesity.

Levotiroxina Sanofi with food and drinks

If your diet includes soy, your doctor will monitor your thyroid hormone blood levels more frequently. Your doctor may need to adjust the dose of Levotiroxina Sanofi during and after stopping this diet (unusually high doses may be required), as soy-containing products may affect the intestinal absorption of levothyroxine and thus make it less effective.

Do not take Levotiroxina Sanofi with coffee, as it may reduce intestinal absorption of levothyroxine and thus make it less effective. After taking Levotiroxina Sanofi, wait at least 30 minutes to one hour before drinking coffee. Patients who habitually consume coffee and are on levothyroxine therapy are advised not to change their “coffee-drinking habit” without medical supervision and monitoring of levothyroxine levels.

Pregnancy, breastfeeding and fertility

If you are pregnant or breastfeeding, think you may be pregnant, or plan to become pregnant, consult your doctor or pharmacist before taking this medicine.

Proper treatment with thyroid hormones is particularly important during pregnancy and breastfeeding to ensure optimal health of both mother and fetus. Therefore, treatment should continue regularly and under your doctor’s supervision. Despite its extensive use during pregnancy, no adverse effects on pregnancy or on the health of the fetus or newborn have been reported due to levothyroxine.

Thyroid function should be checked during and after pregnancy. Your doctor may need to adjust your dose, as your need for thyroid hormone may increase due to elevated blood levels of oestrogen (female sex hormone) during pregnancy.

During pregnancy, do not take Levotiroxina Sanofi at the same time as antithyroid medicines (also called antithyroid agents), as this would require higher doses of the antithyroid agent. Antithyroid agents (unlike levothyroxine) can cross the placenta into the baby’s bloodstream and may cause hypothyroidism in the fetus. If you have hyperactive thyroid, your doctor should treat you during pregnancy using only low doses of antithyroid agents.

If you are breastfeeding, continue taking levothyroxine as recommended by your doctor.

Even at high treatment doses, the amount of levothyroxine passing into breast milk during breastfeeding is very low and therefore harmless.

Your doctor will not perform suppression tests during pregnancy and breastfeeding.

Hypothyroidism or hyperthyroidism is likely to affect fertility. When treating patients with hypothyroidism, the dose of Levotiroxina Sanofi should be adjusted based on laboratory test results, as an insufficient dose may fail to correct hypothyroidism, while an overdose may cause hyperthyroidism.

Driving and using machines

No studies have been conducted to investigate the effects of Levotiroxina Sanofi on the ability to drive vehicles or operate machinery.

Levotiroxina Sanofi contains sodium

This medicine contains less than 23 mg of sodium (1 mmol) per tablet; hence, it is essentially “sodium-free”.

3. How to take Levothyroxine Sanofi 100 micrograms

Follow exactly the instructions for use of this medicine as given by your doctor. If in doubt, consult your doctor again.

Your doctor will determine the daily dose you need, based on monitoring of your laboratory tests.

Dosage

Tablets with different strengths of the active substance are available (25, 50, 75, 100, 125, 150, 175 and 200 micrograms of levothyroxine sodium), allowing for individualized treatment. This means that in most cases you will only need to take one tablet per day.

At the beginning of treatment, when increasing the dose in adults, or when treating children, your doctor may prescribe tablets with a lower amount of active substance.

Depending on symptoms, your doctor will follow the recommendations below:

For the treatment of hypothyroidism, adults should start with a daily dose of 25–50 micrograms of levothyroxine sodium. This dose may be increased by 25–50 micrograms of levothyroxine sodium, at intervals of 2 to 4 weeks, as directed by your doctor, up to a daily dose of 100–200 micrograms of levothyroxine sodium (equivalent to 1–2 tablets of Levothyroxine Sanofi 100 micrograms).
To prevent recurrence of goiter after goiter removal and for the treatment of benign goiter, a daily dose of 75–200 micrograms of levothyroxine sodium should be taken (up to 2 tablets of Levothyroxine Sanofi 100 micrograms).
As supplementary treatment in the management of hyperthyroidism with thyrostatic agents, a daily dose of 50–100 micrograms of levothyroxine sodium should be taken (equivalent to half to one tablet of Levothyroxine Sanofi 100 micrograms).
After surgery for malignant thyroid tumors, the daily dose is 150–300 micrograms of levothyroxine sodium (equivalent to 1.5–3 tablets of Levothyroxine Sanofi 100 micrograms).
For thyroid function testing using thyroid suppression testing, 200 micrograms of levothyroxine sodium should be taken daily (equivalent to 2 tablets of Levothyroxine Sanofi 100 micrograms) for 14 days until the imaging test (scintigraphy) is performed.

In some cases, a lower dose of thyroid hormone may be sufficient.

Method of administration

The total daily dose should be taken in the morning on an empty stomach, at least 30 minutes before breakfast. The tablets should be swallowed whole (without chewing) with plenty of liquid, preferably a glass of water.

The active substance is better absorbed on an empty stomach than before or after a meal.

Children should receive the total daily dose at least 30 minutes before their first meal of the day. The tablet may also be dissolved in a small amount of water (10–15 ml), and the resulting fine dispersion (which should be freshly prepared for each dose) should be administered with a little additional liquid (5–10 ml).

Use in children

For long-term treatment of congenital hypothyroidism and hereditary hypothyroidism (underactive thyroid), the daily dose is generally 100 to 150 micrograms of levothyroxine sodium per m² of body surface area.

In neonates and infants with congenital hypothyroidism (underactive thyroid), rapid hormone replacement is especially important to achieve normal mental and physical development.

For this type of hypothyroidism, the recommended daily dose is 10–15 micrograms of levothyroxine sodium per kg of body weight during the first 3 months of treatment. Thereafter, your doctor will adjust the required dose individually based on follow-up monitoring (including blood levels of thyroid hormone).

In children with acquired hypothyroidism (underactive thyroid), the recommended starting dose of levothyroxine sodium is 12.5–50 micrograms per day. Your doctor will gradually increase the dose every 2 to 4 weeks until the required dose for long-term treatment is reached. During this time, your doctor should monitor particularly the blood levels of thyroid hormone.

Elderly patients, patients with coronary heart disease, and patients with hypothyroidism

Special caution is required when starting thyroid hormone therapy in elderly patients, patients with coronary heart disease, and patients with severe or long-standing hypothyroidism (underactive thyroid). A low initial dose should be used, increased slowly at prolonged intervals, with frequent monitoring of thyroid hormone levels.

Patients with low body weight and patients with large goiter

Experience shows that a low dose is sufficient even in patients with low body weight and in patients with a large goiter.

Duration of treatment

In most cases, Levothyroxine Sanofi must be taken for a long period in cases of hypothyroidism, after goiter or thyroidectomy, and to prevent regrowth of goiter after its removal.
When used as supplementary therapy for hyperthyroidism, Levothyroxine Sanofi 100 micrograms should be taken for the same duration as thyrostatic agents (antithyroid drugs).
For the treatment of benign goiter in patients with normal thyroid function, a treatment period of 6 months to 2 years is necessary. If treatment with Levothyroxine Sanofi has not achieved the desired result within a reasonable time, your doctor should consider alternative therapeutic options.

If you take more Levothyroxine Sanofi than you should

Signs of overdose are described in section 4, “Possible side effects.” Contact your doctor immediately if these symptoms occur.

In case of overdose or accidental ingestion, contact the Toxicology Information Service at telephone 91 562 04 20, stating the name of the medicine and the amount ingested.

If you forget to take Levothyroxine Sanofi

If you have taken too small a dose or have missed a dose, do not take a double dose to make up for the missed dose. Continue taking your tablets as prescribed in your regular treatment schedule.

If you stop taking Levothyroxine Sanofi

For your treatment to be effective, you must take Levothyroxine Sanofi regularly at the dose prescribed by your doctor. You should never change, stop, or interrupt treatment with Levothyroxine Sanofi on your own, as symptoms may reappear.

If you have any further questions about the use of this medicine, ask your doctor or pharmacist.

4. Possible adverse effects

Like all medicines, this medicine can cause adverse effects, although not everyone experiences them.

Hypersensitivity to the active substance or other components of Levotiroxina Sanofi

If you are hypersensitive to levothyroxine or any of the other components of Levotiroxina Sanofi, allergic reactions affecting the skin and respiratory tract (either immediately or after several days of taking the medicine) may occur, which could be life-threatening. Symptoms may include rash, itching, difficulty breathing, shortness of breath, swelling of the face, lips, throat, or tongue. Contact your doctor or healthcare professional immediately or go to the nearest hospital emergency room without delay.

Intolerance to dosage, overdose

If the prescribed dosage is not tolerated in individual cases, or in the case of an overdose, symptoms typical of an overactive thyroid (hyperthyroidism) may appear, especially if the dose is increased too rapidly at the beginning of treatment.

Very common adverse effects (may affect more than 1 in 10 patients)

Palpitations
Insomnia
Headache

Common adverse effects (may affect up to 1 in 10 patients)

Fast heartbeat (tachycardia)
Nervousness

Rare adverse effects (may affect up to 1 in 1,000 patients)

Increased pressure in the brain (especially in children)

Other adverse effects with unknown frequency (cannot be estimated from available data)

Hypersensitivity
Heart rhythm disorders
Chest tightness or pain (symptoms of angina pectoris)
Skin allergic reactions (e.g. angioedema [difficulty breathing, or swelling of the face, lips, throat, or tongue], rash, urticaria)
Inner restlessness
Muscle weakness and muscle cramps
Bone fragility (osteoporosis) with high doses of levothyroxine, especially in postmenopausal women, mainly when treated for a long period
Feeling of warmth
Menstrual disorders
Diarrhea
Vomiting
Nausea
Weight loss
Tremor
Excessive sweating
Fever
Circulatory collapse in premature newborns with low birth weight (see section 2. “Warnings and precautions”).

Inform your doctor if any adverse effects occur. Your doctor will decide whether the daily dose should be reduced or whether treatment should be interrupted for a few days. As soon as the adverse effect disappears, treatment may be restarted cautiously with a lower dose.

Reporting of adverse effects

If you experience any type of adverse effect, consult your doctor or pharmacist, even if they are possible adverse effects not listed in this leaflet. You may also report them directly via the Spanish Pharmacovigilance System for Human Medicines: https://www.notificaram.es. By reporting adverse effects, you can help provide more information on the safety of this medicine.

5. Storage of Levothyroxine Sanofi 100 micrograms

Keep this medicine out of the sight and reach of children.

Do not use this medicine after the expiry date stated on the packaging after EXP. The expiry date is the last day of the month indicated.

Do not store above 25°C.

Medicines should not be disposed of via wastewater or household waste. Dispose of empty containers and unused medicines at the SIGRE collection point at your pharmacy. If you are in doubt, please ask your pharmacist how to dispose of containers and medicines you no longer need. This will help protect the environment.

6. Contents of the container and other information

Composition of Levotiroxina Sanofi 100 micrograms tablets

The active substance is levothyroxine sodium. Each tablet contains 100 micrograms of levothyroxine sodium.
The other components are: maize starch, pregelatinized starch (from maize), microcrystalline cellulose, sodium carbonate, sodium thiosulfate (F.E.), anhydrous colloidal silica, and hydrogenated castor oil.

Appearance of the product and contents of the container

Levotiroxina Sanofi 100 micrograms are round, white tablets, scored on one side and marked with the code “4L” on both sides.

The tablets may be divided into two equal parts.

Levotiroxina Sanofi 100 micrograms is available in packs of 28 (calendar pack), 50, 84 (calendar pack), 98 (calendar pack), 100 and 500 tablets (10 x 50 tablets).

Only some pack sizes may be marketed.

Marketing Authorization Holder

sanofi-aventis, S.A.

C/ Rosselló i Porcel, 21

08016 Barcelona

Spain

Manufacturer

sanofi-aventis, S.A.

C/ Rosselló i Porcel, 21

08016 Barcelona

Spain

Sanofi-Aventis Deutschland GmbH

Industriepark Hoechst-Brüningstrasse 50

65926 Frankfurt am Main

Germany

This medicinal product is authorized in the Member States of the European Economic Area under the following names:

Germany: L-Thyroxin Winthrop 100 µg Tabletten

Spain: Levotiroxina Sanofi 100 microgramos comprimidos

France: L-Thyroxin Henning 100 microgrammes comprimé sécable

Date of the most recent review of this leaflet: November 2025

Detailed information on this medicinal product is available on the website of the Spanish Agency of Medicines and Health Products (AEMPS) https://www.aemps.gob.es/

Levotiroxine Sanofi 100 micrograms tablets